JP2019029671A - Piezoelectric material, piezoelectric element, vibration-wave motor, optical device and electronic device - Google Patents

Abstract

To provide a piezoelectric material which is small in the load on an environment, and which achieves both of a large piezoelectric constant and a large mechanical quality coefficient.SOLUTION: A piezoelectric material comprises a plurality of crystal grains including Ba, Ca, Ti, Zr, Mn and O. The plurality of crystal grains have an average equivalent circle diameter of 1.0 μm or more and 10 μm or less. The plurality of crystal grains include: a crystal grain A having a first domain of 300 nm or more and 800 nm or less in width; a crystal grain B having a second domain of 20 nm or more and 50 nm or less in width.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric material not containing lead, and a piezoelectric element, a vibration wave motor, an optical device, and an electronic device using the piezoelectric material.

  Lead zirconate titanate containing lead is a typical piezoelectric material, and is used in various piezoelectric devices such as actuators, oscillators, sensors and filters. However, if lead components contained in discarded piezoelectric materials dissolve into the soil, it may adversely affect the ecosystem, so the development of lead-free piezoelectric materials has been promoted for lead-free piezoelectric devices. It is actively done.

By the way, in order to manufacture a piezoelectric device having a high vibration speed, a piezoelectric material that has both a large piezoelectric constant (d ₃₁ and d ₃₃ ) and a large mechanical quality factor (hereinafter simply referred to as “Q _m ”) is required. Become.

One promising lead-free piezoelectric material that can replace lead zirconate titanate is a barium calcium zirconate titanate (hereinafter referred to as “BCTZ”) lead-free piezoelectric material. Patent Document 1 discloses a barium titanate-based material as a lead-free piezoelectric material having an excellent piezoelectric constant. The barium titanate-based material _{{[(Ba 1-x1 M1} x1) ((Ti 1-x Zr x) 1-y1 N1 y1) O 3] -δ% [((Ba 1-y Ca y) 1- _{x2 M2 x2) (Ti 1-} y2 N2 y2) O 3]} has the composition. Here, M1, N1, M2, and N2 represent additive elements. In barium titanate-based material, the first end component _{(Ba 1-x1 M1 x1)} ((Ti 1-x Zr x) 1-y1 N1 y1) O 3 has a rhombohedral structure, the second end component _{((Ba 1-y Ca y} ) 1-x2 M2 x2) (Ti 1-y2 N2 y2) O 3 has a tetragonal structure. In the barium titanate-based material of Patent Document 1, two components having different crystal systems are made into a quasi-binary solid solution, and the degree of freedom in the polarization direction with a composition near the crystal phase boundary (hereinafter referred to as “MPB”). thereby improving the piezoelectric constant d ₃₃ by utilizing the fact that but increased. For example, in Patent Document 1, the piezoelectric constant d ₃₃ of Ba (Ti _0.8 Zr _0.2 ) O ₃ -50% (Ba _0.7 Ca _0.3 ) TiO ₃ at 20 ° C. is 584 pC / N. Is disclosed. Furthermore, Patent Document 2 discloses that in order to improve the Q _{m of} barium titanate as a piezoelectric material at room temperature, a part of the A site of barium titanate is replaced with Ca, and a part of the B site is Mn which is an acceptor. , Fe or Cu is disclosed. Specifically, a part of the B site to form oxygen vacancies replaced with acceptor, additionally, by decreasing the mobility of the ferroelectric domain walls (pinning), to improve the Q _m.

JP 2009-215111 A JP 2010-120835 A

By the way, the increase in the degree of freedom in the polarization direction of the composition near the MPB as shown in Patent Document 1 means that it is easy to depolarize. For example, the BCTZ-based lead-free piezoelectric material of Patent Document 1 has a Curie temperature ( hereinafter referred to as _{"T C".)} is a soft material of less than 110 ° C.. This is, this means that the elastic losses during resonance driving of the BCTZ based lead-free piezoelectric material is large, the BCTZ based lead-free piezoelectric material of Patent Document 1, it is impossible to realize a large Q _m. Further, in Patent Document 2, reduction of the mobility of the formation and the ferroelectric domain walls of oxygen vacancies due to part of a substituent of the B-site by the acceptor, although improving the Q _m, there is no possible to improve the piezoelectric constant . That is, with barium titanate of Patent Document 2, a large piezoelectric constant cannot be realized. Therefore, as a conventional lead-free piezoelectric material, it does not exist which both large Q _m greater piezoelectric constant.

  An object of the present invention is to provide a piezoelectric material that has a low environmental load and has both a large piezoelectric constant and a large mechanical quality factor. Another object of the present invention is to provide a piezoelectric element, a vibration wave motor, an optical device, and an electronic device that are excellent in driving characteristics.

  In order to achieve the above object, the piezoelectric material of the present invention is a piezoelectric material including a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O, and is equivalent to an average circle of the plurality of crystal grains. A crystal grain A having a first domain having a diameter of 1.0 μm or more and 10 μm or less, a width of 300 nm or more and 800 nm or less, and a crystal grain B having a second domain having a width of 20 nm or more and 50 nm or less, It is characterized by including.

  In order to achieve the above object, the piezoelectric element of the present invention includes a first electrode, a piezoelectric material portion, and a second electrode, and the piezoelectric material constituting the piezoelectric material portion is the piezoelectric material of the present invention. Features.

  In order to achieve the above object, a vibration wave motor of the present invention includes a vibrating body provided with the piezoelectric element of the present invention and a moving body that contacts the vibrating body.

  In order to achieve the above object, an optical apparatus of the present invention includes a drive unit, and the drive unit includes the vibration wave motor of the present invention.

  In order to achieve the above object, an electronic apparatus of the present invention includes the piezoelectric element of the present invention.

  According to the present invention, it is possible to provide a piezoelectric material that has a low environmental load and has both a large piezoelectric constant and a large mechanical quality factor. In addition, according to the present invention, it is possible to provide a piezoelectric element, a vibration wave motor, an optical device, and an electronic device that are excellent in driving characteristics.

It is a figure which shows roughly the domain in each crystal grain which appears in the cross section of the piezoelectric material which concerns on this invention. It is a fragmentary perspective view which shows schematically the structure of the piezoelectric element which concerns on this invention. It is a fragmentary sectional view showing roughly the composition of the piezoelectric element concerning the present invention. It is a figure which shows roughly the structure of the vibration wave motor which concerns on this invention. It is a partial expanded sectional view which shows the structure of the principal part of the interchangeable lens barrel of the single-lens reflex camera as an optical apparatus which concerns on this invention. It is a disassembled perspective view which shows the structure of the interchangeable lens barrel of the single-lens reflex camera as an optical apparatus which concerns on this invention. 1 is an overall perspective view of a digital camera as an electronic apparatus according to the present invention. It is the schematic useful for demonstrating the ultrasonic probe which concerns on embodiment of this invention. 1 is a schematic diagram useful for explaining an ultrasonic inspection apparatus according to an embodiment of the present invention. It is Table 1 which shows the baking time of Comparative Examples 1 and 2 and Examples 1-5. It is Table 2 which shows the calculation result and measurement result of Comparative Examples 1 and 2 and Examples 1-5. It is Table 3 which shows the calculation result and measurement result of Examples 6-10. It is Table 4 which shows the calculation result and measurement result of Examples 11 and 12. It is an expanded sectional view showing a crystal grain which has both the 1st domain and the 2nd domain. It is Table 5 which shows the calculation result and measurement result of Examples 13 and 14. It is an expanded sectional view showing the 1st domain extended beyond the grain boundary of an adjacent crystal grain. It is Table 6 which shows the calculation result and measurement result of Examples 15-20. It is Table 7 which shows the other calculation result and measurement result of Examples 15-20. It is Table 8 which shows the calculation result and measurement result of Examples 21-25. It is Table 9 which shows the calculation result and measurement result of Examples 26-31. It is Table 10 which shows the calculation result and measurement result of Examples 32-37. It is Table 11 which shows the calculation result and measurement result of Examples 38-42.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the piezoelectric material according to the present invention will be described. The piezoelectric material according to the present invention is a piezoelectric material including a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O. In the piezoelectric material according to the present invention, the average equivalent circle diameter of crystal grains is 1.0 μm or more and 10 μm or less. The piezoelectric material according to the present invention includes crystal grains A having a first domain having a width of 300 nm to 800 nm and crystal grains B having a second domain having a width of 20 nm to 50 nm. The piezoelectric material is an aggregate of crystal grains, and each crystal grain contains an element constituting the piezoelectric material. In the present invention, the main component of the piezoelectric material is preferably composed of Ba, Ca, Ti, Zr, Mn, and O. The main component of the piezoelectric material is composed of Ba, Ca, Ti, Zr, Mn, and O. When the composition of the piezoelectric material is analyzed, the top six elements with respect to the molar amount are Ba, Ca, Ti, Zr, Means occupied by Mn and O. Specifically, the piezoelectric material preferably contains 98.5 mol% or more of Ba, Ca, Ti, Zr, Mn, and O in total. The crystal structure of the piezoelectric material preferably has a perovskite structure. A metal oxide having a perovskite structure (perovskite-type metal oxide) is generally expressed by a chemical formula of ABO ₃ . In the perovskite-type metal oxide, the A element and the B element occupy specific positions of unit cells called A sites and B sites as ions, respectively. For example, in the case of a cubic unit cell, the A element is located at the apex of the cube, and the B element is located at the body center. O element occupies the center of the cube as an anion of oxygen. When the unit cell is distorted in the [001], [011] or [111] direction of the cubic unit cell, the unit cell becomes a crystal lattice having a perovskite structure of tetragonal, orthorhombic or rhombohedral, respectively.

Here, when a piezoelectric material including a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O is expressed by a chemical formula of a perovskite-type metal oxide, it is expressed as the following formula (1). _{(Ba 1-x Ca x)} a (Ti 1-y-z Zr y Mn z) O 3 ... (1)

In the above formula (1), x is the ratio of Ca content (mol) to A (mol) which is the sum of Ba and Ca contents, and y is the sum of Ti, Zr and Mn contents. It is the ratio of the content (mol) of Zr to B (mol). Moreover, in said formula (1), z is ratio of content (mol) of Mn with respect to B (mol), and a is ratio (A / B) of A (mol) and B (mol) mol. The above formula (1) means a metal oxide in which the metal elements located at the A site are Ba and Ca, and the metal elements located at the B site are Ti, Zr and Mn. However, a part of Ba and Ca may be located at the B site. Similarly, some Ti, Zr and Mn may be located at the A site. In the above formula (1), the molar ratio of the B-site element and the O element is 1: 3, but even if the ratio of the element amounts (molar ratio) is somewhat different, for example, within 1%, the metal oxide If the main phase is a perovskite structure, the piezoelectric material is included in the piezoelectric material according to the present invention. Whether the metal oxide has a perovskite structure can be determined, for example, from X-ray diffraction or electron beam diffraction applied to the piezoelectric material. If the perovskite structure is the main crystal phase (main phase), the piezoelectric material is included in the piezoelectric material according to the present invention, even if the piezoelectric material contains other crystal phases as secondary agents. In the present invention, the average equivalent circle diameter of the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O of the piezoelectric material is 1.0 μm or more and 10 μm or less. By setting the average equivalent circle diameter of the crystal grains within this range, the piezoelectric material according to the present invention can have good Q _m and mechanical strength. In the present invention, the equivalent circle diameter of crystal grains means a “projected area equivalent circle diameter” generally referred to in a microscope observation method, and when observing a cross section of a piezoelectric material with a scanning electron microscope (SEM) or the like, This corresponds to the diameter of a perfect circle having an area equal to the observed projected area of crystal grains. In the present invention, the particle size measurement method is not particularly limited. For example, a piezoelectric material is processed on a piezoelectric material based on a sample preparation method such as Japanese Industrial Standard (hereinafter referred to as “JIS”) R 1633, and a cross section of the obtained piezoelectric material is obtained using a polarizing microscope, an SEM, or the like. Observe based on JIS R 1670. Thereafter, the obtained photographic image may be subjected to image processing to determine the particle size. In addition, since the optimum magnification varies depending on the target particle size, an optical microscope and an electron microscope may be used separately. The average equivalent circle diameter is obtained by averaging the equivalent circle diameters obtained for all the crystal grains in the observation field, excluding the crystal grains protruding from the observation field during observation. Although it is difficult to calculate the equivalent circle diameters of all the metal oxide crystal grains in the piezoelectric material, based on JIS Z 8827-1, etc., in order to correctly acquire the particle size distribution in the piezoelectric material, The average equivalent circle diameter is calculated by appropriately adjusting the size, part, and number.

By the way, it is considered that when the average equivalent circle diameter is larger than 1.0 μm, the square strain of the crystal structure of the piezoelectric material increases, so that the dielectric constant increases and the piezoelectric constant increases. Further, when the average equivalent circle diameter is larger than 1.0 μm, the ratio of the internal loss due to the boundary between crystal grain boundaries and domains (referred to as domain wall, domain wall, or domain wall) becomes the dielectric loss tan δ. It becomes small compared. As a result, it is considered that Q _m is a size suitable as a piezoelectric material. In general, Q _m is a coefficient representing elastic loss due to vibration when a piezoelectric material is evaluated as a vibrator, and the magnitude of Q _m is observed as the sharpness of a resonance curve in impedance measurement. That is, Q _m is a constant representing the sharpness of resonance of the vibrator. Energy Q _m is lost in the high and the vibration is small. With improved insulation and Q _m is the voltage applied to the piezoelectric material as the piezoelectric element, long-term reliability of the piezoelectric element when that has driven can be secured. It should be noted that the _{Q m} is the Electronics and Information Technology Industries Association standard, it can be measured in accordance with the EM-4501A. In general, the domain is also referred to as a domain or a magnetic domain, and is a region in which the direction of spontaneous polarization is aligned, which is observed in a band shape (striped shape) in a crystal grain by SEM or the like. Moreover, the domain in this specification is synonymous with what is called a domain structure or a domain aggregate. In general the piezoelectric material, the inverse of _{^{Q m} (Q m} ^-1) represents the internal loss, internal loss is proportional to the dielectric loss (tan [delta]). The internal loss of the ferroelectric material is expressed as the following formula (2).
Q _m ⁻¹ = C (Q _{m (SD)} ⁻¹ + k ² tan δ _(SD) ) + Q _{m (Ce)} ⁻¹ (2)

In the above formula (2), Q _{m (SD)} ⁻¹ is an intrinsic internal loss of one domain, and Q _{m (Ce)} ⁻¹ is caused by the structure of the ferroelectric material (grain boundaries, domain walls). Internal loss. Also, tan δ _(SD) is an intrinsic dielectric loss of one domain, k is an electromechanical coupling coefficient of one domain, and C is a constant.

In general, in the above formula (2), Q _{m (SD)} ⁻¹ and Q _{m (Ce)} ⁻¹ are both negligibly small, and the dielectric loss (tan δ) of the ferroelectric material is tan δ _(SD) . Since it is proportional, it is described that Q _m ⁻¹ is proportional to tan δ. However, when the average equivalent circle diameter of the crystal grains is smaller than 1.0 μm, Q _{m (Ce)} ⁻¹ becomes so large that it cannot be ignored, so that Q _m is considered to be small. Further, when the average equivalent circle diameter of the crystal grains is smaller than 10 μm, the bonding between the crystal grains increases, and the mechanical strength of the piezoelectric material increases as the density increases. The density of the piezoelectric material can be measured by, for example, the Archimedes method. Here, the ratio of the measured density (ρ _meas. ) To the theoretical density (ρ _calc. ) _Obtained from the composition and lattice constant of the piezoelectric material, that is, the relative density (ρ _calc. / Ρ _meas. ) Is 95% or more _. For example, it is considered that the piezoelectric material is sufficiently dense.

  In addition, the piezoelectric material according to the present invention includes a crystal grain A having a first domain having a width of 300 nm to 800 nm and a crystal grain B having a second domain having a width of 20 nm to 50 nm. Including. Both the first domain and the second domain may exist in the same crystal grain in the piezoelectric material, or may exist in separate crystal grains.

  FIG. 1 is a diagram schematically showing domains in each crystal grain appearing in a cross section of a piezoelectric material according to the present invention. In FIG. 1, each domain is represented by a stripe, and the width of a domain existing in the piezoelectric material according to the present invention (hereinafter simply referred to as “domain of the present invention”) corresponds to the length of the short side of these stripes. . The width of the domain can be measured in a photographic image obtained by observing a cross section of a piezoelectric material produced based on a sample preparation method such as JIS R 1633 with an SEM. In order to observe the domain of the present invention with an SEM, it is preferable to polish the cross section of the piezoelectric material into a mirror surface and deposit a thin conductive film on the cross section. As the SEM detector used for domain observation of the present invention, a secondary electron detector or a reflected electron detector is used.

In general, Q _m and the piezoelectric constant is a trade-off, the piezoelectric constant decreases when Q _m is increased, the Q _m becomes smaller that the piezoelectric constant increases known reversed. In contrast, in the present invention, by adjusting the width of the domains in the crystal grains contained in the piezoelectric material, to eliminate the trade-off of Q _m and the piezoelectric constant, a large piezoelectric constant (in particular, a large piezoelectric constant (Absolute value of d ₃₁ ) and a large Q _m are provided. Specifically, the piezoelectric material according to the present invention has a crystal grain A having a first domain contributing to an increase in Q _{m and} an increase in absolute value of a piezoelectric constant d ₃₁ (hereinafter simply referred to as “d ₃₁ ”). And a crystal grain B having a second domain contributing to. Since the domain inversion occurs relatively easily in the second domain, the crystal grains B having the second domain enter between the crystal grains A having the first domain. It is thought that distortion is reduced. Accordingly, in the piezoelectric material according to the present invention, the absolute value of d ₃₁ increases.

Here, consider the case where the width of the second domain is 50 nm or less in a crystal grain containing Ba, Ca, Ti, Zr, Mn, and O and having an average equivalent circle diameter of 1.0 μm or more and 10 μm or less. . In this case, the density of the 90 ° domain wall having high electric field response is increased. As a result, the piezoelectric material is considered that the absolute value of the d ₃₁ and the dielectric constant is increased becomes larger. Next, consider the case where the width of the second domain is 20 nm or more. In this case, it is considered that the crystal structure of each crystal grain is stabilized and the remanent polarization is increased. As a result, it is considered that the absolute value of d ₃₁ is a suitable value in the piezoelectric material. Therefore, in the present invention, the width of the second domain is set to be 20 nm or more and 50 nm or less. In general, d ₃₁ of the piezoelectric material is based on the standard of the Japan Electronics and Information Technology Industries Association (JEITA EM-4501A) based on the measurement results of the resonance frequency and the anti-resonance frequency obtained using a commercially available impedance analyzer in the same manner as Q _m. Can be obtained by calculation. Hereinafter, this calculation method of d ₃₁ is referred to as resonance / anti-resonance method. When the absolute value of d ₃₁ is smaller than 50 pm / V, it is necessary to supply a large electric power to the piezoelectric device when driving the piezoelectric device including the piezoelectric material. Therefore, the absolute value of d ₃₁ preferable as a piezoelectric material is 50 pm / V or more. In particular, when the absolute value of d ₃₁ is 80 pm / V or more, power consumption during driving of the piezoelectric device can be suppressed, and the piezoelectric material is practically used. Suitable. _Further, when the absolute value of _{d 31} is equal to or greater than 90 Pm/V, piezoelectric devices, with better performance.

Further, a case where the width of the first domain is 800 nm or less in a crystal grain containing Ba, Ca, Ti, Zr, Mn, and O and having an average equivalent circle diameter of 1.0 μm to 10 μm will be considered. In this case, it is considered that _Qm increases as the residual stress generated between crystal grains decreases due to domain switching of non-180 degree domains. Next, consider the case where the width of the first domain is 300 nm or more. In this case, since the internal loss due to the grain boundaries and the domain wall is reduced, it is considered to Q _m is increased. Therefore, in the present invention, the width of the first domain is set to be 300 nm or more and 800 nm or less. Incidentally, the value of Q _m is less than 600, the power consumption when driving as a resonant device with a piezoelectric material the piezoelectric element is increased. Thus, for the value of Q _m of a piezoelectric material according to the present invention, the value of Q _m is preferably 600 or more. Particularly, the extreme increase in the power consumption value of Q _m is 800 or more because they do not occur, and more preferred. Furthermore, the value of Q _m becomes 1000 or more, it is possible to have a good performance as a piezoelectric element.

  In this embodiment, having the first domain means that one or more domains having a width of 300 nm or more and 800 nm or less exist in a single crystal grain in the above-described microscope observation. Having the second domain means that one or more domains having a width of 20 nm or more and 50 nm exist in a single crystal grain in the above-described microscopic observation. The presence of 5% by number or more of crystal grains A having the first domain means that a domain having a width of 300 nm or more and 800 nm or less when the number of all crystal grains in the observation field is 100 in the above-described microscope observation. It means that 5 or more crystal grains A are present. Further, the presence of 5% by number or more of crystal grains B having the second domain means that the width is 20 nm or more and 50 nm or less when the number of all crystal grains in the observation field is 100 in the above-described microscope observation. It means that there are 5 or more crystal grains B having domains.

As described above, if the domain width is 300 nm or more and 800 nm or less, Q _m is considered to be large. If the domain width is 20 nm or more and 50 nm or less, the absolute value of d ₃₁ is considered to be large. Therefore, in the present invention, in the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O of the piezoelectric material, there are 5% by number or more of crystal grains A having the first domain, and the second domain has the second domain. It is set so that there are 5% by number or more of crystal grains B having. As a result, in the piezoelectric material, the number of crystal grains contributing to an increase in Q _m can be increased, and at the same time, the number of crystal grains contributing to an increase in the absolute value of d ₃₁ can be increased, and Q _m is 800 or more, and d ₃₁ A suitable piezoelectric material having an absolute value of 80 pm / V or more can be obtained. In particular, the crystal grain B having the second domain is 10% by number or more and 50% by number or less of the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O, and the piezoelectric material according to the present invention. more preferable because the absolute value of the d ₃₁ becomes larger. In addition, the crystal material A having the first domain is 10% by number or more and 50% by number or less of the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O, and the piezoelectric material according to the present invention. more preferable because Q _m Gayori becomes large. In counting the number of crystal grains A having the first domain and the number of crystal grains B having the second domain, it is desirable to increase the counting accuracy by observing more crystal grains. Specifically, the width of a domain is measured in at least 200, particularly 1000 or more crystal grains, and the number of crystal grains A having a first domain and crystal grains B having a second domain is counted. It is desirable.

Further, a case where the first domain and the second domain are included in the same crystal grain will be considered. In this case, an increase in Q _{m and} an increase in the absolute value of d ₃₁ occur more effectively in synergy. Therefore, in the present invention, it is more preferable that the piezoelectric material includes crystal grains having both the first domain and the second domain. In particular, when the piezoelectric material contains 5% by number or more of crystal grains having both the first domain and the second domain, the Q _m is 900 or more and the absolute value of d ₃₁ is 85 pm / V or more. More preferable as a material. A crystal grain has both the first domain and the second domain means that a domain having a width of 300 nm or more and 800 nm or less and a domain having a width of 20 nm or more and 50 nm or less are each 1 in the same crystal grain. Means that there is more than one. Note that the crystal grain A having the first domain may also have the second domain, and the crystal grain B having the second domain may also have the first domain. Further, consider the case where the first domain extends beyond the grain boundary of adjacent crystal grains in the piezoelectric material. In this case, the residual stress generated between the crystal grains becomes smaller due to the domain switching of the non-180 degree domain, and the internal loss due to the grain boundary becomes smaller. Thus, the effect of increasing the Q _m becomes larger. Therefore, in the present invention, it is more preferable that the piezoelectric material has the first domain extending beyond the grain boundary between adjacent crystal grains. The first domain extends beyond the grain boundary of the crystal grain. A domain having a width of 300 nm or more and 800 nm or less has a width of the same level while maintaining the same domain width. What extends to more than one crystal grain means that it exists in the field of view. At this time, the domain exists in two or more crystal grains in the same dielectric polarization direction. Consider the case where the Pb component contained in the piezoelectric material is less than 1000 ppm. In this case, for example, even if a piezoelectric material or an element or device using the piezoelectric material is discarded and exposed to acid rain or left in a harsh environment, the lead component in the piezoelectric material may have an adverse effect on the environment. Can be reduced. Therefore, in the piezoelectric material according to the present invention, the Pb component contained is preferably less than 1000 ppm.

Next, the composition ratio of the piezoelectric material according to the present invention will be described. First, consider the case of containing Ca. In this case, the phase transition temperature (T _to ) from tetragonal to orthorhombic at the time of temperature decrease and the phase transition temperature (T _ot ) from orthorhombic to tetragonal at the time of temperature decrease are decreased. In particular, when the value of x, which is the ratio of the Ca content (mol) to A (mol), which is the sum of the Ba and Ca contents, is 0.02 or more and 0.10 or less, T _to and _Tot Approaches room temperature. Further, it exhibits a large absolute value of d ₃₁ (for example, 150 pm / V or more) near room temperature (for example, 0 ° C. to 40 ° C.). When the value of x is larger than 0.10, T _to and _Tot are lowered to less than 0 ° C., and the temperature dependence of the piezoelectric constant is reduced. On the other hand, when x is smaller than 0.30, solid solution of Ca is promoted, and the firing temperature can be lowered. Therefore, in the present invention, in the above formula (1), the value of x is more preferably 0.02 ≦ x ≦ 0.30.

By the way, the piezoelectric material according to the present invention causes successive phase transitions to rhombohedral, orthorhombic, tetragonal and cubic as the temperature rises from a low temperature. The phase transition in this embodiment refers to a phase transition exclusively from orthorhombic to tetragonal or from tetragonal to orthorhombic. The phase transition temperature can be evaluated in the same measurement method and T _C which will be described later, in this embodiment, a value obtained by differentiating the dielectric constant sample temperature to the phase transition temperature to the temperature at which the maximum. The crystal system can be evaluated by X-ray diffraction, electron beam diffraction, Raman scattering, or the like. Near the phase transition temperature, the dielectric constant and the electromechanical coupling coefficient k are maximized, and the Young's modulus is minimized. The piezoelectric constant is a function of these three parameters, and shows a maximum value or an inflection point near the phase transition temperature. Here, the phase transition temperature is far from the operating temperature range of the piezoelectric device. For example, when the phase transition temperature is −50 ° C. or higher and −10 ° C. or lower, the temperature dependence of the piezoelectric performance in the operating temperature range is reduced. Therefore, it is more preferable from the viewpoint of controlling the device. However, as described above, since the piezoelectric constant shows a maximum value near the phase transition temperature, the controllability of the device and the large piezoelectric constant are compatible by controlling the relationship between the phase transition temperature and the operating temperature range by the composition of the piezoelectric material. It is desirable to do. From this viewpoint, it is more preferable that x is 0.20 or less because the piezoelectric constant is high and the temperature dependence of the piezoelectric performance is suppressed.

In the present embodiment, the temperature dependence of d ₃₁ and Q _m of the piezoelectric element measured using the resonance / anti-resonance method may be measured as follows. Specifically, a piezoelectric element is placed in a thermostatic chamber, and d ₃₁ and Q _m are measured by a resonance / anti-resonance method while changing the temperature of the atmosphere. The rate of change of temperature is not particularly limited, but may be changed at 1 to 10 ° C./min. After changing the temperature, hold the temperature constant until the temperature of the piezoelectric element follows the ambient temperature, and then measure the piezoelectric constant and the electromechanical quality factor using the resonance / anti-resonance method. Since it becomes high, it is desirable to measure in this way. The time for keeping the temperature constant is not particularly limited, but is preferably 1 to 10 minutes.

Consider the case of containing Zr. In this case, the temperature of T _to or _Tot increases. In particular, by setting the value of y, which is the molar ratio of Zr to the sum of the moles of Ti, Zr and Mn in the above formula (1), to 0.01 or more, T _to and _Tot become close to room temperature, and The piezoelectric constant in the temperature range (for example, −30 ° C. to 60 ° C.) increases. As a result, electric power necessary for driving a piezoelectric element using a piezoelectric material, a piezoelectric element having a laminated structure, a vibration wave motor, an optical device, an electronic device, and the like can be suppressed. On the other hand, by setting y 0.095 or less, T _C, for example, be 100 ° C. or more high temperature, since the depolarization when used in high temperature is further suppressed, the guaranteed operation temperature range of the piezoelectric device Becomes wider and the deterioration of the piezoelectric constant with time becomes smaller. Therefore, in the present invention, in the above formula (1), the value of y is more preferably 0.01 ≦ y ≦ 0.095. T _C is the temperature at which piezoelectricity of the piezoelectric material disappeared at that temperature or more. In the present embodiment, a ferroelectric phase (tetragonal phase) and the temperature at which dielectric constant becomes maximum at the phase transition temperature near the paraelectric phase (cubic phase) and T _C. The dielectric constant is measured by applying an alternating electric field having a frequency of 1 kHz and an electric field strength of 10 V / cm by using a parallel plate capacitor method, for example, using an impedance analyzer.

Next, the case where _TC is 100 ° C. or higher in the piezoelectric material according to the present invention will be considered. In this case, even under the severe condition of 80 ° C. assumed in a car in summer, the piezoelectricity can be maintained without loss, and a stable piezoelectric constant and Q _m can be obtained. Therefore, in the present invention, it is more preferably T _C is 100 ° C. or higher. Also, consider z which is the molar ratio of Mn to the sum of the number of moles of Ti, Zr and Mn in the above formula (1). Mn has a property that the valence fluctuates between divalent and tetravalent, and plays a role of compensating for a charge balance defect in the piezoelectric material. If the value of z is 0.003 or more, the residual stress of oxygen vacancy concentration in the crystal lattice of the piezoelectric material is increased, the domain switching non-180 degree domain generated between the crystal grains is reduced, Q _m It is thought that the value of increases more. On the other hand, when the value of z is 0.012 or less, solid solution of Mn can be promoted and the insulation resistance can be further increased. In particular, the value of z is, when in the range of 0.003 ≦ z ≦ 0.012, the value of _{Q m} becomes 1200 or more, more preferably. Therefore, in the present invention, the value of z in the above formula (1) is more preferably 0.003 ≦ z ≦ 0.012. Here, Mn is not limited to metal Mn, but may be contained in the piezoelectric material as a Mn component, and the form of the inclusion is not limited. For example, it may be dissolved in the B site or may be contained in the grain boundary. Alternatively, the Mn component may be included in the piezoelectric material in the form of a metal, ion, oxide, metal salt, complex, or the like. Moreover, it is preferable that Mn exists also from a viewpoint of insulation and sintering ease. The valence of Mn can generally be 4+, 2+, 3+, but when the valence of Mn is lower than 4+, Mn becomes an acceptor. When Mn is present in the perovskite structure crystal as an acceptor, oxygen vacancies are formed in the crystal. Oxygen vacancies to form a defect dipole, it is possible to improve the Q _m of a piezoelectric material. Therefore, in the present invention, it is preferable that the valence of Mn is lower than 4+. In order for Mn to exist at a valence lower than 4+, it is preferable that a trivalent element exists at the A site. A preferred trivalent element at this time is Bi. Here, the valence of Mn can be evaluated by measuring the temperature dependence of the magnetic susceptibility.

In the present invention, to include subcomponent piezoelectric material consists of Bi, to improve the Q _m at low temperature, more preferably. In particular, in the above formula (1), when the Bi content (mol) with respect to the sum of A (mol) and B (mol) is 0.15% or more and 0.40% or less, a low temperature region, for example, − Q _{m at} 30 ° C. increases to, for example, 350 or more. Thereby, in a piezoelectric device using a piezoelectric material, control in a low temperature region becomes easy. In the present invention, in the above formula (1), the value of a indicating the ratio of A (mol) to B (mol) is more preferably 0.98 or more and 1.01 or less. When the value of a is 0.98 or more and 1.01 or less, the piezoelectric material is easily densified, the mechanical strength is improved, and the temperature necessary for the growth of crystal grains can be fired in a general firing furnace 1500 Decrease below ℃.

  Next, the form of the piezoelectric material according to the present invention will be described. The form of the piezoelectric material according to the present invention is not particularly limited and may be any form such as ceramics, powder, single crystal, thin film, slurry, granulated powder, and molded body, but is preferably ceramic. “Ceramics” in the present embodiment represents a so-called polycrystal, an aggregate (bulk body) of crystal particles whose basic component is a metal oxide and is baked (hardened) by heat treatment (sintered). In addition, the ceramic processed after sintering is also included.

  Next, a method for manufacturing a piezoelectric material according to the present invention will be described. The manufacturing method of the piezoelectric material according to the present invention is not particularly limited, but a typical manufacturing method will be exemplified below.

  First, the raw material powder of the piezoelectric material according to the present invention will be described. As a method for producing a raw material powder of a piezoelectric material according to the present invention, a general method of sintering solid powders such as oxides, carbonates, nitrates and oxalates containing constituent elements under normal pressure can be employed. . Solid powder here is comprised from metal compounds, such as Ba compound, Ca compound, Ti compound, Zr compound, Mn compound, Bi compound. In particular, when a perovskite-type metal oxide is mixed with all of the Ba compound, Ca compound, Ti compound, Zr compound and Mn compound, an effect of refining crystal grains after sintering can be obtained. Generation of cracks and chipping during processing can be further suppressed. Therefore, it is preferable to mix the Ba compound, Ca compound, Ti compound, Zr compound, and Mn compound by using a perovskite metal oxide. Here, usable Ba compounds include barium oxide, barium carbonate, barium oxalate, barium acetate, barium nitrate, barium titanate, barium zirconate, barium zirconate titanate and the like. Examples of usable Ca compounds include calcium oxide, calcium carbonate, calcium oxalate, calcium acetate, calcium titanate, and calcium zirconate. Further, usable Ti compounds include titanium oxide, barium titanate, barium zirconate titanate, calcium titanate and the like. Examples of usable Zr compounds include zirconium oxide, barium zirconate, barium zirconate titanate, and calcium zirconate. Further, usable Mn compounds include manganese carbonate, manganese monoxide, manganese dioxide, tetramanganese trioxide, manganese acetate and the like. Bi compounds that can be used include bismuth oxide and the like.

  In the present embodiment, the raw material for adjusting a indicating the ratio of the sum of the number of moles of Ti, Zr, and Mn to the sum of the number of moles of Ba and Ca of the piezoelectric material in the above formula (1) is particularly It is not limited. The effect of adjusting a is the same for any of the Ba compound, Ca compound, Ti compound, Zr compound, and Mn compound.

  Next, the process of obtaining the molding granules will be described. The method for granulating the raw material powder of the piezoelectric material according to the present invention to obtain the molding granules is not particularly limited. Examples of binders that can be used when granulating include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), and acrylic resins. The amount of the binder to be added is preferably 1 to 10 parts by weight, and more preferably 2 to 5 parts by weight from the viewpoint of increasing the density of the molded body. The raw material powder may be granulated from a mixed powder obtained by mechanically mixing a Ba compound, Ca compound, Ti compound, Zr compound and Mn compound, and after calcining these compounds at about 800 to 1300 ° C., the raw material powder May be granulated. Or after calcining Ba compound, Ca compound, Ti compound, and Zr compound, Mn compound may be added simultaneously with a binder. From the viewpoint that the granular granulated powder for molding can be made more uniform in particle size, the most preferred granulation method is a spray drying method.

  Then, the process of obtaining a molded object is demonstrated. The method for producing a molded body of the piezoelectric material according to the invention is not particularly limited. The compact is a solid material made from raw material powder, granulated powder, or slurry. As a means for forming a molded body, uniaxial pressing, cold isostatic pressing, warm isostatic pressing, cast molding, extrusion molding, and the like can be used.

  Next, a process for obtaining a piezoelectric material will be described. In the present invention, the piezoelectric material is obtained by sintering, but the method for sintering the piezoelectric material is not particularly limited. Examples of the sintering method include sintering by an electric furnace, sintering by a gas furnace, current heating method, microwave sintering method, millimeter wave sintering method, HIP (hot isostatic pressing) and the like. The sintering furnace used in the electric furnace or gas sintering may be a continuous furnace or a batch furnace. Further, the sintering temperature of the piezoelectric material in the sintering method is not particularly limited. Any temperature may be used as long as each compound reacts and crystal is sufficiently grown. In particular, a preferable sintering temperature is 1200 ° C. or more and 1500 ° C. or less, and a more preferable sintering temperature is 1250 ° C. or more and 1450 ° C. or less. A piezoelectric material sintered in this temperature range exhibits good piezoelectric performance. In order to stabilize the characteristics of the piezoelectric material obtained by sintering with good reproducibility, it is preferable to perform the sintering treatment for 2 hours to 24 hours with the sintering temperature kept constant within the above range. At this time, a sintering method such as a two-stage sintering method may be used, but a method with no rapid temperature change is preferable in consideration of productivity.

  Next, a thin film made of the piezoelectric material according to the present invention will be described. When the piezoelectric material according to the present invention is used as a film formed on a substrate, the thickness of the piezoelectric material is preferably 400 nm or more and 10 μm or less, more preferably 500 nm or more and 3 μm or less. This is because a sufficient electromechanical conversion function as a piezoelectric element can be obtained by setting the film thickness of the piezoelectric material to 400 nm or more and 10 μm or less. Here, the method for forming a thin film made of a piezoelectric material is not particularly limited. For example, chemical solution deposition method (CSD method), sol-gel method, metal organic chemical vapor deposition method (MOCVD method), sputtering method, pulse laser deposition method (PLD method), hydrothermal synthesis method, aerosol deposition method (AD Law). In the chemical solution deposition method or the sputtering method, the film formation area can be easily increased, and therefore the chemical solution deposition method or the sputtering method is the most preferable lamination method. The substrate used for the piezoelectric material according to the present invention is preferably a single crystal substrate cut and polished on the (001) plane or the (110) plane. By using a single crystal substrate cut and polished on a specific crystal plane, a thin film of piezoelectric material provided on the substrate surface can be strongly oriented in the same direction.

  Next, the piezoelectric element according to the present invention will be described. FIG. 2 is a partial perspective view schematically showing the configuration of the piezoelectric element according to the present invention. In FIG. 2, the piezoelectric element 200 includes at least an upper electrode 201, a piezoelectric material portion 202, and a lower electrode 203. In the piezoelectric element 200, the piezoelectric material according to the present invention is used as the piezoelectric material constituting the piezoelectric material portion 202. By using the piezoelectric material according to the present invention as the piezoelectric material constituting the piezoelectric material portion 202, the piezoelectric characteristics can be evaluated. The upper electrode 201 and the lower electrode 203 are made of a conductive layer having a thickness of about 5 nm to 10 μm. The material of the conductive layer is not particularly limited, and any material that is usually used for a piezoelectric element may be used. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu, and compounds thereof can be used. The upper electrode 201 and the lower electrode 203 may be made of one of the metals and compounds described above, or may be a laminate of two or more of these. Further, the upper electrode 201 and the lower electrode 203 may be made of different materials. The manufacturing method of the upper electrode 201 and the lower electrode 203 is not limited, and may be formed by baking a metal paste, or may be formed by sputtering, vapor deposition, or the like. Further, the upper electrode 201 and the lower electrode 203 may be used after being patterned into a desired shape.

  Next, the polarization of the piezoelectric element according to the present invention will be described. In the piezoelectric element, when the polarization axes are aligned in a certain direction, the piezoelectric constant of the piezoelectric element increases. Therefore, in the piezoelectric element, the polarization axes are preferably aligned in a certain direction. The fact that the polarization axes are aligned in a certain direction in a piezoelectric material or a piezoelectric element can be confirmed through confirmation of the presence of residual polarization in the PE (polarization-electric field) hysteresis measurement. The polarization method of the piezoelectric element according to the present invention is not particularly limited as long as the crystal grain A having the first domain and the crystal grain B having the second domain can coexist. The polarization may be performed in the air or in silicone oil. The temperature at the time of polarization is preferably about room temperature (for example, 25 ° C.) to 150 ° C. However, because the composition of the piezoelectric material constituting the piezoelectric element and the manufacturing method differ in the distribution of the domain width existing in the piezoelectric material before polarization and the domain wall pinning effect due to oxygen vacancies generated by the addition of Mn. The optimum conditions for polarization are also different. In particular, the higher the polarization temperature and the longer the polarization time, the easier the domain width becomes. For example, when the width of most domains of the piezoelectric material before polarization already matches the width of the second domain, the width of the domain increases as the polarization temperature increases or the polarization time increases in polarization. The number of second domains is reduced. In particular, when the polarization temperature is too high, or when the polarization time is too long, the domain width becomes too large, and the second domain may be lost. On the other hand, when the polarization temperature is low or when the polarization time is short, domain growth is suppressed, so that even if the second domain remains sufficiently, the first domain may hardly be generated.

In the polarization, when only the polarization time and the polarization temperature are used as parameters, the width of the domain basically increases according to the polarization time and the polarization temperature. Therefore, the crystal grains A having the first domain and the second domain are It becomes difficult to control the coexisting crystal grains B to be present. Therefore, it is preferable to control the polarization using parameters other than the polarization time and the polarization temperature. For example, a first polarization processing, to produce a first domain by applying a DC voltage to the piezoelectric element at T _C around the temperature, then, once cooled a piezoelectric element, thereby stabilizing the first domain . Then, as a subsequent second polarization process, a weak DC voltage or a pulsed voltage is applied for a short time at a temperature from room temperature to less than 80 ° C. in the opposite direction to the first polarization process to generate a second domain. It is possible. In this case, the electric field applied in the first polarization treatment is preferably 800 V / mm to 2.0 kV / mm, and the electric field applied in the second polarization treatment uses a lower voltage. For example, the electric field applied in the second polarization process is appropriately adjusted in combination with the polarization time, the polarization temperature, and the like so that the second domain has a desired distribution and number. Further, applied as the other polarization, for example, as the first polarization processing, T _C slightly over lower temperatures (e.g., about 10 ° C.) a relatively small (e.g., 650V / mm) of the DC voltage to the piezoelectric element To generate a first domain. As a subsequent second polarization process, there is a method of generating a second domain by applying a weak DC voltage or a pulsed voltage in the opposite direction to the first polarization process while cooling at a constant speed. Conceivable.

  Next, the insulating property of the piezoelectric material according to the present invention will be described. The tan δ at a frequency of 1 kHz at 25 ° C. of the piezoelectric material according to the present invention is preferably 0.006 or less. The resistivity at 25 ° C. is preferably 1 GΩcm or more. When tan δ is 0.006 or less, stable operation can be obtained even when an electric field of maximum 500 V / cm is applied to the piezoelectric material under the driving conditions of the piezoelectric element. In addition, when the resistivity is 1 GΩcm or more, a polarization effect can be sufficiently obtained. The tan δ and the resistivity can be measured by applying an AC electric field having a frequency of 1 kHz and an electric field strength of 10 V / cm to the piezoelectric element using an impedance analyzer.

  Next, the insulating property of the piezoelectric element according to the present invention will be described. FIG. 3 is a partial cross-sectional view schematically showing the configuration of the piezoelectric element according to the present invention. In FIG. 3, a piezoelectric element 300 includes piezoelectric material layers 301 and at least one internal electrode 302, and the piezoelectric material layers 301 and at least one internal electrode 302 are alternately stacked. The piezoelectric material layer 301 is made of the above piezoelectric material. As the electrode layer, each of the upper electrode 303 and the lower electrode 304 is provided in addition to at least one internal electrode 302. For example, the piezoelectric element 300 may be a stacked structure in which two piezoelectric material layers 301 and one internal electrode 302 are alternately stacked (FIG. 3A). An upper electrode 303 and a lower electrode 304 are disposed on the upper surface and the lower surface of the laminated structure, respectively. The number of piezoelectric material layers 301 and internal electrodes 302 included in the piezoelectric element 300 is not limited to the example illustrated in FIG. For example, the piezoelectric element 300 may be a stacked structure in which nine piezoelectric material layers 301 and eight internal electrodes 302 are alternately stacked (FIG. 3B). An upper electrode 303 and a lower electrode 304 are also disposed on the upper surface and the lower surface of the laminated structure, respectively. Further, in order to short-circuit each layer of the internal electrode 302, an external electrode 305 and an external electrode 306 are arranged on both sides, respectively. The size and shape of the internal electrode 302, the upper electrode 303, the lower electrode 304, and the external electrodes 305 and 306 are not necessarily the same as the size and shape of the piezoelectric material layer 301, and each electrode is divided into a plurality of parts. It may be. The internal electrode 302, the upper electrode 303, the lower electrode 304, and the external electrodes 305 and 306 are each made of a conductive layer having a thickness of about 5 nm to 10 μm. The material of each electrode is not particularly limited, and any material that is usually used for a piezoelectric element may be used. Examples thereof include metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu, and compounds thereof. In particular, the internal electrode 302 and the external electrodes 305 and 306 may be made of one of these materials, or may be a mixture of two or more or two or more alloys. Further, the internal electrode 302 and the external electrodes 305 and 306 may be formed by stacking two or more of these materials. Further, each of the electrodes 302 to 306 may be made of different materials.

  In the piezoelectric element 300, in particular, the internal electrode 302 includes Ag and Pd, and the weight ratio M1 / M2 between the Ag content weight M1 and the Pd content weight M2 is 0.25 ≦ M1 / M2 ≦ 4.0. Is preferable, and 0.3 ≦ M1 / M2 ≦ 3.0 is more preferable. If the weight ratio M1 / M2 is less than 0.25, the sintering temperature of the internal electrode is increased, which is not desirable. On the other hand, if the weight ratio M1 / M2 is greater than 4.0, the internal electrodes are island-like and are not uniform in the plane, which is not desirable. In order to reduce the electrode material, the internal electrode 302 preferably contains at least one of Ni and Cu. When at least one of Ni and Cu is used for the internal electrode 302, the piezoelectric element 300 is preferably fired in a reducing atmosphere. Further, as shown in FIG. 3B, the layers of the internal electrode 302 may be short-circuited with each other in order to align the phases of the drive voltages. For example, half of the layers of the internal electrode 302 and the upper electrode 303 may be short-circuited by the external electrode 305, and the other half of the layer of the internal electrode 302 and the lower electrode 304 may be short-circuited by the external electrode 306. Furthermore, each layer 2 of the internal electrode 30 that is short-circuited with the upper electrode 303 and each layer of the internal electrode 302 that is short-circuited to the lower electrode 304 may be alternately arranged. In addition, the form of the short circuit of each electrode is not limited to the form shown in FIG. An electrode or wiring for short-circuiting may be provided on the side surface of the laminated structure, or a through-hole penetrating each piezoelectric material layer 301 is provided, and a conductive material is provided inside the through-hole to short-circuit each electrode. Also good.

  Next, the vibration wave motor according to the present invention will be described. FIG. 4 is a diagram schematically showing the configuration of the vibration wave motor according to the present invention. A vibration wave motor 400 as a vibration wave motor according to the present invention includes a vibrator 401 (vibrating body) and a rotor 402 (moving body) that pressurizes and contacts a sliding surface of the vibrator 401 with a pressure applied by a pressure spring. And an output shaft 403 provided integrally with the rotor 402 (FIG. 4A). The vibrator 401 includes a metal elastic ring 404 and a piezoelectric element 405. The piezoelectric element 405 is bonded to the elastic ring 404 with an organic adhesive 406 (epoxy or cyanoacrylate adhesive). The The piezoelectric element 405 has, for example, a single layer structure (there is only one piezoelectric material layer) like the piezoelectric element 200 described above, and is composed of a piezoelectric material sandwiched between an upper electrode and a lower electrode. . By the way, when a voltage is applied to the piezoelectric material, the piezoelectric material expands and contracts due to the piezoelectric lateral effect. Here, when an elastic body such as metal is bonded to the piezoelectric element, the elastic body is bent by expansion and contraction of the piezoelectric material, and a bending traveling wave is generated in the elastic body. The vibration wave motor 400 is driven using this bending traveling wave. Specifically, when a two-phase alternating voltage whose phase is different by an odd multiple of π / 2 is applied to the piezoelectric element 405, a bending traveling wave is generated in the vibrator 401, on the sliding surface of the vibrator 401. Each of the points performs an elliptical motion. When the rotor 402 is pressed against the sliding surface of the vibrator 401, the rotor 402 receives a frictional force from the vibrator 401 and rotates in a direction opposite to the bending traveling wave. In the vibration wave motor 400, since the output shaft 403 is joined to a driven body (not shown), the driven body is driven by the output shaft 403 by the rotational force of the rotor 402.

  A vibration wave motor 407 as another example of the vibration wave motor according to the present invention includes a vibrator 408 and a rotor 410 that is in pressure contact with the vibrator 408 by a pressure spring 409 (FIG. 4B). )). The vibrator 408 includes a metal elastic body 411 formed of a divided cylindrical body, and a piezoelectric element 412 sandwiched between the cylindrical bodies of the metal elastic body 411. The piezoelectric element 412 has, for example, a laminated structure (a plurality of piezoelectric material layers exist) like the piezoelectric element 300 described above, and an upper electrode and a lower electrode are arranged outside the laminated structure, and the laminated structure Inside, a plurality of layers of internal electrodes are alternately arranged with each piezoelectric material layer. Each cylindrical body of the metal elastic body 411 is fastened by a bolt, and sandwiches and fixes the piezoelectric element 412 to constitute the vibrator 408. By applying a two-phase alternating voltage having different phases to the piezoelectric element 412, the vibrator 408 excites two vibrations orthogonal to each other. These two vibrations are combined to form a circular vibration for driving the tip of the vibrator 408. In the vibration wave motor 407, a constricted circumferential groove 413 is formed on the top of the vibrator 408 to increase the displacement of the circular vibration. Since the rotor 410 is in pressure contact with the vibrator 408, a frictional force for driving is obtained from the vibrator 408. The rotor 410 is rotatably supported by a bearing (not shown).

  Next, the optical apparatus according to the present invention will be described. FIG. 5 is a partial enlarged cross-sectional view showing a configuration of a main part of an interchangeable lens barrel of a single-lens reflex camera as an optical apparatus according to the present invention. FIG. 6 is an exploded perspective view showing a configuration of an interchangeable lens barrel of a single-lens reflex camera as an optical apparatus according to the present invention. 5 and 6, the interchangeable lens barrel 500 includes a fixed barrel 501, a straight guide barrel 502, and a front group barrel 503 as fixing members, and these fixing members are fixed to a detachable mount 504 of the camera. Is done. In addition, the interchangeable lens barrel 500 includes a focus lens 505 and a rear group barrel 506 that holds the focus lens 505 (FIG. 5A). A rectilinear guide groove 507 for the focus lens 505 in the optical axis direction is formed in the rectilinear guide tube 502. Cam rollers 508 and 509 protruding outward in the radial direction are fixed to the rear group barrel 506 by a shaft screw 510, and the cam roller 508 is fitted in the rectilinear guide groove 507. A cam ring 511 is rotatably fitted to the inner periphery of the rectilinear guide tube 502. When the roller 512 fixed to the cam ring 511 is fitted in the circumferential groove 513 of the straight guide tube 502, the relative movement of the straight guide tube 502 and the cam ring 511 in the optical axis direction is restricted and integrated in the optical axis direction. Move on. A cam groove 514 for the focus lens 505 is formed in the cam ring 511, and the above-described cam roller 509 is fitted into the cam groove 514. A rotation transmission ring 516 that is held by a ball race 515 so as to be rotatable at a fixed position with respect to the fixed cylinder 501 is disposed on the outer peripheral side of the fixed cylinder 501. The rotation transmission ring 516 has a shaft 517 extending radially, and a roller 518 is rotatably held on each shaft 517. The large diameter portion 519 of the roller 518 comes into contact with the mount side end surface 521 of the manual focus ring 520 (FIG. 5B). Further, the small diameter portion 522 of the roller 518 is in contact with the bonding member 523. In the interchangeable lens barrel 500, six rollers 518 are arranged at equal intervals along the outer periphery of the rotation transmission ring 516, and are rotatably held on the respective shafts 517.

  A low friction sheet 524 is disposed on the inner diameter portion of the manual focus ring 520, and the low friction sheet 524 is sandwiched between the mount side end face 525 of the fixed cylinder 501 and the front end face 526 of the manual focus ring 520. Further, the outer diameter surface of the low friction sheet 524 has a ring shape and is fitted to the inner diameter 527 of the manual focus ring 520. Further, the inner diameter 527 of the manual focus ring 520 is fitted to the outer diameter portion 528 of the fixed cylinder 501. The low friction sheet 524 reduces friction when the manual focus ring 520 rotates relative to the fixed cylinder 501 around the optical axis. The large diameter portion 519 of the roller 518 and the mount side end surface 521 of the manual focus ring 520 are brought into contact with each other by the force with which the wave washer 529 presses the vibration wave motor 530 forward of the lens. The vibration wave motor 530 of the interchangeable lens barrel 500 constitutes a drive unit of the interchangeable lens barrel 500 and has, for example, a structure similar to that of the vibration wave motor 400. Further, due to the force with which the wave washer 529 presses the vibration wave motor 530 forward of the lens, the small diameter portion 522 of the roller 518 and the bonding member 523 come into contact with each other with an appropriate pressure applied. The wave washer 529 is restricted from moving in the mounting direction by a washer 531 that is bayonet-coupled to the fixed cylinder 501. The spring force (biasing force) generated by the wave washer 529 is transmitted to the vibration wave motor 530 and further to the roller 518, and presses the manual focus ring 520 against the mount side end surface 525 of the fixed barrel 501. That is, the manual focus ring 520 is incorporated into the interchangeable lens barrel 500 in a state where the manual focus ring 520 is pressed against the mount side end surface 525 of the fixed barrel 501 through the low friction sheet 524. Therefore, when the vibration wave motor 530 is rotationally driven with respect to the fixed cylinder 501, the joining member 523 is brought into frictional contact with the small-diameter portion 522 of the roller 518, so that the roller 518 rotates about the shaft 517. Thereby, the rotation transmission ring 516 rotates around the optical axis (autofocus operation). Consider a case where a rotational force around the optical axis is applied to the manual focus ring 520 from a manual operation input unit (not shown). In this case, the mount side end surface 521 of the manual focus ring 520 is in pressure contact with the large-diameter portion 519 of the roller 518, so that the roller 518 rotates around the shaft 517 due to frictional force. This also rotates the rotation transmission ring 516 around the optical axis. At this time, the rotation of the vibration wave motor 530 is suppressed by the frictional holding force between the rotor 532 and the stator 533 (manual focus operation).

  Two focus keys 534 are attached to the rotation transmission ring 516 so as to face each other with the rotation transmission ring 516 interposed therebetween, and each focus key 534 is fitted to a notch 535 provided at the tip of the cam ring 511. Therefore, when an autofocus operation or a manual focus operation is performed and the rotation transmission ring 516 is rotated around the optical axis, the rotational force is transmitted to the cam ring 511 via the focus key 534. When the cam ring 511 is rotated about the optical axis, the rear group barrel 506 whose rotation is restricted by the cam roller 508 and the straight guide groove 507 is advanced and retracted along the cam groove 514 of the cam ring 511 by the cam roller 509. As a result, the focus lens 505 is driven and a focus operation is performed.

  In the present embodiment, an interchangeable lens barrel of a single-lens reflex camera has been described as an optical apparatus to which the vibration wave motor according to the present invention is applied. However, the optical apparatus to which the vibration wave motor according to the present invention is applied is not limited to this. For example, the vibration wave motor according to the present invention can be applied to an optical apparatus having a drive unit, regardless of the type of camera, such as a compact camera, an electronic still camera, and a portable information terminal with a camera.

  Next, an electronic apparatus according to the present invention will be described. The electronic apparatus according to the present invention corresponds to an electronic apparatus provided with a piezoelectric element as a drive source. For example, an electronic device incorporating a piezoelectric acoustic component such as a speaker, a buzzer, a microphone, and a surface acoustic wave (SAW) element corresponds to the electronic device according to the present invention. In addition, an electronic device including a driving source such as a liquid ejection device, a vibration device, a dust removing device, a movable mirror device, an ultrasonic oscillation device, a sensor device, and a shutter device also corresponds to the electronic device according to the present invention. FIG. 7 is an overall perspective view of a digital camera as an electronic apparatus according to the present invention when viewed from the front. The digital camera 700 includes a main body 701. On the front surface of the main body 701, an optical device 702 including a lens barrel, a microphone 703 (see a broken line), a strobe light emitting unit 704, and an auxiliary light unit 705 are arranged. A microphone hole 706 is formed in front of the microphone 703 for picking up sound from the outside. On the upper surface of the main body 701, a power button 707, a speaker 708, a zoom lever 709, and a release button 710 for performing a photographing operation are arranged. Since the speaker 708 is provided inside the main body 701, it is indicated by a broken line. In front of the speaker 708, a speaker hole 711 for transmitting sound to the outside is formed. In the digital camera 700, the piezoelectric element 200 and the piezoelectric element 300 described above are incorporated into piezoelectric acoustic components such as a microphone 703 and a speaker 708.

  In this embodiment, a digital camera has been described as the electronic apparatus according to the invention. However, the electronic device according to the present invention is not limited to this. For example, an electronic device having various piezoelectric acoustic components such as a voice reproducing device, a voice recording device, a mobile phone, and an information terminal, in which the piezoelectric element 200 and the piezoelectric element 300 are incorporated in the piezoelectric acoustic component is also an electronic device according to the present invention. Applicable.

  As described above, the piezoelectric element 200 and the piezoelectric element 300 are suitably used for vibration wave motors, optical devices, and electronic devices. For example, by incorporating the piezoelectric element 200 and the piezoelectric element 300, it is possible to provide a vibration wave motor that exhibits a driving force and durability equal to or higher than those of a conventional piezoelectric element containing lead. Further, by incorporating this vibration wave motor, it is possible to provide an optical device that exhibits durability and operational accuracy equivalent to or higher than that of a conventional lead-containing piezoelectric element. Furthermore, by using a piezoelectric acoustic component in which the piezoelectric element 200 and the piezoelectric element 300 are incorporated, an electronic device that exhibits a sound generation equivalent to or higher than that in the case of incorporating a conventional lead-containing piezoelectric element can be provided. The piezoelectric material according to the present invention can be incorporated not only in a vibration wave motor and an electronic device but also in devices such as an ultrasonic vibrator, a piezoelectric actuator, a piezoelectric sensor, and a ferroelectric memory.

  Next, the ultrasonic probe according to the present invention will be described. An ultrasonic probe according to the present invention includes the piezoelectric actuator described above, and has an ultrasonic oscillation function and a reflected wave reception function. As an example of the ultrasonic probe according to the present invention, FIG. 8A schematically shows an example of the configuration of the ultrasonic probe. However, the number, shape, and arrangement of the constituent members of the ultrasonic probe are not limited to the example of FIG. 8A. The ultrasonic probe 1001 includes a piezoelectric actuator 10011 and oscillates (transmits) ultrasonic waves generated due to the inverse piezoelectric effect of the piezoelectric actuator 10011 toward the subject. The wavy arrow in FIG. 8A schematically shows the propagation of the ultrasonic wave and is not a constituent member of the ultrasonic probe 1001. This ultrasonic wave is reflected by the internal tissue of the subject and returns toward the ultrasonic probe 1001 as an ultrasonic echo. Information corresponding to the internal structure of the subject can be obtained by the piezoelectric actuator 10011 converting the vibration caused by the ultrasonic echo into an electrical signal. The piezoelectric actuator 10011 responsible for the generation and reception of ultrasonic waves may not be a single one, and one of them may be substituted with a unit other than the piezoelectric actuator.

  Next, an ultrasonic inspection apparatus according to the present invention will be described. The ultrasonic inspection apparatus according to the present invention includes the ultrasonic probe of FIG. 8A, a signal processing unit, and an image generation unit. As an example of the ultrasonic inspection apparatus according to the present invention, FIG. 8B schematically shows an example of the configuration of the ultrasonic inspection apparatus. However, the connection order of the constituent units is not limited to the order shown in FIG. 8B. In the ultrasonic inspection apparatus illustrated in FIG. 8B, an electric signal caused by a reflected wave received by the ultrasonic probe 1001 is converted into data and stored in the signal processing unit 1002 and converted into image information in the image forming unit 1003. The ultrasonic inspection apparatus also has a function of transmitting this image information to an external image display unit (display).

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation and change are possible within the range of the summary.

Next, examples of the present invention will be specifically described, but the present invention is not limited to the following examples. First, Examples 1 to 5 and Comparative Examples 1 and 2 will be described. First, raw material powders of barium titanate, calcium titanate and calcium zirconate, which are all perovskite type metal oxides, were prepared by a solid phase method. Each raw material powder had an average particle size of 300 nm and a purity of 99.99% or more. Then, these raw material powders were mixed with manganese dioxide (MnO ₂ ) powder (purity 99.5% or more). At this time, the amounts of Ba, Ca, Ti, Zr, and Mn satisfy the composition of x = 0.14, y = 0.050, z = 0.002, and a = 0.9955 in the above formula (1). And weighed and mixed. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder.

  Next, the total weight of the mixed powder was set to 100 parts by weight, and 3 parts by weight of the PVA binder with respect to the mixed powder was adhered to the surface of the mixed powder using a spray dryer device to generate granulated powder. Thereafter, the produced granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to produce a disk-shaped molded body. A non-magnesium release agent was previously applied to the surface of the mold. Further, even when this molded body was further pressurized by a cold isostatic press molding machine, the resulting molded body was the same as the molded body that was not further pressurized.

  Next, using the electric furnace, the produced molded body was first heated to 600 ° C. in an air atmosphere and then heated to 1330 ° C., and the firing time shown in Table 1 of FIG. 9 was reached. The state of 1330 ° C. was maintained throughout. Thereafter, the temperature was lowered to room temperature by natural cooling. Thereby, disk-shaped ceramics (Examples 1 to 5 and Comparative Examples 1 and 2) were manufactured as piezoelectric materials.

  Next, the measured density of the piezoelectric material at room temperature (25 ° C.) was evaluated using the Archimedes method. Further, the relative density of the piezoelectric material was evaluated by using the theoretical density calculated from the lattice constant determined from the following X-ray diffraction and the weighed composition, and the actually measured density by the Archimedes method. The relative density obtained at this time is shown in Table 2 of FIG. The relative density of the piezoelectric material of Comparative Example 1 was as low as 90.8%, and the sintering was insufficient. Next, the disk-shaped ceramic was polished to a thickness of 0.5 mm, and the crystal structure was analyzed at an ambient temperature of 25 ° C. by X-ray diffraction on the polished surface. At this time, in any of the ceramics of Examples 1 to 5 and Comparative Examples 1 and 2, a peak corresponding to a tetragonal perovskite structure was observed.

Subsequently, the composition of each disk-shaped ceramic of Examples 1 to 5 and Comparative Examples 1 and 2 was evaluated by fluorescent X-ray analysis. As a result, in all the disk-shaped ceramics, the composition coincides with the composition at the time of weighing (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050 Mn _0.002 ) O ₃ . I understood that. Moreover, in all the disk shaped ceramics (Examples 1 to 5 and Comparative Examples 1 and 2), the Pb component contained was less than 1000 ppm.

Thereafter, each disk-shaped ceramic was polished so that the thickness of each disk-shaped ceramic was about 0.5 mm, and gold electrodes having a thickness of 400 nm were formed on both front and back surfaces by DC sputtering. In addition, 30 nm of titanium was formed as an adhesion layer between the electrode and the ceramic. This electrode-attached ceramic was cut to produce a 10 mm × 2.5 mm × 0.5 mm strip element. Further, as the first polarization treatment, each strip-like element is heated so that its surface becomes 100 ° C., and after applying a DC voltage to the gold electrode for 30 minutes so that an electric field of 1 kV / mm is generated in the ceramic, The strip-shaped element was naturally cooled so as to reach room temperature. After that, as the second polarization treatment, each strip-like element is heated so that the surface thereof becomes 75 ° C., so that an electric field of 500 V / mm opposite to the electric field of the first polarization treatment is generated in the ceramic. After applying a DC voltage to the gold electrode for 10 minutes, it was allowed to cool naturally. Thereby, the piezoelectric element (Examples 1-5) based on this invention and the piezoelectric element corresponding to the comparative examples 1 and 2 were produced. Next, as static characteristics of the piezoelectric element according to the present invention and the piezoelectric elements corresponding to Comparative Examples 1 and 2, d ₃₁ and Q _m of these strip-shaped piezoelectric elements at room temperature were measured by a resonance / anti-resonance method. In this measurement, an impedance analyzer (4294A manufactured by Agilent Technologies) was used. The measurement results at this time are shown in Table 2 of FIG. In the following tables, the absolute value of d ₃₁ at room temperature is represented as “| d _{31, RT} |”, and Q _m at room temperature is represented as “Q _{m, RT} ” in each table.

  Next, crystal grains and cross-sectional samples for domain observation were produced from the piezoelectric element according to the present invention and the piezoelectric elements corresponding to Comparative Examples 1 and 2. First, each electric element was mechanically polished with a polishing sheet in which abrasive grains were embedded, diamond slurry, or the like, and then subjected to chemical etching to prepare a mirror-like cross-sectional sample. Then, each cross-sectional sample was fixed to the SEM sample stage with a conductive paste, and a 3 nm carbon film was deposited on the cross-section.

  Subsequently, the cross section of each produced cross-sectional sample was observed with an SEM, and the average equivalent circle diameter of the crystal grains was calculated from the obtained photographic image. Specifically, for each cross-sectional sample, three photographic images with a magnification of 4000 times were obtained, and approximately 600 crystal grains were observed in each photographic image. This observed image was subjected to image processing to calculate an average equivalent circle diameter. The calculation results and measurement results at this time are shown in Table 2 of FIG. The calculation of the average equivalent circle diameter may be performed based on a photographic image of any cross section of the disk-shaped ceramic, the piezoelectric element before polarization, or the piezoelectric element after polarization.

  Moreover, the cross section of each produced cross-sectional sample was observed with SEM, and the width of the domain was measured from the obtained photographic image. A backscattered electron detector was used to detect the domain. Specifically, for each cross-sectional sample, five photographic images with a magnification of 4000 were obtained, and about 1000 crystal grains were observed in each photographic image to confirm the presence or absence of the first domain and the second domain. The measurement results at this time are shown in Table 2 of FIG.

Further, d ₃₁ and Q _m of the piezoelectric element according to the present invention and the piezoelectric elements corresponding to Comparative Examples 1 and 2 were measured at room temperature. The measurement results at this time are also shown in Table 2 of FIG.

As shown in Table 2, Comparative Example 1 includes both the crystal grain A having the first domain and the crystal grain B having the second domain, but the average equivalent circle diameter of the crystal grains is less than 1.0 μm. In addition, since the relative density was low and sintering was insufficient, Q _m (Q _{m, RT in} Table 2) at room temperature was as low as 470 and less than 600. Therefore, Comparative Example 1 is unsuitable for use as a drive source because of its large elastic loss during vibration. As shown in Table 2, Comparative Example 2 includes both crystal grains A having the first domain and crystal grains B having the second domain. However, in Comparative Example 2, the average equivalent circle diameter of the crystal grains is larger than 10 μm, the absolute value of d ₃₁ at room temperature (| d _{31, RT} | in Table 2) is less than 50 pm / V, and Q _m (Q _{m, RT in} Table 2) was also a low value of 510. Therefore, Comparative Example 2 is not suitable for use as a drive source because it does not easily expand and contract during vibration and has a large elastic loss during vibration. On the other hand, as shown in Table 2, in Examples 1 to 5, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, Examples 1 to 5 include both the crystal grain A having the first domain and the crystal grain B having the second domain, and the absolute value of d ₃₁ at room temperature is 70 pm / V or more. _m was 600 or more. Therefore, it was found that Examples 1 to 5 are suitable for use as a driving source because they easily expand and contract during vibration and have a small elastic loss during vibration.

  Next, Examples 6 to 10 will be described. In the same manner as in Examples 1 to 5, the raw material powder was weighed and then mixed to produce a mixed powder. Thereafter, the same process as in Examples 1 to 5 was performed except that the firing time for maintaining the temperature at 1340 ° C. by raising the temperature to 1340 ° C. was unified to 5.5 hours. 10).

Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. In addition, when the composition of all the disk-shaped ceramics was evaluated by fluorescent X-ray analysis, the composition was the composition at the time of weighing (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050). It was found to be consistent with Mn _0.002 ) O ₃ . Moreover, in all the disk-shaped ceramics (Examples 6 to 10), the Pb component contained was less than 1000 ppm. Thereafter, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, a first polarization process is performed on each strip-shaped element, and a second polarization process is performed on each strip-shaped element. To produce piezoelectric elements (Examples 6 to 10) according to the present invention. However, in the second polarization process at this time, the application time of the DC voltage was set to the application time S shown in Table 3 of FIG.

  Next, from the piezoelectric element (Examples 6 to 10) according to the present invention, a cross-sectional sample for observing crystal grains and domains was manufactured through the same steps as in Examples 1 to 5. Moreover, the average equivalent circle diameter of the crystal grains in each cross-sectional sample was calculated under the same conditions as in Examples 1 to 5. The calculation results at this time are shown in Table 3 of FIG. The average equivalent circle diameter may be calculated based on a photographic image of any cross section of the disk-shaped ceramic, the piezoelectric element before polarization, or the piezoelectric element after polarization, as in Examples 1 to 5.

Moreover, the cross section of each cross-sectional sample of the piezoelectric element (Examples 6 to 10) according to the present invention was observed with an SEM, and the width of the domain was measured from the obtained photographic image. At this time, a backscattered electron detector was used to detect the domain. Specifically, for each cross-sectional sample, 10 photographic images with a magnification of 4000 times were obtained, and approximately 2000 crystal grains were observed in each photographic image, and domains in the crystal grains were observed. The measurement results at this time are shown in Table 3 of FIG. Further, the obtained photographic image was subjected to image processing, and the number density (number%) of the crystal grains A having the first domain and the number density (number%) of the crystal grains B having the second domain were calculated. The calculation results at this time are shown in Table 3 of FIG. Further, d ₃₁ and Q _m of the piezoelectric element according to the present invention (Examples 6 to 10) were measured at room temperature. The measurement results at this time are also shown in Table 3 of FIG.

As shown in Table 3, in any of Examples 6 to 10, the average equivalent circle diameter of the crystal grains is 1.0 μm or more and 10 μm or less, and the crystal grains A and the second domains having the first domain Any of crystal grains B having a domain was included. Further, the absolute value of d ₃₁ at room temperature was 50 pm / V or more, and Q _m was 600 or more. In particular, in Examples 7 to 9 in which 5% by number or more of crystal grains B each having the first domain and the second domain exist, the absolute value of d ₃₁ at room temperature is 80 pm / V or more, Q _m was 800 or more. Therefore, it was found that Examples 7 to 9 have particularly preferable piezoelectric characteristics that they are easily expanded and contracted during vibration, and the elastic loss during vibration is smaller.

  Next, Examples 11 and 12 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1), where x = 0.14 and y = 0. 0.050, z = 0.002 and a = 0.9955 were weighed and mixed to satisfy the composition. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Thereafter, through the same steps as in Examples 6 to 10, a disk-shaped ceramic (common to Examples 11 and 12) was produced.

Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. In addition, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis, the composition was as measured (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050 Mn). It was found to be consistent with _{0.002) O 3.} Furthermore, in each disk-shaped ceramic (Examples 11 and 12), the Pb component contained was less than 1000 ppm.

Thereafter, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, a first polarization process is performed on each strip-shaped element, and a second polarization process is performed on each strip-shaped element. Thus, piezoelectric elements (Examples 11 and 12) according to the present invention were produced. However, in the piezoelectric element of Example 11, the DC voltage application time in the second polarization process is set to 13 minutes, and in the piezoelectric element of Example 12, the DC voltage application time in the second polarization process is 5 minutes. Was set to Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 4 of FIG.

Next, from the piezoelectric element (Examples 11 and 12) according to the present invention, cross-sectional samples for observing crystal grains and domains were prepared through the same steps as in Examples 1 to 5, and the average of the crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric element (Examples 11 and 12) according to the present invention has the number density (number%) of the crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 4 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric element according to the present invention (Examples 11 and 12) was 2.8 μm. At this time, in Example 12, crystal grains having both the first domain and the second domain were scattered as shown in FIG. On the other hand, in Example 11, the first domain and the second domain were present in different crystal grains, and no crystal grains having both the first domain and the second domain were confirmed. Table 4 can be seen a first domain value of it is d ₃₁ and Q _m of a piezoelectric material having a crystal grain in which the second domain coexist were both high.

In both Examples 11 and 12, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 4, in each of Examples 11 and 12, 5% by number or more of crystal grains A having the first domain and crystal grains B having the second domain are present at room temperature. The absolute value of d ₃₁ at 80 was 80 pm / V or more, and Q _m was 800 or more. Therefore, it was found that Examples 11 and 12 had particularly suitable piezoelectric characteristics that they were easily expanded and contracted during vibration and the elastic loss during vibration was smaller.

  Next, Examples 13 and 14 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1), where x = 0.14 and y = 0. 0.050, z = 0.002 and a = 0.9955 were weighed and mixed to satisfy the composition. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Thereafter, through the same steps as in Examples 6 to 10, a disk-shaped ceramic (common to Examples 13 and 14) was produced.

Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. In addition, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis, the composition was as measured (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050 Mn). It was found to be consistent with _{0.002) O 3.} Furthermore, in each disk-shaped ceramic (Examples 13 and 14), the Pb component contained was less than 1000 ppm.

Thereafter, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, a first polarization process is performed on each strip-shaped element, and a second polarization process is performed on each strip-shaped element. Thus, piezoelectric elements (Examples 13 and 14) according to the present invention were produced. However, in Example 13, the DC voltage application time in the first polarization process was set to 35 minutes, and the DC voltage application time in the second polarization process was set to 6 minutes. In Example 14, the DC voltage application time in the first polarization process was set to 60 minutes, and the DC voltage application time in the second polarization process was set to 7 minutes. Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 5 of FIG.

  Next, from the piezoelectric element (Examples 13 and 14) according to the present invention, through the same steps as in Examples 1 to 5, a cross-sectional sample for observing crystal grains and domains is prepared, and the average of crystal grains in each cross-sectional sample is prepared. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 13 and 14) according to the present invention have the number density (number%) of the crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 5 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 13 and 14) was 2.8 μm. At this time, in Example 14, as shown in FIG. 15, the presence of the first domain beyond the grain boundary of the adjacent crystal grains was observed. On the other hand, in Example 13, the first domain remained in one crystal grain, and the first domain beyond the grain boundary of the adjacent crystal grain was not confirmed.

In both Examples 13 and 14, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 5, in each of Examples 13 and 14, the crystal grains A having the first domain and the crystal grains B having the second domain are both present at 5% by number or more at room temperature. the absolute value of _{d 31} in is at 90 Pm/V above, _{Q m} was 900 or more. In particular, in Example 14 in which the first domain extending beyond the grain boundary between adjacent crystal grains extended, the Q _m at room temperature was 1100 or more. Therefore, it was found that Examples 13 and 14 had particularly preferable piezoelectric characteristics that they were easily expanded and contracted during vibration and the elastic loss during vibration was smaller.

  Next, Examples 15 to 20 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1), y = 0.050, z = 0. .002 and a = 0.9955 were weighed and mixed to satisfy the composition. At this time, in the above formula (1), the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that x had the composition shown in Table 6 of FIG. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder, and a disk-shaped molded body was produced through the same steps as in Examples 1-5. Thereafter, the produced molded body was first heated at 600 ° C. in an air atmosphere using an electric furnace, and then heated to the firing temperature shown in Table 6 of FIG. After holding for 5 hours, the temperature was lowered to room temperature by natural cooling. Thereby, disk-shaped ceramics (Examples 15 to 20) were manufactured as piezoelectric materials.

Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. By the way, when a molded body having the same composition as in Example 19 and Example 20 was fired at 1340 ° C., CaTiO _{3 as} an impurity phase was generated. Therefore, in Example 19, the firing temperature was set to 1370 ° C., and in Example 20, the firing temperature was set to 1400 ° C. Then, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, it was found that the composition of each disk-shaped ceramic coincided with the composition at the time of weighing. Moreover, in each disk-shaped ceramics (Examples 15 to 20), the Pb component contained was less than 1000 ppm.

  Thereafter, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, a first polarization process is performed on each strip-shaped element, and a second polarization process is performed on each strip-shaped element. Thus, piezoelectric elements (Examples 15 to 20) according to the present invention were produced. However, in the first polarization process, the application time of the DC voltage is set to 70 minutes, and in the second polarization process, the electric field of 600 V / mm opposite to the electric field of the first polarization process is generated in the ceramic. A DC voltage was applied to the electrode.

Then, the piezoelectric element according to the present invention (Example 15-20) were housed in a constant temperature bath (Espec Corp. SH-261), by changing the ambient temperature of the thermostatic bath, by the resonance-antiresonance _method, and _{d 31} It was measured Q _m. The temperature of the thermostatic bath was changed at 5 ° C./min, and was held for 5 minutes after the temperature was changed. Specifically, after each piezoelectric element was heated from 30 ° C. to 60 ° C., the temperature was lowered to −30 ° C., and then d ₃₁ and Q _m were measured. Furthermore, 10 ° C. and 40 ° C. of the absolute value of _{d 31} (hereinafter, respectively _{"| d 31,10 ℃ |", "| d 31, 40 ° C.} |". Be referred to as a) using a temperature dependence of the piezoelectric constant Piezoelectric constant change ratio | d31 _{, 40 ° C-} d31 _{, 10 ° C} | / | d31 _{, RT} | Here, “| d _{31, 40 ° C.} −d _{31, 10 ° C.} |” represents the difference in absolute value of d ₃₁ between 10 ° C. and 40 ° C. The measurement results and calculation results at this time are shown in Table 7 of FIG.

  Next, from the piezoelectric element according to the present invention (Examples 15 to 20), through the same steps as in Examples 1 to 5, a cross-sectional sample for observing crystal grains and domains was prepared, and the average of crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 15 to 20) according to the present invention have the number density (number%) of crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 7 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 15 to 20) was 2.8 μm.

In any of Examples 15 to 20, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 6, in any of Examples 15 to 20, the crystal grain A having the first domain and the crystal grain B having the second domain are both present at 5% by number or more at room temperature. The absolute value of d ₃₁ at 120 was 120 pm / V or more, and Q _m was 600 or more. Therefore, it was found that Examples 15 to 20 are suitable for use as a drive source because they easily expand and contract during vibration and have a small elastic loss during vibration. In particular, when the value of x is 0.02 or more and 0.10 or less, the absolute value of the _{d 31} under room temperature 150 pm / V or more, preferably from the viewpoint of expansion and contraction ease during vibration. Further, even when the value of x is 0.10 or more and 0.20 or less, the absolute value of d ₃₁ at room temperature is 130 pm / V or more, and the value of the piezoelectric constant change ratio is less than 0.30. It is preferable in that it is small and the ease of expansion and contraction during vibration hardly depends on temperature. Further, in any of Examples 15 to 20, since the value of x is smaller than 0.30 and the relative content of Ca is small, the firing temperature can be set to 1400 ° C. or less, and the production is performed. From the point of view of ease, it was found desirable.

  Next, Examples 21 to 25 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had an amount of Ba, Ca, Ti, Zr, and Mn in the above formula (1), where x = 0.13 and z = 0. .002 and a = 0.9955 were weighed and mixed to satisfy the composition. At this time, in the above formula (1), the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that y had the composition shown in Table 8 of FIG. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Then, the disk-shaped ceramics (Examples 21-25) were produced through the process similar to Examples 6-10.

  Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. Then, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, it was found that the composition of each disk-shaped ceramic coincided with the composition at the time of weighing. Moreover, in each disk shaped ceramic (Examples 21-25), the Pb component contained was less than 1000 ppm.

Next, in the same manner as in Examples 1 to 5, a strip-shaped element is prepared from each disk-shaped ceramic, and the first polarization treatment and the second polarization similar to those in Examples 15 to 20 are applied to each strip-shaped element. The piezoelectric element (Examples 21-25) based on this invention was produced by processing. Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 8 above.

Next, the piezoelectric elements (Examples 21 to 25) according to the present invention are accommodated in a thermostatic chamber (SH-261 manufactured by Espec Corp.), the atmospheric temperature of the thermostatic chamber is changed, and the dielectric of each piezoelectric element is performed by a parallel plate capacitor method. measuring the temperature dependence of the rate was determined Curie temperature T _C. At this time, an alternating electric field having a frequency of 1 kHz and an electric field strength of 10 V / cm was applied to each piezoelectric element. The temperature of the thermostatic chamber was changed from room temperature to 150 ° C. at a rate of 5 ° C./min, and held for 5 minutes after the temperature was changed. The measurement results and calculation results at this time are shown in Table 8 of FIG.

  Next, from the piezoelectric elements (Examples 21 to 25) according to the present invention, through the same steps as in Examples 1 to 5, a cross-sectional sample for observing crystal grains and domains was prepared, and the average of crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 21 to 25) according to the present invention have the number density (number%) of the crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 8 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 21 to 25) was 2.8 μm.

In any of Examples 21 to 25, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 8, in any of Examples 21 to 25, 5% by number or more of crystal grains A having the first domain and crystal grains B having the second domain are present at room temperature. the absolute value of _{d 31} in is at 110 pM / V or more was _{Q m} is also 800. Therefore, it was found that Examples 21 to 25 are suitable for use as a drive source because they easily expand and contract during vibration and the elastic loss during vibration is small. In particular, when the value of y is 0.010 or more and 0.095 or less, the absolute value of d ₃₁ at room temperature is 120 pm / V or more, and _TC is 100 ° C. or more. From the point of view, it is more desirable.

  Next, Examples 26 to 31 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1), where x = 0.14 and y = 0. .050 and a = 0.9955 were weighed and mixed to satisfy the composition. At this time, in the above formula (1), the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that z had the composition shown in Table 9 of FIG. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Then, the disk-shaped ceramics (Examples 26-31) were produced through the process similar to Examples 6-10.

  Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. Then, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, it was found that the composition of each disk-shaped ceramic coincided with the composition at the time of weighing. Moreover, in each disk-shaped ceramics (Examples 26 to 31), the Pb component contained was less than 1000 ppm.

Next, in the same manner as in Examples 1 to 5, a strip-shaped element is prepared from each disk-shaped ceramic, and the first polarization treatment and the second polarization similar to those in Examples 15 to 20 are applied to each strip-shaped element. The piezoelectric element (Examples 26-31) based on this invention was produced by processing. Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 9 of FIG.

  Next, from the piezoelectric element according to the present invention (Examples 26 to 31), through the same process as in Examples 1 to 5, a cross-sectional sample for observing crystal grains and domains was prepared, and the average of crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 26 to 31) according to the present invention have the number density (number%) of crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 9 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 26 to 31) was 2.8 μm.

In any of Examples 26 to 31, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 9, in any of Examples 26 to 31, there are 5% by number or more of crystal grains A having the first domain and crystal grains B having the second domain at room temperature. the absolute value of _{d 31} in is at 130pm / V or more was _{Q m} even 1000 or more. Therefore, it was found that Examples 26 to 31 are suitable for use as a driving source because they easily expand and contract during vibration and have a small elastic loss during vibration. In particular, if the value of z is 0.003 or more and 0.012 or less, since it is _{Q m} is 1200 or more at room temperature, more preferable from the viewpoint of elastic loss suppression.

Next, Examples 32-37 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had an amount of Ba, Ca, Ti, Zr, and Mn in the above formula (1), where x = 0.15 and y = 0. 0.060, z = 0.006 and a = 0.9955 were weighed and mixed so as to satisfy the composition. Here, regarding Examples 32 to 36, bismuth oxide (Bi ₂ O ₃ , purity 99.99% or more) was used as a raw material powder. Then, Bi was weighed and added so that the Bi content (mol) with respect to the sum of A (mol) and B (mol) in the above formula (1) was a value shown in Table 10 of FIG. Further, in order to adjust a in the above formula (1), appropriate amounts of barium carbonate and titanium oxide were added. These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Then, the disk-shaped ceramics (Examples 32-37) were produced through the process similar to Examples 6-10.

  Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. Then, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, it was found that the composition of each disk-shaped ceramic coincided with the composition at the time of weighing. Moreover, in each disk shaped ceramic (Examples 32-37), the Pb component contained was less than 1000 ppm.

Next, in the same manner as in Examples 1 to 5, a strip-shaped element is prepared from each disk-shaped ceramic, and the first polarization treatment and the second polarization similar to those in Examples 15 to 20 are applied to each strip-shaped element. The piezoelectric element (Examples 32-37) based on this invention was produced after processing. Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 10 of FIG.

Next, the piezoelectric elements according to the present invention (Examples 32 to 37) were accommodated in a thermostatic chamber (SH-261 manufactured by Espec Corp.), and the dielectric temperature of each piezoelectric element was changed by a parallel plate capacitor method by changing the atmospheric temperature of the thermostatic chamber. measuring the temperature dependence of the rate was determined Curie temperature T _C. At this time, an alternating electric field having a frequency of 1 kHz and an electric field strength of 10 V / cm was applied to each piezoelectric element. The temperature of the thermostatic chamber was changed from room temperature to 150 ° C. at a rate of 5 ° C./min, and held for 5 minutes after the temperature was changed. The measurement results and calculation results at this time are shown in Table 10 of FIG.

Next, the piezoelectric elements (Examples 32 to 37) according to the present invention are accommodated in a thermostatic chamber (SH-261 manufactured by Espec Corp.), and the atmospheric temperature of the thermostatic chamber is changed, and each piezoelectric element is subjected to a resonance / anti-resonance method. _{Q m} under the -30 ° C. were measured (hereinafter, _{"Q m, -30 ° C."} is expressed as.). Here, after changing the temperature of each piezoelectric element to −30 ° C., it was held for 5 minutes. The measurement results at this time are shown in Table 10 of FIG.

  Next, from the piezoelectric element according to the present invention (Examples 32-37), through the same steps as in Examples 1-5, crystal grains and cross-sectional samples for domain observation were prepared, and the average of crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 32-37) according to the present invention have the number density (number%) of crystal grains A having the first domains and the second domains, as in Examples 6-10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 10 of FIG. The calculated average equivalent circular diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 32-37) was 2.8 μm.

In any of Examples 32-37, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Further, as shown in Table 10, in any of Examples 32-37, 5% by number or more of crystal grains A having the first domain and crystal grains B having the second domain are present at room temperature. the absolute value of _{d 31} in is at 120 pm / V or more was _{Q m} 1,200 or more. Therefore, it was found that Examples 32 to 37 are suitable for use as a drive source because they easily expand and contract during vibration and the elastic loss during vibration is small. In particular, when Bi / (A + B) is 0.15 mol% or more and 0.41 mol% or less, since Q _m (Q _{m, −30 ° C.} ) under _{−30 ° C.} is 350 or more, the elastic loss at low temperature It was found that can be suppressed.

  Next, Examples 38 to 42 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and these raw material powders had an amount of Ba, Ca, Ti, Zr, and Mn in the above formula (1), x = 0.06, y = 0. 0.030 and z = 0.008 were weighed and mixed to satisfy the composition. Further, appropriate amounts of barium carbonate and titanium oxide were added so that a in the above formula (1) was a value shown in Table 11 of FIG. Thereafter, these mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder, and a disk-shaped molded body was produced through the same steps as in Examples 1-5. Thereafter, the produced compact was first heated at 600 ° C. in an air atmosphere using an electric furnace, and then heated to the firing temperature shown in Table 11 of FIG. After holding for 5 hours, the temperature was lowered to room temperature by natural cooling. Thereby, disk-shaped ceramics (Examples 38 to 42) were manufactured as piezoelectric materials.

  Next, the measured density of each disk-shaped ceramic at room temperature (25 ° C.) was evaluated using the Archimedes method. In addition, the relative density of each disk-shaped ceramic was evaluated using the theoretical density calculated from the lattice constant determined from the following X-ray diffraction and the weighed composition, and the measured density by the Archimedes method. The relative density obtained at this time is shown in Table 11 of FIG.

  Next, as in Examples 1 to 5, when the crystal structure of each disk-shaped ceramic was analyzed by X-ray diffraction at an ambient temperature of 25 ° C., only a peak corresponding to a tetragonal perovskite structure was observed. Then, when the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, it was found that the composition of each disk-shaped ceramic coincided with the composition at the time of weighing. Moreover, in each disk-shaped ceramics (Examples 38 to 42), the Pb component contained was less than 1000 ppm.

Thereafter, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, a first polarization process is performed on each strip-shaped element, and a second polarization process is performed on each strip-shaped element. Thus, piezoelectric elements (Examples 38 to 42) according to the present invention were produced. However, in the first polarization treatment, the application time of the DC voltage is set to 100 minutes, and in the second polarization treatment, the electric field of 650 V / mm opposite to the electric field of the first polarization treatment is generated in the ceramic. A DC voltage was applied to the electrode for 13 minutes. Thereafter, as in Examples 1 to 5, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature. The measurement results at this time are shown in Table 11 of FIG.

  Next, from the piezoelectric element according to the present invention (Examples 38 to 42), through the same process as in Examples 1 to 5, a cross-sectional sample for observing crystal grains and domains was prepared, and the average of crystal grains in each cross-sectional sample The equivalent circle diameter was calculated and the width of the domain was measured. At this time, the piezoelectric elements (Examples 38 to 42) according to the present invention have the number density (number%) of crystal grains A having the first domains and the second domains, as in Examples 6 to 10. The number density (number%) of crystal grains B was calculated. The calculation results and measurement results at this time are shown in Table 11 of FIG.

As shown in Table 11 of FIG. 21, in any of Examples 38 to 42, the average equivalent circle diameter of the crystal grains was 1.0 μm or more and 10 μm or less. In any of Examples 38 to 42, 5% by number or more of crystal grains A having the first domain and crystal grains B having the second domain are present, and the absolute value of d ₃₁ at room temperature is and at 80 Pm/V above was _{Q m} more than 600. Therefore, it was found that Examples 38 to 42 are suitable for use as a drive source because they easily expand and contract during vibration and have a small elastic loss during vibration. In particular, when a is 0.98 or more and 1.01 or less, the relative density is 95% or more, the firing temperature can be set to less than 1500 ° C., which is desirable from the viewpoint of ease of manufacture. I understood.

  Next, Example 43 will be described. As Example 43, the above-described vibration wave motor 400 was manufactured using the piezoelectric element of Example 2 described above. In the vibration wave motor 400, the rotation of the output shaft 403 in accordance with the application of the alternating voltage was confirmed. In addition, Example 44 will be described. As Example 44, the above-described interchangeable lens barrel 500 was manufactured using the vibration wave motor 400 of Example 43. In this interchangeable lens barrel 500, an autofocus operation according to application of an alternating voltage was confirmed.

Next, Example 45 will be described. First, a titanium compound, a calcium compound, a zircon compound, bismuth oxide (Bi ₂ O ₃ ), tetramanganese trioxide (Mn ₃ O ₄ ) were weighed and mixed so as to satisfy the composition of Example 34 in Table 10, A mixed powder was obtained. Thereafter, these mixed powders were mixed overnight using a ball mill to produce a mixed powder. Next, PVB was added to the produced mixed powder and mixed, and then the mixture was applied by the doctor blade method, resulting in a green sheet having a thickness of 50 μm. Furthermore, the conductive paste for internal electrodes was printed on this green sheet. Pd paste was used as the conductive paste. Thereafter, nine green sheets coated with a conductive paste were laminated to form a laminate, and the laminate was heated to 1340 ° C. and maintained at 1340 ° C. for 5 hours to produce a sintered body. did. Next, the sintered body is cut into a size of 10 mm × 2.5 mm, the side surfaces thereof are further polished, and a pair of external electrodes that alternately short-circuit the layers of the internal electrodes are further formed on the side surfaces. An upper electrode and a lower electrode connected to the electrodes were formed on the upper and lower surfaces by Au sputtering. Thereby, a piezoelectric element 300 having a laminated structure was produced. When the internal electrodes of the piezoelectric element 300 were observed, a plurality of layers of internal electrodes 302 made of Pd were formed alternately with the piezoelectric material layers 301. Thereafter, prior to the evaluation of piezoelectricity, the piezoelectric element 300 was subjected to polarization treatment. Specifically, as the first polarization process, the piezoelectric element 300 is heated to 100 ° C. in an oil bath, and a direct current voltage is applied for 70 minutes so that an electric field of 1 kV / mm is generated between the upper electrode 303 and the lower electrode 304. Then, the piezoelectric element 300 was naturally allowed to cool to room temperature. After that, as the second polarization treatment, the piezoelectric element 300 is heated to 75 ° C., and an electric field of 600 V / mm opposite to the electric field of the first polarization treatment is applied to the upper electrode 303 and the lower electrode 304. A DC voltage was applied for 10 minutes so as to occur in the meantime, followed by rapid cooling. When the piezoelectricity of the piezoelectric element 300 produced at this time was evaluated, it was confirmed that the piezoelectric element 300 had sufficient insulation and had good piezoelectric characteristics equivalent to the piezoelectric material of Example 1.

  Next, Example 46 will be described. As Example 46, the above-described vibration wave motor 407 was manufactured using the piezoelectric element 300 of Example 45. In the vibration wave motor 407, the rotation of the rotor 410 according to the application of the alternating voltage was confirmed. Embodiment 47 will be described. As Example 47, the above-described interchangeable lens barrel 500 was manufactured using the vibration wave motor 407 of Example 46. In this interchangeable lens barrel 500, an autofocus operation according to application of an alternating voltage was confirmed. Further, Example 48 will be described. As Example 48, the above-described digital camera 700 was manufactured using the piezoelectric element of Example 2. In this digital camera 700, the speaker operation according to the application of the alternating voltage was confirmed.

  Next, Example 49 will be described. As Example 49, the piezoelectric actuator 10011 described above was manufactured using the piezoelectric element 300 of Example 45. Further, an ultrasonic probe 1001 shown in FIG. 8A was produced using this piezoelectric actuator 10011. In the ultrasonic probe 1001, the transmission operation of the ultrasonic wave following the input electrical signal and the reception operation of the ultrasonic wave reflected from the subject were confirmed. Further, the ultrasonic inspection apparatus shown in FIG. 8B was manufactured using the ultrasonic probe 1001 described above. In this ultrasonic inspection apparatus, generation of an ultrasonic image with reduced noise was confirmed from the vibration data of the input and output ultrasonic waves.

  The piezoelectric material according to the present invention can exhibit good and stable piezoelectricity over a wide range of operating temperatures. Moreover, since it does not contain lead, the burden on the environment can be reduced. In addition, the piezoelectric material according to the present invention can be used without any problem for a vibration wave motor, and a device using a large amount of piezoelectric material such as an optical device and an electronic device including the vibration wave motor.

200, 300, 405, 412 Piezoelectric elements 201, 303 Upper electrode 202 Piezoelectric material portion 203, 304 Lower electrode 301 Piezoelectric material layer 302 Internal electrode 400, 407 Vibration wave motor 500 Interchangeable lens barrel 530 Vibration wave motor 700 Digital camera 703 Microphone 708 Speaker 1001 Ultrasonic probe 10011 Piezoelectric actuator 1002 Signal processing unit 1003 Image forming unit

Claims (13)

A piezoelectric material including a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, O, wherein the average equivalent circle diameter of the plurality of crystal grains is 1.0 μm or more and 10 μm or less,
The plurality of crystal grains include a crystal grain A having a first domain having a width of 300 nm to 800 nm and a crystal grain B having a second domain having a width of 20 nm to 50 nm. Piezoelectric material characterized by that.   5. The crystal grains A having the first domain in the plurality of crystal grains are present in an amount of 5% by number or more, and the crystal grains B having the second domain are in a number of 5% by number or more. Item 2. The piezoelectric material according to Item 1.   3. The piezoelectric material according to claim 1, wherein the crystal grain A includes a crystal grain A having both of the first domain and the second domain.   3. The piezoelectric material according to claim 1, wherein the crystal grain B includes a crystal grain B having both of the first domain and the second domain.   5. The piezoelectric material according to claim 1, wherein the first domain extends beyond a grain boundary between adjacent crystal grains. 6.   The piezoelectric material according to any one of claims 1 to 5, wherein the contained Pb component is less than 1000 ppm.   The ratio x of the number of moles of the contained Ca with respect to the sum of the number of moles of Ba and Ca contained is 0.02 ≦ x ≦ 0.30. The piezoelectric material according to any one of the above.   The ratio y of the number of moles of Zr contained relative to the sum of moles of Ti, Zr and Mn contained is 0.01 ≦ y ≦ 0.095. 8. The piezoelectric material according to any one of 7 above. Comprising an electrode and a piezoelectric material part,
The piezoelectric material which comprises the piezoelectric material which comprises the said piezoelectric material part is the piezoelectric material of any one of Claim 1 thru | or 8.   The piezoelectric element according to claim 9, wherein the piezoelectric material portions and electrodes are alternately stacked.   A vibration wave motor comprising: a vibrating body on which the piezoelectric element according to claim 9 is disposed; and a moving body.   An optical apparatus comprising a drive unit, wherein the drive unit includes the vibration wave motor according to claim 11.   An electronic apparatus comprising the piezoelectric element according to claim 9.