JP7150511B2 - Piezoelectric materials, piezoelectric elements, vibration wave motors, optical devices and electronic devices - Google Patents

Description

The present invention relates to a lead-free piezoelectric material, and a piezoelectric element, vibration wave motor, optical device, and electronic device using the piezoelectric material.

Lead-containing lead zirconate titanate is a representative piezoelectric material, and is used in various piezoelectric devices such as actuators, oscillators, sensors, and filters. However, if the lead component contained in discarded piezoelectric materials leaches into the soil, it may adversely affect the ecosystem. It is actively carried out.

By the way, in order to produce a piezoelectric device with a high vibration velocity, 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.

Barium calcium zirconate titanate (hereinafter referred to as “BCTZ”)-based non-lead piezoelectric material is one of the promising lead-free piezoelectric materials to replace lead zirconate titanate. Moreover, Patent Document 1 discloses a barium titanate-based material as a lead-free piezoelectric material having an excellent piezoelectric constant. This barium titanate-based material is {[(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 ]} composition. Here, M1, N1, M2, and N2 indicate additive elements. In this barium titanate-based material, the first end member (Ba _1-x1 M1 _x1 )((Ti _1-x Zr _x ) _1-y1 N1 _y1 )O ₃ has a rhombohedral crystal structure, and the second end member The component ((Ba _1-y Ca _y ) _1-x2 M2 _x2 )(Ti _1-y2 N2 _y2 )O ₃ has a tetragonal crystal structure. In the barium titanate-based material of Patent Document 1, two components with different crystal systems are used as a pseudo-binary solid solution, and the composition near the crystal phase boundary (morphotropic phase boundary, hereinafter referred to as "MPB") has a degree of freedom in the polarization direction. is used to improve the piezoelectric constant _d33 . For example, in Patent Document 1, the piezoelectric constant d33 of Ba( _Ti0.8Zr0.2 ) _{O3-50 %} ( _Ba0.7Ca0.3 ) _{TiO3 at 20} °C is 584 pC/N. is disclosed. Furthermore, in Patent Document 2, in order to improve the _Qm at room temperature of barium titanate as a piezoelectric material, part of the A site of barium titanate is replaced with Ca, and part of the B site is replaced with Mn, which is an acceptor. , Fe or Cu. Specifically, part of the B sites are replaced with acceptors to form oxygen vacancies, and the mobility of the ferroelectric domain wall is reduced (pinning), thereby improving _Qm .

JP 2009-215111 A JP 2010-120835 A

By the way, as shown in Patent Document 1, the increase in the degree of freedom in the direction of polarization of the composition near the MPB means that depolarization is easy. hereinafter referred to as “T _C ”) is a soft material having a temperature of less than 110°C. This means that the BCTZ-based lead-free piezoelectric material has a large elastic loss during resonance driving, so that the BCTZ-based lead-free piezoelectric material of Patent Document 1 cannot achieve a large _Qm . Further, in Patent Document 2, the formation of oxygen vacancies and the decrease in the mobility of the ferroelectric domain wall by substituting a portion of the B site with an acceptor improves the _Qm , but does not improve the piezoelectric constant. . That is, the barium titanate of Patent Document 2 cannot achieve a large piezoelectric constant. Therefore, there is no conventional lead-free piezoelectric material that achieves both a large piezoelectric constant and a large _Qm .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piezoelectric material that has a small 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 with excellent driving characteristics.

In order to achieve the above object, the piezoelectric material of the present invention includes a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O, wherein The plurality of crystal grains have a diameter of 1.0 μm or more and 10 μm or less, and the plurality of crystal grains include a crystal grain A having a first domain with a width of 300 nm or more and 800 nm or less, and a crystal grain A having a width of 20 nm or more and 50 nm or less. and a crystal grain B having two domains, and the piezoelectric material has a mechanical quality factor of 600 or more at room temperature .

In order to achieve the above object, a piezoelectric element of the present invention comprises a first electrode, a piezoelectric material portion and a second electrode, wherein the piezoelectric material constituting the piezoelectric material portion is the piezoelectric material of the present invention. Characterized by

In order to achieve the above object, a vibration wave motor of the present invention is characterized by comprising a vibrating body on which the piezoelectric element of the present invention is arranged, and a moving body that contacts the vibrating body.

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

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

According to the present invention, it is possible to provide a piezoelectric material that has a small environmental load and has both a large piezoelectric constant and a large mechanical quality factor. Further, according to the present invention, it is possible to provide piezoelectric elements, vibration wave motors, optical devices, and electronic devices that are excellent in driving characteristics.

FIG. 4 is a diagram schematically showing domains in each crystal grain appearing in the cross section of the piezoelectric material according to the present invention; 1 is a partial perspective view schematically showing the configuration of a piezoelectric element according to the present invention; FIG. 1 is a partial cross-sectional view schematically showing the configuration of a piezoelectric element according to the present invention; FIG. 1 is a diagram schematically showing the configuration of a vibration wave motor according to the present invention; FIG. FIG. 2 is a partially enlarged cross-sectional view showing the configuration of main parts of an interchangeable lens barrel of a single-lens reflex camera as an optical device according to the present invention; 1 is an exploded perspective view showing the configuration of an interchangeable lens barrel of a single-lens reflex camera as an optical device according to the present invention; FIG. 1 is an overall perspective view of a digital camera as an electronic device according to the present invention; FIG. 1 is a schematic diagram useful for explaining an ultrasonic probe according to an embodiment of the present invention; FIG. 1 is a schematic diagram useful for explaining an ultrasonic inspection apparatus according to an embodiment of the present invention; FIG. 1 is Table 1 showing firing times of Comparative Examples 1 and 2 and Examples 1-5. 4 is Table 2 showing calculation results and measurement results of Comparative Examples 1 and 2 and Examples 1 to 5. FIG. 3 is Table 3 showing calculation results and measurement results of Examples 6 to 10. FIG. 4 is Table 4 showing calculation results and measurement results of Examples 11 and 12. FIG. FIG. 4 is an enlarged cross-sectional view showing a grain having both a first domain and a second domain; 5 is Table 5 showing calculation results and measurement results of Examples 13 and 14. FIG. FIG. 4 is an enlarged cross-sectional view showing a first domain extending beyond the grain boundaries of adjacent grains; FIG. 6 is Table 6 showing calculation results and measurement results of Examples 15 to 20. FIG. 7 is Table 7 showing other calculation results and measurement results of Examples 15-20. FIG. 8 is Table 8 showing calculation results and measurement results of Examples 21 to 25. FIG. FIG. 9 is Table 9 showing calculation results and measurement results of Examples 26 to 31. FIG. FIG. 10 is Table 10 showing calculation results and measurement results of Examples 32 to 37. FIG. FIG. 11 is Table 11 showing calculation results and measurement results of Examples 38 to 42. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION 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 explained. A piezoelectric material according to the present invention is a piezoelectric material containing 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. Also, the piezoelectric material according to the present invention includes crystal grains A having a first domain with a width of 300 nm or more and 800 nm or less and crystal grains B having a second domain with a width of 20 nm or more and 50 nm or less. A piezoelectric material is an aggregate of crystal grains, and each crystal grain contains an element that constitutes the piezoelectric material. In the present invention, the main components of the piezoelectric material are preferably Ba, Ca, Ti, Zr, Mn and O. When the piezoelectric material is composed of Ba, Ca, Ti, Zr, Mn, and O as the main components, the six elements with the highest molar abundance ratios are Ba, Ca, Ti, Zr, Mn, O are meant to be occupied. Specifically, the piezoelectric material preferably contains 98.5 mol % or more of Ba, Ca, Ti, Zr, Mn, and O in total. Also, 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 represented by the chemical formula _ABO3 . In the perovskite-type metal oxide, the A element and the B element occupy specific positions of the unit cell called the A site and the B site as ions, respectively. For example, in a cubic unit cell, the A element is located at the vertices of the cube, and the B element is located at the center of the body. The O element occupies the face-center position of the cube as an anion of oxygen. When the unit lattice is distorted in the [001], [011] or [111] direction of the cubic unit lattice, it becomes a crystal lattice having a tetragonal, orthorhombic or rhombohedral perovskite structure, respectively.

Here, when a piezoelectric material including a plurality of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O is represented by a chemical formula of a perovskite-type metal oxide, it is represented by the following formula (1). (Ba _1-x Ca _x ) _a (Ti _1-yz Zr _y Mn _z )O ₃ (1)

In the above formula (1), x is the ratio of the content (mol) of Ca to A (mol), which is the sum of the contents of Ba and Ca, and y is the sum of the contents of Ti, Zr and Mn. It is the ratio of Zr content (mol) to B (mol). Further, in the above formula (1), z is the ratio of the content (mol) of Mn to B (mol), and a is the ratio (A/B) of A (mol) and B (mol) mol. The above formula (1) means a metal oxide in which the metal elements positioned at the A site are Ba and Ca, and the metal elements positioned at the B site are Ti, Zr and Mn. However, some 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 amounts of the elements (molar ratio) deviates somewhat, for example, within 1%, the metal oxide has a perovskite structure as a main phase, 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 from, for example, X-ray diffraction or electron diffraction applied to the piezoelectric material. As long as the perovskite structure is the main crystal phase (principal phase), the piezoelectric material is included in the piezoelectric material according to the present invention even if the piezoelectric material contains other crystal phases secondarily. In the present invention, the average equivalent circle diameter of crystal grains containing Ba, Ca, Ti, Zr, Mn, and O in 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 _Qm and mechanical strength. In the present invention, the equivalent circle diameter of a crystal grain means the "projected area equivalent circle diameter" generally referred to in the microscope observation method. It corresponds to the diameter of a perfect circle having an area equal to the projected area of the observed grain. In addition, the method for measuring the particle size is not particularly limited in the present invention. For example, the piezoelectric material is processed based on a sample preparation method such as Japanese Industrial Standards (hereinafter referred to as "JIS") R 1633, and the cross section of the obtained piezoelectric material is examined using a polarizing microscope, SEM, or the like. Observe based on JIS R 1670 or the like. After that, the obtained photographic image may be image-processed to determine the particle size. In addition, since the optimum magnification differs depending on the particle size of interest, 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 within the observation field, excluding the crystal grains protruding from the observation field. Although it is difficult to calculate the circle-equivalent diameter of all metal oxide crystal grains in the piezoelectric material, the observation field of view should be increased so that the particle size distribution in the piezoelectric material can be obtained correctly based on JIS Z 8827-1. Calculate the average circle equivalent diameter by adjusting the size, part, and number as appropriate.

By the way, when the average circle equivalent diameter is larger than 1.0 μm, the tetragonal strain of the crystal structure of the piezoelectric material is increased, so that the permittivity is increased and the piezoelectric constant is increased. In addition, when the average equivalent circle diameter is larger than 1.0 μm, the ratio of the internal loss caused by the crystal grain boundary and the boundary between domains (called domain wall, domain wall, or domain wall) becomes the dielectric loss tan δ. smaller in comparison. As a result, it is considered that Q _m becomes a size suitable for a piezoelectric material. In general, _Qm is a coefficient representing elastic loss due to vibration when evaluating a piezoelectric material as a vibrator, and the magnitude of _Qm is observed as the sharpness of a resonance curve in impedance measurement. That is, _Qm is a constant representing the sharpness of resonance of the vibrator. The higher the _Qm , the less energy is lost in vibration. When the insulating property and _Qm are improved, the long-term reliability of the piezoelectric element can be ensured when the piezoelectric material is used as a piezoelectric element and a voltage is applied to drive the piezoelectric element. Q _m can be measured according to EM-4501A, which is a standard of the Japan Electronics and Information Technology Industries Association. In general, a domain is also called a domain or a magnetic domain, and is a region in which the direction of spontaneous polarization is aligned and which is observed in a band shape (stripe shape) in a crystal grain by SEM or the like. In addition, the domain in this specification is synonymous with what is called a domain structure or a domain assembly. Generally, in piezoelectric materials, the reciprocal of Q _m (Q _m ⁻¹ ) represents the internal loss, and the internal loss is said to be proportional to the dielectric loss (tan δ). The internal loss of a ferroelectric material is represented by 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 equation (2), Q _{m (SD)} ⁻¹ is the intrinsic internal loss of one domain, and Q _{m (Ce)} ⁻¹ is due to the structure of the ferroelectric material (grain boundaries, domain walls) is the internal loss. Also, tan δ _(SD) is the intrinsic dielectric loss of one domain, k is the electromechanical coupling coefficient of one domain, and C is a constant.

Generally, in the above equation (2), both Q _m(SD) ⁻¹ and Q _m(Ce) ⁻¹ are so small that they can be ignored, and the dielectric loss (tan δ) of the ferroelectric material is equal to tan δ _(SD) . Since it is proportional, it is explained that Q _m ⁻¹ is proportional to tan δ. However, when the average equivalent circle diameter of crystal grains is smaller than 1.0 μm, Q _m(Ce) ⁻¹ becomes too large to be ignored, and 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, the density is improved, and the mechanical strength of the piezoelectric material is increased. The density of the piezoelectric material can be measured, for example, by the Archimedes method. Here, the ratio of the measured density (ρ calc. ) 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. If so, it is considered to be sufficiently densified as a piezoelectric material.

In addition, the piezoelectric material according to the present invention includes crystal grains A having a first domain with a width of 300 nm or more and 800 nm or less and crystal grains B having a second domain with a width of 20 nm or more and 50 nm or less. include. The first domain and the second domain may both exist in the same crystal grain in the piezoelectric material, or each 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 stripes, and the width of the domains present in the piezoelectric material according to the present invention (hereinafter simply referred to as "domains of the present invention") corresponds to the length of the short sides of these stripes. . The width of the domain can be measured in the photographic image obtained by observing the cross section of the piezoelectric material produced based on the sample preparation method such as JIS R 1633 by SEM. In order to observe the domain of the present invention with an SEM, it is preferable to mirror-polish the cross section of the piezoelectric material and deposit a thin conductive film on the cross section. A secondary electron detector or a backscattered electron detector is used as the SEM detector used for domain observation in the present invention.

Generally, there is a trade-off relationship between _Qm and the piezoelectric constant, and it is known that the larger the _Qm , the smaller the piezoelectric constant, and conversely, the smaller the _Qm , the larger the piezoelectric constant. On the other hand, in the present invention, by adjusting the width of the domain in each crystal grain contained in the piezoelectric material, the trade-off relationship between _Qm and the piezoelectric constant is eliminated, and a large piezoelectric constant (especially, a large piezoelectric constant To provide a piezoelectric material that achieves both the absolute value of _d31 ) and a large _Qm . Specifically, the piezoelectric material according to the present invention includes a crystal grain A having a first domain that contributes to an increase in Q _m and an increase in the absolute value of the piezoelectric constant d ₃₁ (hereinafter simply referred to as “d ₃₁ ”). At the same time, it contains grains B having a second domain that contributes to . Since the domain inversion occurs relatively easily in the second domain, the crystal grain B having the second domain enters between the crystal grains A having the first domain, thereby causing stress and stress between the crystal grains. It is believed that distortion is reduced. This increases the absolute value of _d31 in the piezoelectric material according to the invention.

Here, 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, the case where the width of the second domain is 50 nm or less will be considered. . In this case, the density of the domain walls of the 90° domains with high electric field responsiveness increases. As a result, it is believed that the piezoelectric material has an increased dielectric constant and a larger absolute value of _d31 . 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 residual polarization is increased. As a result, the absolute value of _d31 is considered to be a suitable value for piezoelectric materials. Therefore, in the present invention, the width of the second domain is set to 20 nm or more and 50 nm or less. In general, d ₃₁ of the piezoelectric material is determined based on the Japan Electronics and Information Technology Industries Association standard (JEITA EM-4501A) from the measurement results of the resonance frequency and anti-resonance frequency obtained using a commercially available impedance analyzer, similar to Q _m . , can be calculated. This method of calculating _d31 is hereinafter referred to as the resonance/anti-resonance method. Note that if the absolute value of _d31 is less than 50 pm/V, it is necessary to supply a large amount of power to the piezoelectric device when driving the piezoelectric device including the piezoelectric material. Therefore, the absolute value of _d31 is preferably 50 pm/V or more for the piezoelectric material, and in particular, when the absolute value of _d31 is 80 pm/V or more, the power consumption during driving of the piezoelectric device can be suppressed, and the piezoelectric material can be practically used. Suitable. Furthermore, when the absolute value of _d31 is 90 pm/V or more, the piezoelectric device has better performance.

Also, a case where the width of the first domain is 800 nm or less in crystal grains 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 will be considered. In this case, it is considered that Q _m increases as the residual stress generated between crystal grains due to domain switching of non-180 degree domains decreases. Next, consider the case where the width of the first domain is 300 nm or more. In this case, _Qm is considered to increase because the internal loss caused by grain boundaries and domain walls decreases. Therefore, in the present invention, the width of the first domain is set to 300 nm or more and 800 nm or less. By the way, if the value of _Qm is smaller than 600, power consumption will increase when the piezoelectric material is used as a piezoelectric element and driven as a resonant device. Therefore, regarding the value of _Qm of the piezoelectric material according to the present invention, it is preferable that the value of _Qm is 600 or more. In particular, when the value of _Qm is 800 or more, an extreme increase in power consumption does not occur, which is more preferable. Furthermore, when the value of _Qm is 1000 or more, it can have good performance as a piezoelectric element.

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

As described above, if the width of the domain is 300 nm or more and 800 nm or less, _Qm is considered to be large, and if the width of the domain is 20 nm or more and 50 nm or less, the absolute value of _d31 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, 5% by number or more of the crystal grains A having the first domain are present, and the second domain is It is set so that the crystal grains B having 5 number % or more are present. As a result, in the piezoelectric material, it is possible to increase the number of crystal grains that contribute to an increase in _Qm and _at the same time increase the number of crystal grains that contribute to an increase in the _absolute value of _d31 . A suitable piezoelectric material having an absolute value of 80 pm/V or more can be obtained. In particular, the crystal grains B having the second domain are 10% by number or more and 50% by number or less of the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O. is more preferable because the absolute value of _d31 of is larger. Further, the crystal grains A having the first domain are 10% by number or more and 50% by number or less of the crystal grains containing Ba, Ca, Ti, Zr, Mn, and O, the piezoelectric material according to the present invention. is more preferable because the Q _m of is larger. When 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 observe more crystal grains to improve the counting accuracy. Specifically, the domain width is measured in at least 200, particularly 1000 or more crystal grains, and the number of crystal grains A having the first domain and crystal grains B having the second domain is counted. is desirable.

Also, consider the case where the first domain and the second domain are included in the same crystal grain. In this case, the increase in _Qm and the increase in the absolute value of _d31 are effectively generated in synergy. Therefore, in the present invention, it is more preferable that the piezoelectric material contains 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, _Qm is 900 or more and the absolute value of d31 is 85 _pm/V or more. It is more preferable as a material. A crystal grain having both the first domain and the second domain means that one crystal grain has one domain with a width of 300 nm or more and 800 nm or less and one domain with a width of 20 nm or more and 50 nm or less. means that there are more than one 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 piezoelectric material has a first domain extending beyond the grain boundaries of adjacent grains. In this case, the domain switching of the non-180 degree domain causes less residual stress between crystal grains, and the internal loss caused by the grain boundaries becomes less. As a result, the effect of increasing _Qm becomes greater. Therefore, in the present invention, it is more preferable that the first domain of the piezoelectric material extends beyond the grain boundaries of adjacent crystal grains. That the first domain extends beyond the grain boundary of the crystal grain means that the domain with a width of 300 nm or more and 800 nm or less extends two times beyond the grain boundary while maintaining the same domain width. It means that there is something in the field of view that extends to more than one grain. At this time, the domains exist in two or more grains with the same direction of dielectric polarization. Also, consider the case where the Pb component contained in the piezoelectric material is less than 1000 ppm. In this case, even if a piezoelectric material or an element or device using a piezoelectric material is discarded and exposed to acid rain or left in a harsh environment, the lead component in the piezoelectric material may adversely affect the environment. can be reduced. Therefore, it is preferable that the Pb component contained in the piezoelectric material according to the present invention is less than 1000 ppm.

Next, the composition ratio of the piezoelectric material according to the present invention will be explained. First, the case of containing Ca is considered. In this case, the phase transition temperature (T _to ) from the tetragonal system to the orthorhombic system when the temperature is decreased and the phase transition temperature (T _ot ) from the orthorhombic system to the tetragonal system when the temperature is increased are decreased. In particular, when the value of x, which is the ratio of the content (mol) of Ca to A (mol), which is the sum of the contents of Ba and Ca, is 0.02 or more and 0.10 or less, T _to and T _ot is close to room temperature. It also exhibits a large absolute value of _d31 (eg, 150 pm/V or more) near room temperature (eg, 0° C. to 40° C.). When the value of x is larger than 0.10, T _to and T _ot decrease below 0° C., and the temperature dependence of the piezoelectric constant becomes small. On the other hand, when x is less than 0.30, solid solution of Ca is promoted and the firing temperature can be lowered. Therefore, in the present invention, it is more preferable that the value of x in the above formula (1) is 0.02≦x≦0.30.

By the way, the piezoelectric material according to the present invention undergoes successive phase transitions to rhombohedral, orthorhombic, tetragonal and cubic as the temperature rises from a low temperature. A phase transition in the present embodiment exclusively refers to a phase transition from orthorhombic to tetragonal or from tetragonal to orthorhombic. The phase transition temperature can be evaluated by a measurement method similar to T _C described later, and in the present embodiment, the temperature at which the value obtained by differentiating the dielectric constant with respect to the sample temperature is the maximum is defined as the phase transition temperature. The crystal system can be evaluated by X-ray diffraction, electron diffraction, Raman scattering, or the like. In the vicinity of 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 exhibits a maximum value or 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 becomes small. Therefore, it is more preferable from the viewpoint of controlling the device. However, as described above, the piezoelectric constant exhibits a maximum value near the phase transition temperature. Therefore, by controlling the relationship between the phase transition temperature and the operating temperature range through the composition of the piezoelectric material, both the controllability of the device and the large piezoelectric constant can be achieved. It is desirable to From this point of view, x is preferably 0.20 or less because the piezoelectric constant is high and the temperature dependence of the piezoelectric performance is suppressed.

In this embodiment, the temperature dependence of _d31 and _Qm of the piezoelectric element measured using the resonance/antiresonance method may be measured as follows. Specifically, the piezoelectric element is placed in a constant temperature bath, and _d31 and _Qm are measured by the resonance/antiresonance method while changing the temperature of the atmosphere. The temperature change rate is not particularly limited, but may be changed at 1 to 10° C./min. After changing the temperature, holding the temperature constant until the temperature of the piezoelectric element follows the ambient temperature, and then measuring the piezoelectric constant and the electromechanical quality factor using the resonance/anti-resonance method, the reproducibility of the measurement results is improved. It is desirable to measure in this way because it will be higher. The time for keeping the temperature constant is not particularly limited, but it is desirable to be 1 to 10 minutes.

Also, the case of containing Zr is considered. In this case, the temperature of T _to and T _ot rises. In particular, by setting the value of y, which is the molar ratio of Zr to the sum of the number of moles of Ti, Zr, and Mn in the above formula (1), to 0.01 or more, T _to and T _ot are close to room temperature, and the operation The piezoelectric constant in the temperature range (eg -30°C to 60°C) is increased. As a result, it is possible to reduce the power required to drive piezoelectric elements using piezoelectric materials, piezoelectric elements having a laminated structure, vibration wave motors, optical devices, electronic devices, and the like. On the other hand, by setting y to 0.095 or less, T _C reaches a high temperature of, for example, 100° C. or higher, and depolarization is further suppressed when used at high temperatures. is wider, and deterioration of the piezoelectric constant with time becomes smaller. Therefore, in the present invention, it is more preferable that the value of y in the above formula (1) is 0.01≤y≤0.095. T _C is the temperature above which the piezoelectric material loses its piezoelectricity. In the present embodiment, T _C is the temperature at which the dielectric constant is maximized near the phase transition temperature between the ferroelectric phase (tetragonal phase) and the paraelectric phase (cubic phase). The dielectric constant is measured by applying an AC electric field with a frequency of 1 kHz and an electric field strength of 10 V/cm, for example, using an impedance analyzer, according to the parallel plate capacitor method.

Next, in the piezoelectric material according to the present invention, the case where T _C is 100° C. or higher will be considered. In this case, even under the harsh conditions of 80° C. expected in a car in summer, the piezoelectricity can be maintained without loss, and a stable piezoelectric constant and _Qm can be obtained. Therefore, in the present invention, it is more preferable that T _C is 100° C. or higher. Also, let us consider z, which is the molar ratio of Mn to the sum of the molar numbers of Ti, Zr and Mn in the above formula (1). Mn has the property of varying in valence between 2 and 4, and plays a role in compensating for charge balance defects in the piezoelectric material. When the value of z is 0.003 or more, the concentration of oxygen vacancies in the crystal lattice of the piezoelectric material increases, and the residual stress generated between crystal grains due to domain switching of non-180 degree _domains decreases. It is thought that the value of 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, when the value of z is in the range of 0.003≤z≤0.012, the value of _Qm is 1200 or more, which is more preferable. Therefore, in the present invention, it is more preferable that the value of z in the above formula (1) is 0.003≤z≤0.012. Here, Mn is not limited to metal Mn, and may be contained in the piezoelectric material as a Mn component, and the form of inclusion is not limited. For example, it may be dissolved in the B site, or may be included in the grain boundary. Alternatively, the piezoelectric material may contain the Mn component in the form of metal, ion, oxide, metal salt, complex, or the like. In addition, from the viewpoint of insulation and sinterability, the presence of Mn is preferable. The valence of Mn can generally be 4+, 2+, or 3+, but if the valence of Mn is lower than 4+, Mn becomes an acceptor. When Mn exists as an acceptor in a perovskite structure crystal, oxygen vacancies are formed in the crystal. Oxygen vacancies can improve the _Qm of piezoelectric materials when they form defect dipoles. Therefore, in the present invention, the valence of Mn is preferably lower than 4+. In order for Mn to exist with a valence lower than 4+, it is preferable to have a trivalent element on the A site. A preferable trivalent element at this time is Bi. Here, the valence of Mn can be evaluated by measuring the temperature dependence of magnetic susceptibility.

In the present invention, it is more preferable for the piezoelectric material to contain an auxiliary component made of Bi, because this improves the _Qm at low temperatures. In particular, in the above formula (1), when the content (mol) of Bi with respect to the sum of A (mol) and B (mol) is 0.15% or more and 0.40% or less, the low temperature region, for example, - _Qm at 30° C. becomes as large as 350 or more, for example. This facilitates control in a low-temperature region in a piezoelectric device using a piezoelectric material. In the present invention, more preferably, in the above formula (1), the value of a, which indicates the ratio of A (mol) to B (mol), is 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. below °C.

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 it may be in any form such as ceramics, powder, single crystal, thin film, slurry, granulated powder, compact, etc. Ceramics is preferred. In the present embodiment, the term “ceramics” refers to an aggregate (bulk body) of crystal particles whose basic component is a metal oxide and which is sintered (sintered) by heat treatment, that is, a so-called polycrystal. Ceramics processed after sintering are also included.

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

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

In the present embodiment, the raw material for adjusting a, which indicates 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 in the piezoelectric material, is particularly Not limited. The effect of adjusting a is the same for any of Ba compounds, Ca compounds, Ti compounds, Zr compounds, and Mn compounds.

Next, the steps for obtaining granules for molding will be described. The method of granulating the raw material powder of the piezoelectric material according to the present invention to obtain molding granules is not particularly limited. Examples of binders that can be used for granulation 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, more preferably 2 to 5 parts by weight from the viewpoint of increasing the density of the molded article. The raw material powder may be granulated from a mixed powder obtained by mechanically mixing a Ba compound, a Ca compound, a Ti compound, a Zr compound and a Mn compound, or the raw material powder may be obtained after calcining these compounds at about 800 to 1300 ° C. may be granulated. Alternatively, after calcining the Ba compound, Ca compound, Ti compound, and Zr compound, the Mn compound may be added together with the binder. The most preferable granulation method is the spray drying method from the viewpoint that the particle size of the granular granulated powder for molding can be made more uniform.

Next, a process for obtaining a molded body will be described. The method for producing the compact of piezoelectric material according to the present invention is not particularly limited. A compact is a solid made from raw material powder, granulated powder, or slurry. As means for producing a molded body, uniaxial pressure processing, cold isostatic processing, warm isostatic processing, cast molding, extrusion molding, and the like can be used.

Next, the process of obtaining the piezoelectric material will be described. In the present invention, the piezoelectric material is obtained by sintering, but the method of sintering the piezoelectric material is not particularly limited. Examples of the sintering method include sintering in an electric furnace, sintering in a gas furnace, electric heating method, microwave sintering method, millimeter wave sintering method, HIP (hot isostatic pressing), and the like. A sintering furnace used for sintering with an electric furnace or gas may be a continuous furnace or a batch furnace. Also, 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 crystals grow sufficiently. In particular, the preferred sintering temperature is 1200°C or higher and 1500°C or lower, and the more preferred sintering temperature is 1250°C or higher and 1450°C or lower. The 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 keep the sintering temperature constant within the above range and carry out the sintering treatment for 2 hours or more and 24 hours or less. At this time, a sintering method such as a two-stage sintering method may be used, but considering productivity, a method that does not cause abrupt temperature changes is preferable.

Next, a thin film made of a 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 desirably 400 nm or more and 10 μm or less, more preferably 500 nm or more and 3 μm or less. This is because by setting the film thickness of the piezoelectric material to 400 nm or more and 10 μm or less, a sufficient electromechanical conversion function as a piezoelectric element can be obtained. Here, the method for forming the thin film made of the 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), etc. Since the chemical solution deposition method or the sputtering method can easily increase the film formation area, the chemical solution deposition method or the sputtering method is the most preferable lamination method. Also, the substrate used for the piezoelectric material according to the present invention is preferably a single crystal substrate cut and polished along the (001) plane or (110) plane. By using a single-crystal substrate cut and polished along a specific crystal plane, the thin film of piezoelectric material provided on the surface of the substrate can be strongly oriented in the same direction.

Next, a piezoelectric element according to the present invention will be explained. 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 forming the piezoelectric material portion 202 . By using the piezoelectric material according to the present invention as a piezoelectric material forming 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 with a thickness of about 5 nm to 10 μm. The material of this conductive layer is not particularly limited, and any material commonly used in piezoelectric elements may be used. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, 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 made of a laminate of two or more of these. Also, the upper electrode 201 and the lower electrode 203 may be made of different materials. The method of manufacturing the upper electrode 201 and the lower electrode 203 is not limited, and they may be formed by baking a metal paste, sputtering, vapor deposition, or the like. Further, both the upper electrode 201 and the lower electrode 203 may be patterned into desired shapes and used.

Next, the polarization of the piezoelectric element according to the present invention will be explained. In a piezoelectric element, if the polarization axes are aligned in a certain direction, the piezoelectric constant of the piezoelectric element increases. In a piezoelectric material or a piezoelectric element, it is possible to confirm that the polarization axes are aligned in a certain direction by confirming the presence of residual polarization in PE (polarization-electric field) hysteresis measurement. The method of polarizing 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. Also, the polarization may be performed in the atmosphere or in silicone oil. The temperature for polarization is preferably about room temperature (for example, 25°C) to 150°C. However, the distribution of the width of domains existing in the piezoelectric material before polarization and the pinning effect of the domain walls due to oxygen vacancies generated by the addition of Mn differ depending on the composition and manufacturing method of the piezoelectric material constituting the piezoelectric element. , the optimum conditions for polarization are also different. In particular, the higher the polarization temperature and the longer the polarization time, the larger the domain width. For example, if the width of most of the domains of the piezoelectric material before poling already matches the width of the second domain, then as the polarization temperature increases and the poling time increases during poling the domain width also increases, The number of second domains is reduced. In particular, when the polarization temperature is too high or the polarization time is too long, the domain width becomes too large, and the second domain may disappear. On the other hand, when the polarization temperature is low or the polarization time is short, domain growth is suppressed, so even if the second domain remains sufficiently, the first domain may hardly be formed.

In polarization, when only the polarization time and the polarization temperature are used as parameters, the domain width basically increases according to the polarization time and the polarization temperature. It becomes difficult to control the grains B to coexist. Therefore, it is preferable to control the polarization using parameters other than the polarization time and the polarization temperature. For example, as the first polarization treatment, a first domain is generated by applying a DC voltage to the piezoelectric element at a temperature around _TC , and then the piezoelectric element is once cooled to stabilize the first domain. . Then, as the subsequent second polarization treatment, 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 treatment to generate a second domain. can be considered. 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 voltage lower than this. For example, the electric field applied in the second poling treatment is appropriately adjusted together with the poling time, poling temperature, etc. so that the second domains have a desired distribution and number. As another polarization, for example, a relatively small DC voltage (eg, 650 V/mm) is applied to the piezoelectric element at a temperature slightly lower than _TC (eg, about 10° C.) as a first polarization treatment. to generate the first domain. Then, as the subsequent second polarization treatment, a weak DC voltage or pulse voltage is applied in the opposite direction to the first polarization treatment while cooling at a constant rate to generate a second domain. Conceivable.

Next, the insulating properties of the piezoelectric material according to the present invention will be explained. 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. Also, 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 up to 500 V/cm is applied to the piezoelectric material under driving conditions of the piezoelectric element. Further, when the resistivity is 1 GΩcm or more, a sufficient polarization effect can be obtained. Tan δ and resistivity can be measured by using an impedance analyzer, for example, by applying an AC electric field with a frequency of 1 kHz and an electric field strength of 10 V/cm to the piezoelectric element.

Next, the insulating properties of the piezoelectric element according to the present invention will be explained. FIG. 3 is a partial cross-sectional view schematically showing the configuration of the piezoelectric element according to the present invention. In FIG. 3, the 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 laminated. The piezoelectric material layer 301 is made of the above piezoelectric material. As the electrode layers, in addition to at least one layer of the internal electrode 302, each layer of the upper electrode 303 and the lower electrode 304 is provided. For example, the piezoelectric element 300 may be a laminated structure in which two piezoelectric material layers 301 and one internal electrode 302 are alternately laminated (FIG. 3A). An upper electrode 303 and a lower electrode 304 are arranged on the upper surface and the lower surface of this laminated structure, respectively. The number of layers of the piezoelectric material layers 301 and internal electrodes 302 provided in the piezoelectric element 300 is not limited to the example shown in FIG. 3A, and is not particularly limited. For example, the piezoelectric element 300 may be a laminated structure in which nine piezoelectric material layers 301 and eight internal electrodes 302 are alternately laminated (FIG. 3B). An upper electrode 303 and a lower electrode 304 are also arranged on the upper and lower surfaces of this laminated structure, respectively. 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. The size and shape of the internal electrode 302, the upper electrode 303, the lower electrode 304, and the external electrodes 305 and 306 do not necessarily have to be the same as the size and shape of the piezoelectric material layer 301, and each electrode is divided into a plurality of parts. 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 with a thickness of about 5 nm to 10 μm. The material of each electrode is not particularly limited as long as it is commonly used for piezoelectric elements. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, Cu, and compounds thereof can be used. In particular, the internal electrode 302 and the external electrodes 305 and 306 may consist of one of these materials, or may be a mixture of two or more or an alloy of two or more. Also, the internal electrode 302 and the external electrodes 305 and 306 may be formed by stacking two or more of these materials. Also, the electrodes 302-306 may be made of different materials.

In the piezoelectric element 300, in particular, the internal electrode 302 contains Ag and Pd, and the weight ratio M1/M2 between the Ag content M1 and the Pd content M2 is 0.25≦M1/M2≦4.0. is preferred, and 0.3≦M1/M2≦3.0 is more preferred. If the weight ratio M1/M2 is less than 0.25, the sintering temperature of the internal electrodes becomes high, which is undesirable. On the other hand, if the weight ratio M1/M2 is greater than 4.0, the internal electrodes are insular and non-uniformly present within the plane, which is undesirable. Moreover, in order to make the electrode material inexpensive, it is preferable that the internal electrode 302 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, each layer of the internal electrode 302 may be short-circuited to match the phase of the drive voltage. For example, half of the layers of the internal electrode 302 and the upper electrode 303 may be shorted by the external electrode 305 , and the other half of the layers of the internal electrode 302 and the lower electrode 304 may be shorted by the external electrode 306 . Furthermore, each layer 2 of the internal electrode 30 short-circuited with the upper electrode 303 and each layer of the internal electrode 302 short-circuited with the lower electrode 304 may be alternately arranged. Note that the form of short-circuiting each electrode is not limited to the form shown in FIG. Electrodes and wiring for short-circuiting may be provided on the side surface of the laminated structure, or a through hole may be provided to penetrate each piezoelectric material layer 301, and a conductive material may be provided inside the through hole to short-circuit the electrodes. good too.

Next, a 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 force of a pressure spring. and an output shaft 403 provided integrally with the rotor 402 (FIG. 4(A)). The vibrator 401 has 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 (an epoxy-based or cyanoacrylate-based adhesive). be. The piezoelectric element 405 has, for example, a single-layer structure (only one piezoelectric material layer exists) 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 a piezoelectric material, the piezoelectric material expands and contracts due to the transverse piezoelectric effect. Here, when an elastic body such as a metal is bonded to the piezoelectric element, the elastic body is bent by expansion and contraction of the piezoelectric material, and bending traveling waves are generated in the elastic body. The vibration wave motor 400 is driven using this bending traveling wave. Specifically, when two-phase alternating voltages whose phases are different from each other by odd multiples of π/2 are applied to the piezoelectric element 405 , bending traveling waves are generated in the vibrator 401 , and the vibration on the sliding surface of the vibrator 401 is increased. Each point of performs an elliptical motion. When the rotor 402 is pressed against the sliding surface of the vibrator 401, the rotor 402 receives frictional force from the vibrator 401 and rotates in the opposite direction to the bending traveling wave. In vibration wave motor 400 , output shaft 403 is joined to a driven body (not shown), so the driven body is driven by output shaft 403 by the rotational force of 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 pressurizes and contacts the vibrator 408 by a pressure spring 409 (FIG. 4B). )). The vibrator 408 has a metal elastic body 411 composed of divided cylindrical bodies, and a piezoelectric element 412 sandwiched between the cylindrical bodies of the metal elastic body 411 . The piezoelectric element 412 has a laminated structure (in which a plurality of piezoelectric material layers are present), for example, like the piezoelectric element 300 described above, and an upper electrode and a lower electrode are arranged outside 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 with a bolt, holds and fixes the piezoelectric element 412 , and constitutes the vibrator 408 . By applying two-phase alternating voltages having mutually 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 vibrator 408 . In the vibration wave motor 407, a constricted circumferential groove 413 is formed in the upper portion of the vibrator 408 to increase the displacement of the circular vibration. Since the rotor 410 is in pressure contact with the vibrator 408 , it obtains frictional force for driving from the vibrator 408 . The rotor 410 is rotatably supported by bearings (not shown).

Next, optical instruments according to the present invention will be described. FIG. 5 is a partially enlarged cross-sectional view showing the configuration of the main parts 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 the configuration of an interchangeable lens barrel of a single-lens reflex camera as an optical device according to the present invention. 5 and 6, an interchangeable lens barrel 500 includes a fixed barrel 501, a rectilinear guide barrel 502, and a front group barrel 503 as fixed members, and these fixed members are fixed to a detachable mount 504 of the camera. be done. The interchangeable lens barrel 500 also 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 is formed in the rectilinear guide tube 502 in the optical axis direction. Cam rollers 508 and 509 protruding radially outward 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 circumference of the rectilinear guide tube 502 . A roller 512 fixed to the cam ring 511 is fitted in the circumferential groove 513 of the rectilinear guide cylinder 502, so that the rectilinear guide cylinder 502 and the cam ring 511 are restricted from moving relative to each other in the optical axis direction, and integrated in the optical axis direction. to move. A cam groove 514 for the focus lens 505 is formed in the cam ring 511 , and the cam roller 509 described above is fitted in the cam groove 514 . A rotation transmission ring 516 rotatably held at a fixed position with respect to the fixed cylinder 501 by a ball race 515 is arranged on the outer peripheral side of the fixed cylinder 501 . The rotation transmission ring 516 has shafts 517 extending radially, and rollers 518 are rotatably held on each shaft 517 . The large-diameter portion 519 of the roller 518 contacts the mount-side end surface 521 of the manual focus ring 520 (FIG. 5B). Also, the small-diameter portion 522 of the roller 518 contacts the joining member 523 . In the interchangeable lens barrel 500, six rollers 518 are arranged at regular intervals along the outer periphery of a rotation transmission ring 516 and are rotatably held on each shaft 517. As shown in FIG.

A low-friction sheet 524 is arranged on the inner diameter of the manual focus ring 520 and sandwiched between the mount-side end face 525 of the fixed barrel 501 and the front-side 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 radially fitted with the inner diameter 527 of the manual focus ring 520 . Further, the inner diameter 527 of the manual focus ring 520 is radially fitted with the outer diameter portion 528 of the fixed barrel 501 . The low-friction sheet 524 reduces friction when the manual focus ring 520 rotates relative to the fixed barrel 501 around the optical axis. The large-diameter portion 519 of the roller 518 and the mount-side end face 521 of the manual focus ring 520 contact each other due to the force of the wave washer 529 pressing the vibration wave motor 530 forward of the lens. The vibration wave motor 530 of the interchangeable lens barrel 500 constitutes a driving section of the interchangeable lens barrel 500 and has a structure similar to that of the vibration wave motor 400, for example. In addition, due to the force of the wave washer 529 pressing the vibration wave motor 530 forward of the lens, the small diameter portion 522 of the roller 518 and the joining member 523 are brought into contact with each other while applying an appropriate pressure. The wave washer 529 is restricted from moving in the mounting direction by a washer 531 bayonet-coupled to the fixed cylinder 501 . A spring force (biasing force) generated by the wave washer 529 is transmitted to the vibration wave motor 530 and further to the roller 518 to press the manual focus ring 520 against the mount-side end face 525 of the fixed barrel 501 . That is, the manual focus ring 520 is assembled into the interchangeable lens barrel 500 while being pressed against the mount-side end surface 525 of the fixed barrel 501 via the low-friction sheet 524 . Therefore, when the vibration wave motor 530 rotates with respect to the fixed cylinder 501 , the joining member 523 frictionally contacts the small diameter portion 522 of the roller 518 , so that the roller 518 rotates about the shaft 517 . As a result, the rotary transmission ring 516 rotates around the optical axis (autofocus operation). Also, consider a case where a manual operation input unit (not shown) applies a rotational force around the optical axis to the manual focus ring 520 . In this case, since the mount-side end surface 521 of the manual focus ring 520 is pressed against the large-diameter portion 519 of the roller 518, the roller 518 rotates around the shaft 517 due to frictional force. This also causes the rotary transmission ring 516 to rotate around the optical axis. At this time, the rotation of vibration wave motor 530 is suppressed by the frictional holding force between rotor 532 and 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. 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 around the optical axis, the rear lens group barrel 506 whose rotation is restricted by the cam roller 508 and the rectilinear guide groove 507 advances and retreats 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 this embodiment, the interchangeable lens barrel of a single-lens reflex camera has been described as an optical device to which the vibration wave motor according to the present invention is applied. However, the optical equipment 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 optical equipment having a drive unit regardless of the type of camera, such as a compact camera, an electronic still camera, and a mobile information terminal with a camera.

Next, electronic equipment according to the present invention will be described. An electronic device having a piezoelectric element as a drive source corresponds to the electronic device according to the present invention. For example, electronic devices incorporating piezoelectric acoustic components such as speakers, buzzers, microphones, and surface acoustic wave (SAW) elements correspond to electronic devices according to the present invention. In addition, an electronic device having a drive source such as a liquid ejection device, a vibrating device, a dust removing device, a movable mirror device, an ultrasonic oscillator, a sensor device, a shutter device, etc., 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 device according to the present invention when viewed from the front. A digital camera 700 has a main body 701, and an optical device 702 including a lens barrel, a microphone 703 (see broken line), a strobe light emitting section 704, and an auxiliary light section 705 are arranged on the front surface of the main body 701. FIG. A microphone hole 706 is formed in front of the microphone 703 to pick up sounds from the outside. A power button 707 , a speaker 708 , a zoom lever 709 , and a release button 710 for executing a photographing operation are arranged on the upper surface of the main body 701 . Since the speaker 708 is provided inside the main body 701, it is indicated by a dashed line. A speaker hole 711 is formed in front of the speaker 708 for transmitting sound to the outside. In the digital camera 700, the piezoelectric element 200 and the piezoelectric element 300 described above are incorporated into piezoelectric acoustic components such as the microphone 703 and the speaker 708. FIG.

Note that in this embodiment, a digital camera has been described as an electronic device according to the present 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, and having the piezoelectric element 200 or the piezoelectric element 300 incorporated in the piezoelectric acoustic component is also included in the 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 driving force and durability equal to or greater than those in the case of incorporating a conventional lead-containing piezoelectric element. In addition, by incorporating this vibration wave motor, it is possible to provide an optical device exhibiting durability and operating accuracy equal to or greater than those in the case of incorporating a conventional lead-containing piezoelectric element. Furthermore, by using a piezoelectric acoustic component in which the piezoelectric element 200 or the piezoelectric element 300 is incorporated, it is possible to provide an electronic device that exhibits sound generation performance equal to or greater than that in the case of incorporating a conventional lead-containing piezoelectric element. The piezoelectric material according to the present invention can be incorporated not only in vibration wave motors, electronic devices, etc., but also in devices such as ultrasonic transducers, piezoelectric actuators, piezoelectric sensors, and ferroelectric memories.

Next, an 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 wave oscillating function and a reflected wave receiving function. As an example of the ultrasonic probe according to the present invention, FIG. 8A shows a schematic diagram of an example of the configuration of the ultrasonic probe. However, the number, shape, and arrangement of constituent members of the ultrasonic probe are not limited to the example in FIG. 8A. The ultrasonic probe 1001 includes a piezoelectric actuator 10011, and oscillates (transmits) ultrasonic waves toward the subject due to the inverse piezoelectric effect of the piezoelectric actuator 10011. FIG. A wavy arrow in FIG. 8A schematically shows the propagation of ultrasonic waves 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. The piezoelectric actuator 10011 converts the vibration caused by the ultrasonic echo into an electrical signal, thereby obtaining information corresponding to the internal structure of the subject. The piezoelectric actuator 10011 responsible for oscillating and receiving ultrasonic waves may not be a single one, and one of them may be replaced by a unit other than the piezoelectric actuator.

Next, an ultrasonic inspection apparatus according to the present invention will be described. An 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 an ultrasonic inspection apparatus according to the present invention, FIG. 8B shows a schematic diagram of an example of the configuration of an ultrasonic inspection apparatus. However, the connection order of each component unit is not limited to the order shown in FIG. 8B. In the ultrasonic inspection apparatus shown in FIG. 8B, the signal processing unit 1002 converts and stores electrical signals resulting from reflected waves received by the ultrasonic probe 1001, and the image forming unit 1003 converts the data into image information. The ultrasonic inspection apparatus also has a function of transmitting this image information to an external image display unit (display).

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist thereof.

EXAMPLES Next, examples of the present invention will be specifically described, but the present invention is not limited by 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, all of which are perovskite metal oxides, were produced by a solid phase method. All raw material powders had an average particle size of 300 nm and a purity of 99.99% or more. These raw material powders were then mixed with manganese dioxide (MnO ₂ ) powder (purity of 99.5% or higher). 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) Weighed and mixed. Appropriate amounts of barium carbonate and titanium oxide were added to adjust a in the above formula (1). 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 100 parts by weight, and a PVA binder of 3 parts by weight with respect to the mixed powder was adhered to the surface of the mixed powder using a spray dryer to produce 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 compact. The surface of the mold was previously coated with a non-magnesium release agent. Further, even if this molded article was further pressurized by a cold isostatic press molding machine, the resulting molded article was the same as the molded article that was not further pressurized.

Next, using an electric furnace, the formed body was first heated while being held at 600° C. in an air atmosphere, then further heated to 1330° C., and fired for the time shown in Table 1 of FIG. A state of 1330° C. was maintained throughout. After that, the temperature was lowered to room temperature by natural cooling. As a result, disk-shaped ceramics (Examples 1 to 5 and Comparative Examples 1 and 2) were produced as piezoelectric materials.

Next, the measured density of the piezoelectric material at room temperature (25° C.) was evaluated using the Archimedes method. Also, the relative density of the piezoelectric material was evaluated using the theoretical density calculated from the lattice constant obtained from the following X-ray diffraction and the weighed composition, and the measured density by the Archimedes method. The relative densities obtained at this time are 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 by X-ray diffraction of the polished surface at an atmospheric temperature of 25°C. At this time, in all of the ceramics of Examples 1 to 5 and Comparative Examples 1 and 2, a peak corresponding to a tetragonal perovskite structure was observed.

Next, 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 disk-shaped ceramics, the composition _matches the composition at the time of weighing ( _Ba0.86Ca0.14 ) _{0.9955 ( Ti0.948Zr0.050Mn0.002} ) _{O3 .} I found out. In addition, the Pb component contained in all disc-shaped ceramics (Examples 1 to 5 and Comparative Examples 1 and 2) was less than 1000 ppm.

After that, each disk-shaped ceramic was polished so that the thickness of each disk-shaped ceramic was about 0.5 mm, and a gold electrode having a thickness of 400 nm was formed on both the front and back surfaces by a DC sputtering method. A titanium film of 30 nm was formed as an adhesion layer between the electrode and the ceramics. This electrode-attached ceramic was cut to produce strip-shaped elements of 10 mm×2.5 mm×0.5 mm. Furthermore, as a first polarization treatment, each strip-shaped element was heated so that its surface reached 100° C., and a DC voltage was applied to the gold electrodes for 30 minutes so that an electric field of 1 kV/mm was generated in the ceramics. The strip-shaped element was allowed to cool naturally to room temperature. After that, as the second polarization treatment, each strip-shaped element was heated so that its surface reached 75° C., and an electric field of 500 V/mm was generated in the ceramics in the opposite direction to the electric field of the first polarization treatment. After applying a DC voltage to the gold electrode for 10 minutes, it was allowed to cool naturally. Thus, piezoelectric elements according to the present invention (Examples 1 to 5) and piezoelectric elements corresponding to Comparative Examples 1 and 2 were produced. Next, as the 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 were measured at room temperature by the 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 each table below, the absolute value of d ₃₁ at room temperature is expressed as “|d _31,RT |”, and Q _m at room temperature is expressed as “Q _m,RT ” in each table.

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

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

In addition, the cross section of each cross-sectional sample thus prepared was observed with an SEM, and the width of the domain was measured from the obtained photographic image. A backscattered electron detector was used to detect the domains. Specifically, five photographic images at a magnification of 4000 were obtained for each cross-sectional sample, and approximately 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.

Furthermore, 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 the 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 not suitable for use as a drive source because of its large elastic loss during vibration. As shown in Table 2, Comparative Example 2 includes both the crystal grain A having the first domain and the crystal grain B having the second domain. However, in Comparative Example 2, the average equivalent circle diameter of the crystal grains was larger than 10 μm, the absolute value of d ₃₁ at room temperature (|d _31,RT | in Table 2) was 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 is difficult to expand and contract when vibrating and has a large elastic loss when vibrating. On the other hand, as shown in Table 2, in Examples 1 to 5, the average circle equivalent diameter of the crystal grains was 1.0 μm or more and 10 μm or less. Furthermore, Examples 1 to 5 include both the crystal grain A having the first domain and the crystal grain B having the second domain, the absolute value of _d31 at room temperature is 70 pm / V or more, and Q _m was also 600 or more. Therefore, it was found that Examples 1 to 5 are suitable for use as a drive source because they easily expand and contract when vibrating and have small elastic loss when vibrating.

Next, Examples 6 to 10 will be described. As in Examples 1 to 5, raw material powders were weighed and mixed to form a mixed powder. After that, the same process as in Examples 1 to 5 was performed except that the firing time for heating to 1340 ° C. and maintaining the state at 1340 ° C. was unified to 5.5 hours. 10) was produced.

Then, in the same manner 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 disc-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 Mn _0.002 )O ₃ . In addition, the Pb component contained in all disc-shaped ceramics (Examples 6 to 10) was less than 1000 ppm. After that, in the same manner as in Examples 1 to 5, strip-shaped elements were produced from each disk-shaped ceramic, each strip-shaped element was subjected to the first polarization treatment, and each strip-shaped element was further subjected to the second polarization treatment. Thus, piezoelectric elements according to the present invention (Examples 6 to 10) were produced. However, in the second polarization treatment at this time, the DC voltage application time was set to the application time S shown in Table 3 of FIG.

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

Further, the cross section of each cross section sample of the piezoelectric element (Examples 6 to 10) according to the present invention was observed by SEM, and the width of the domain was measured from the obtained photographic image. Also in this case, a backscattered electron detector was used to detect the domains. Specifically, 10 photographic images at a magnification of 4000 were obtained for each cross-sectional sample, and approximately 2000 crystal grains were observed in each photographic image to observe domains within the crystal grains. 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 (% by number) of crystal grains A having the first domain and the number density (% by number) of 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 elements (Examples 6 to 10) according to the present invention 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 grain A having the first domain and the second domain Any of the grains B with domains were included. In addition, the absolute value of _d31 at room temperature was 50 pm/V or more, and the _Qm was also 600 or more. In particular, in Examples 7 to 9 in which 5% by number or more of the crystal grains B having the first domain and the second domain are present, the absolute value of _d31 at room temperature is 80 pm/V or more, _Qm was 800 or more. Therefore, it was found that Examples 7 to 9 easily expand and contract when vibrating, and have particularly favorable piezoelectric characteristics such as smaller elastic loss when vibrating.

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

Then, in the same manner 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 the composition at the time of weighing (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050 Mn _0.002 ) _O3 . Furthermore, the Pb component contained in each disk-shaped ceramic (Examples 11 and 12) was less than 1000 ppm.

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

Next, from the piezoelectric element according to the present invention (Examples 11 and 12), through the same steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric element according to the present invention (Examples 11 and 12), as in Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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 circle diameters of the crystal grains of the piezoelectric elements according to the present invention (Examples 11 and 12) were both 2.8 μm. At this time, in Example 12, as shown in FIG. 13, crystal grains having both the first domain and the second domain were observed here and there. On the other hand, in Example 11, the first domain and the second domain existed in different crystal grains, and no crystal grain having both the first domain and the second domain was confirmed. As can be seen from Table 4, the piezoelectric material having crystal grains in which the first domain and the second domain coexist had higher d ₃₁ and Q _m values.

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 both Examples 11 and 12, the crystal grains A having the first domain and the crystal grains B having the second domain were both present at 5% by number or more, and at room temperature The absolute value of _d31 was 80 pm/V or more, and _Qm was 800 or more. Therefore, it was found that Examples 11 and 12 easily expanded and contracted during vibration, and had particularly favorable piezoelectric characteristics such that elastic loss during vibration was small.

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

Then, in the same manner 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 the composition at the time of weighing (Ba _0.86 Ca _0.14 ) _0.9955 (Ti _0.948 Zr _0.050 Mn _0.002 ) _O3 . Furthermore, the Pb component contained in each disk-shaped ceramic (Examples 13 and 14) was less than 1000 ppm.

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

Next, from the piezoelectric element according to the present invention (Examples 13 and 14), through the same steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric element according to the present invention (Examples 13 and 14), as in Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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. In addition, the calculated average equivalent circle diameters of the crystal grains of the piezoelectric elements according to the present invention (Examples 13 and 14) were both 2.8 μm. At this time, in Example 14, as shown in FIG. 15, the existence of the first domains beyond the grain boundaries of adjacent crystal grains was found here and there. On the other hand, in Example 13, the first domain remained within one crystal grain, and the first domain beyond the grain boundary between adjacent crystal grains 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 both Examples 13 and 14, the crystal grains A having the first domain and the crystal grains B having the second domain were present at 5% by number or more, and at room temperature The absolute value of _d31 was 90 pm/V or more, and _Qm was 900 or more. In particular, in Example 14, in which the first domain extends beyond the grain boundaries of adjacent crystal grains, _Qm at room temperature was 1100 or more. Therefore, it was found that Examples 13 and 14 easily expanded and contracted during vibration and had particularly favorable piezoelectric characteristics such that elastic loss during vibration was small.

Next, Examples 15 to 20 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1) were y = 0.050, z = 0. Weighed and mixed to meet the composition of 0.002 and a=0.9955. At this time, the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that x in the above formula (1) had the composition shown in Table 6 of FIG. Appropriate amounts of barium carbonate and titanium oxide were added to adjust a in the above formula (1). 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 to 5. After that, using an electric furnace, the formed body was first held at 600 ° C. in an air atmosphere and heated, and then heated to the firing temperature shown in Table 6 in FIG. After holding for 0.5 hours, the temperature was lowered to room temperature by natural cooling. As a result, disc-shaped ceramics (Examples 15 to 20) were produced as piezoelectric materials.

Then, in the same manner 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 the compacts having the same composition as in Examples 19 and 20 were 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. After that, the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, and it was found that the composition of each disk-shaped ceramic matched the composition at the time of weighing. Further, the Pb component contained in each disk-shaped ceramic (Examples 15 to 20) was less than 1000 ppm.

After that, in the same manner as in Examples 1 to 5, strip-shaped elements were produced from each disk-shaped ceramic, each strip-shaped element was subjected to the first polarization treatment, and each strip-shaped element was further subjected to the second polarization treatment. Thus, piezoelectric elements according to the present invention (Examples 15 to 20) were produced. However, in the first polarization treatment, the application time of the DC voltage was set to 70 minutes, and in the second polarization treatment, gold was applied so that an electric field of 600 V/mm in the opposite direction to the electric field in the first polarization treatment was generated in the ceramics. A DC voltage was applied to the electrodes.

Next, the piezoelectric elements according to the present invention (Examples 15 to 20) were housed in a constant temperature bath (SH-261 manufactured by Espec Co., Ltd.), and the atmospheric temperature of the constant temperature bath was changed to determine d ₃₁ and d 31 by the resonance/antiresonance method. Q _m measurements were made. The temperature of the constant temperature bath was changed at a rate of 5° C./min, and the temperature was maintained for 5 minutes after changing the temperature. Specifically, after raising the temperature of each piezoelectric element from 30° C. to 60° C. and then lowering the temperature to −30° C., d ₃₁ and Q _m were measured. Furthermore, using the absolute values of d31 at 10°C and 40°C (hereinafter referred to as “| _d31,10 ° _C |” and “| _d31,40°C |” respectively), the temperature dependence of the piezoelectric constant A piezoelectric constant change ratio |d 31,40 _{° C.} −d 31,10 _{° C.} |/|d _{31, RT} | as a measure of the temperature was calculated. Here, "|d31,40 _{°C -d31,10 °C} |" represents the difference in the absolute values of d31 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, cross-sectional samples for observing crystal grains and domains were produced, and the average number of crystal grains in each cross-sectional sample was The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric element according to the present invention (Examples 15 to 20), similarly to Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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. In addition, the calculated average equivalent circle 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 grains A having the first domain and the crystal grains B having the second domain were both present at 5% by number or more, and at room temperature The absolute value of _d31 was 120 pm/V or more, and _Qm 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 when vibrating and have small elastic loss when vibrating. In particular, when the value of x is 0.02 or more and 0.10 or less, the absolute value of _d31 at room temperature is 150 pm/V or more, which is preferable from the viewpoint of ease of expansion and contraction during vibration. Further, even if the value of x is 0.10 or more and 0.20 or less, the absolute value of _d31 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 easiness of expansion and contraction during vibration does not easily depend on temperature. Furthermore, in any of Examples 15 to 20, since the value of x is less than 0.30 and the relative content of Ca is small, the firing temperature can be set to 1400 ° C. or less. It was found to be desirable from the viewpoint of ease of

Next, Examples 21 to 25 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1) were x = 0.13, z = 0. Weighed and mixed to meet the composition of 0.002 and a=0.9955. At this time, the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that y in the above formula (1) had the composition shown in Table 8 of FIG. Appropriate amounts of barium carbonate and titanium oxide were added to adjust a in the above formula (1). These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. Thereafter, disc-shaped ceramics (Examples 21 to 25) were produced through the same steps as in Examples 6 to 10.

Then, in the same manner 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. After that, the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, and it was found that the composition of each disk-shaped ceramic matched the composition at the time of weighing. Moreover, the Pb component contained in each of the disk-shaped ceramics (Examples 21 to 25) was less than 1000 ppm.

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

Next, the piezoelectric elements according to the present invention (Examples 21 to 25) were housed in a constant temperature bath (SH-261 manufactured by Espec Co., Ltd.), the ambient temperature of the constant temperature bath was changed, and the dielectric of each piezoelectric element was measured by the parallel plate capacitor method. The temperature dependence of the modulus was measured and the Curie temperature _TC was determined. At this time, an AC electric field with a frequency of 1 kHz and an electric field strength of 10 V/cm was applied to each piezoelectric element. The temperature of the constant temperature bath was changed from room temperature to 150° C. at a rate of 5° C./min, and the temperature was maintained for 5 minutes after changing the temperature. The measurement results and calculation results at this time are shown in Table 8 of FIG.

Next, from the piezoelectric element according to the present invention (Examples 21 to 25), through the same steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric elements according to the present invention (Examples 21 to 25), similarly to Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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. In addition, the calculated average equivalent circle diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 21 to 25) was all 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, the crystal grains A having the first domain and the crystal grains B having the second domain were both present at 5% by number or more, and at room temperature The absolute value of _d31 was 110 pm/V or more, and the _Qm was also 800 or more. 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 have small elastic loss during vibration. In particular, when the value of y is 0.010 or more and 0.095 or less, the absolute value of _d31 at room temperature is 120 pm/V or more, and T _C is 100° C. or more. is more desirable from the viewpoint of

Next, Examples 26 to 31 will be described. First, the same raw material powders as in Examples 1 to 5 were used, and the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1) were x = 0.14, y = 0. Weighed and mixed to meet the composition of 0.050 and a=0.9955. At this time, the amounts of Ba, Ca, Ti, Zr, and Mn were adjusted so that z in the above formula (1) had the composition shown in Table 9 of FIG. Appropriate amounts of barium carbonate and titanium oxide were added to adjust a in the above formula (1). These mixed powders were mixed by dry mixing for 24 hours using a ball mill to produce a mixed powder. After that, through the same steps as in Examples 6 to 10, disk-shaped ceramics (Examples 26 to 31) were produced.

Then, in the same manner 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. After that, the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, and it was found that the composition of each disk-shaped ceramic matched the composition at the time of weighing. In addition, the Pb component contained in each disk-shaped ceramic (Examples 26 to 31) was less than 1000 ppm.

Next, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, and each strip-shaped element is subjected to the first polarization treatment and the second polarization as in Examples 15 to 20. After processing, piezoelectric elements according to the present invention (Examples 26 to 31) were produced. Thereafter, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature in the same manner as in Examples 1-5. 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 steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric elements according to the present invention (Examples 26 to 31), similarly to Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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. In addition, the calculated average equivalent circle 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, the crystal grains A having the first domain and the crystal grains B having the second domain were both present at 5% by number or more, and at room temperature The absolute value of _d31 was 130 pm/V or more, and the _Qm was also 1000 or more. Therefore, it was found that Examples 26 to 31 are suitable for use as a drive source because they easily expand and contract when vibrated and have small elastic loss when vibrated. In particular, when the value of z is 0.003 or more and 0.012 or less, _Qm at room temperature is 1200 or more, which is more desirable from the viewpoint of suppressing elastic loss.

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

Then, in the same manner 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. After that, the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, and it was found that the composition of each disk-shaped ceramic matched the composition at the time of weighing. Further, the Pb component contained in each disk-shaped ceramic (Examples 32 to 37) was less than 1000 ppm.

Next, in the same manner as in Examples 1 to 5, a strip-shaped element is produced from each disk-shaped ceramic, and each strip-shaped element is subjected to the first polarization treatment and the second polarization as in Examples 15 to 20. After processing, piezoelectric elements according to the present invention (Examples 32 to 37) were produced. Thereafter, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature in the same manner as in Examples 1-5. 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 housed in a constant temperature bath (SH-261 manufactured by Espec Co., Ltd.), the ambient temperature of the constant temperature bath was changed, and the dielectric of each piezoelectric element was measured by the parallel plate capacitor method. The temperature dependence of the modulus was measured and the Curie temperature _TC was determined. At this time, an AC electric field with a frequency of 1 kHz and an electric field strength of 10 V/cm was applied to each piezoelectric element. The temperature of the constant temperature bath was changed from room temperature to 150° C. at a rate of 5° C./min, and the temperature was maintained for 5 minutes after changing the temperature. The measurement results and calculation 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 housed in a constant temperature bath (SH-261 manufactured by Espec Co., Ltd.), and the atmospheric temperature of the constant temperature bath was changed, and each piezoelectric element was measured by a resonance/antiresonance method. was measured at −30° C. (hereinafter referred to as “Q _{m , −30° C.} ”). Here, after changing the temperature of each piezoelectric element to −30° C., the temperature 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 to 37), through the same steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric elements according to the present invention (Examples 32 to 37), similarly to Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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 circle diameter of the crystal grains of the piezoelectric elements according to the present invention (Examples 32 to 37) was 2.8 μm.

In any of Examples 32 to 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 to 37, the crystal grains A having the first domain and the crystal grains B having the second domain were both present at 5% by number or more, and at room temperature The absolute value of _d31 was 120 pm/V or more, and the _Qm was also 1200 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 have small elastic loss during vibration. In particular, when Bi/(A+B) is 0.15 mol% or more and 0.41 mol% or less, Q m at −30° C. (Q _{m , −30° C.} ) is 350 or more, so elastic loss at low temperature was found to be able to 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 the amounts of Ba, Ca, Ti, Zr, and Mn in the above formula (1) were x = 0.06, y = 0. Weighed and mixed to meet composition of .030 and z=0.008. Appropriate amounts of barium carbonate and titanium oxide were added so that a in the above formula (1) had the value shown in Table 11 of FIG. After that, 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 to 5. After that, using an electric furnace, the produced molded body was first heated at 600 ° C. in an air atmosphere, and then heated to the firing temperature shown in Table 11 in FIG. After holding for 0.5 hours, the temperature was lowered to room temperature by natural cooling. As a result, disk-shaped ceramics (Examples 38 to 42) were produced as piezoelectric materials.

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

Then, in the same manner 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. After that, the composition of each disk-shaped ceramic was evaluated by fluorescent X-ray analysis in the same manner as in Examples 1 to 5, and it was found that the composition of each disk-shaped ceramic matched the composition at the time of weighing. In addition, the Pb component contained in each disk-shaped ceramic (Examples 38 to 42) was less than 1000 ppm.

After that, in the same manner as in Examples 1 to 5, strip-shaped elements were produced from each disk-shaped ceramic, each strip-shaped element was subjected to the first polarization treatment, and each strip-shaped element was further subjected to the second polarization treatment. Thus, piezoelectric elements according to the present invention (Examples 38 to 42) were produced. However, in the first polarization treatment, the application time of the DC voltage was set to 100 minutes, and in the second polarization treatment, gold was applied so that an electric field of 650 V/mm in the opposite direction to the electric field of the first polarization treatment was generated in the ceramics. A DC voltage was applied to the electrodes for 13 minutes. Thereafter, d ₃₁ and Q _m of the piezoelectric element according to the present invention were measured at room temperature in the same manner as in Examples 1-5. 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 steps as in Examples 1 to 5, cross-sectional samples for observing crystal grains and domains were produced. The equivalent circle diameter was calculated and the width of the domain was measured. At this time, in the piezoelectric elements according to the present invention (Examples 38 to 42), similarly to Examples 6 to 10, the number density (number %) of the crystal grains A having the first domain and the second domain 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 all 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. Further, in any of Examples 38 to 42, the crystal grains A having the first domain and the crystal grains B having the second domain are present at 5% by number or more, and the absolute value of _d31 at room temperature is It was 80 pm/V or more, and _Qm was also 600 or more. 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 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, and the firing temperature can be set to less than 1500 ° C., which is desirable from the viewpoint of ease of production. Do you get it.

Next, Example 43 will be described. As Example 43, the vibration wave motor 400 described above was manufactured using the piezoelectric element of Example 2 described above. In this vibration wave motor 400, it was confirmed that the output shaft 403 rotated according to the application of the alternating voltage. In addition, Example 44 will be described. As Example 44, the vibration wave motor 400 of Example 43 was used to fabricate the interchangeable lens barrel 500 described above. It was confirmed that the interchangeable lens barrel 500 performs an autofocus operation in response to application of an alternating voltage.

Next, Example 45 will be described. First, a titanium compound, a calcium compound, a zircon compound, bismuth oxide (Bi ₂ O ₃ ), and 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. These mixed powders were then mixed overnight using a ball mill to produce a mixed powder. Next, after adding and mixing PVB to the mixed powder thus produced, the mixture was applied by a doctor blade method, and as a result, a green sheet having a thickness of 50 μm was produced. Further, a conductive paste for internal electrodes was printed on this green sheet. Pd paste was used as the conductive paste. After that, nine green sheets coated with a conductive paste are laminated to form a laminate, and the laminate is heated to 1340° C. and maintained at 1340° C. for 5 hours to prepare a sintered body. did. Next, the sintered body is cut into a size of 10 mm × 2.5 mm, the side surface is polished, and a pair of external electrodes for alternately short-circuiting the layers of the internal electrodes are formed on the side surface. Upper and lower electrodes connected to the electrodes were formed on the upper and lower surfaces by Au sputtering. Thus, a piezoelectric element 300 having a laminated structure was produced. When the internal electrodes of this piezoelectric element 300 were observed, it was found that a plurality of layers of internal electrodes 302 made of Pd and the piezoelectric material layers 301 were alternately formed. Thereafter, the piezoelectric element 300 was subjected to polarization treatment prior to evaluation of piezoelectricity. Specifically, as the first polarization treatment, the piezoelectric element 300 is heated to 100° C. in an oil bath, and a DC 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 . was applied, the piezoelectric element 300 was naturally cooled 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 is applied to the upper electrode 303 and the lower electrode 304 in the opposite direction to the electric field of the first polarization treatment. A DC voltage was applied for 10 minutes in between, followed by quenching. When the piezoelectric properties of the piezoelectric element 300 produced at this time were evaluated, it was confirmed that the piezoelectric element 300 had sufficient insulating properties and had good piezoelectric properties equivalent to those of the piezoelectric material of the first embodiment.

Next, Example 46 will be described. As Example 46, the piezoelectric element 300 of Example 45 was used to fabricate the vibration wave motor 407 described above. In this vibration wave motor 407, it was confirmed that the rotor 410 rotated according to the application of the alternating voltage. In addition, Example 47 will be described. As Example 47, using the vibration wave motor 407 of Example 46, the interchangeable lens barrel 500 described above was manufactured. It was confirmed that the interchangeable lens barrel 500 performs an autofocus operation in response to application of an alternating voltage. Further, Example 48 will be described. As Example 48, the above-described digital camera 700 was manufactured using the piezoelectric element of Example 2. FIG. In this digital camera 700, it was confirmed that the speaker operated according to the application of the alternating voltage.

Next, Example 49 will be described. As Example 49, using the piezoelectric element 300 of Example 45, the piezoelectric actuator 10011 described above was produced. Furthermore, using this piezoelectric actuator 10011, an ultrasonic probe 1001 shown in FIG. 8A was produced. In this ultrasonic probe 1001, it was confirmed that an operation of transmitting an ultrasonic wave following an input electrical signal and an operation of receiving an ultrasonic wave reflected from a subject were performed. Also, using the ultrasonic probe 1001 described above, an ultrasonic inspection apparatus shown in FIG. 8B was produced. In this ultrasonic inspection apparatus, it was confirmed that an ultrasonic image with reduced noise was generated from vibration data of ultrasonic waves input and output.

The piezoelectric material according to the present invention can exhibit good and stable piezoelectricity over a wide range of operating temperatures. In addition, since it does not contain lead, the load on the environment can be reduced. In addition, the piezoelectric material according to the present invention can also be used without problems in equipment that uses a large amount of piezoelectric material, such as vibration wave motors, optical equipment equipped with the vibration wave motor, and electronic equipment.

200, 300, 405, 412 Piezoelectric element 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, and O,
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 with a width of 300 nm or more and 800 nm or less, and a crystal grain B having a second domain with a width of 20 nm or more and 50 nm or less. and
A piezoelectric material having a mechanical quality factor of 600 or more at room temperature . 5% or more of the crystal grains A having the first domain and 5% or more of the crystal grains B having the second domain among the plurality of crystal grains Item 1. The piezoelectric material according to item 1. 3. The piezoelectric material according to claim 1, wherein the crystal grains A include crystal grains A having both the first domain and the second domain. 3. The piezoelectric material according to claim 1, wherein the crystal grains B include crystal grains B having both the first domain and the second domain. 5. A piezoelectric material as claimed in any one of the preceding claims, characterized in that the first domains extend beyond grain boundaries of adjacent grains. 6. The piezoelectric material according to any one of claims 1 to 5, wherein the Pb component contained is less than 1000 ppm. 7. The method of claims 1 to 6, wherein x, which is the ratio of the number of moles of Ca contained 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 items 1 and 2. 1 to 1, wherein y, which is the ratio of the number of moles of Zr contained to the sum of the number of moles of Ti, Zr, and Mn contained, is 0.01 ≤ y ≤ 0.095. 8. The piezoelectric material according to any one of 7. Equipped with an electrode and a piezoelectric material part,
A piezoelectric element, wherein the piezoelectric material constituting the piezoelectric material portion is the piezoelectric material according to any one of claims 1 to 8. 10. The piezoelectric element according to claim 9, wherein the piezoelectric material portions and the electrodes are alternately laminated. 11. A vibration wave motor, comprising: a vibrating body in which the piezoelectric element according to claim 9 or 10 is arranged; and a moving body. 12. An optical apparatus comprising a driving section, wherein the driving section has the vibration wave motor according to claim 11. An electronic device comprising the piezoelectric element according to claim 9 or 10.

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