JP4268111B2 - Piezoelectric single crystal, piezoelectric single crystal element, manufacturing method thereof, and 1-3 composite piezoelectric element - Google Patents

Description

The present invention relates to a piezoelectric single crystal, a piezoelectric single crystal element and a method for manufacturing the same, and a 1-3 composite piezoelectric element as shown in FIG. 1, and in particular, an electromechanical coupling coefficient (k ₃₁ , k ₃₃ ) and piezoelectric distortion. Piezoelectric single crystal elements (such as constants (d ₃₁ , d ₃₃ )) that are much better than conventional sintered piezoelectric elements (for example, lead zirconate titanate Pb (Zr, Ti) O ₃ (PZT)) For example, magnesium niobate Pb (Mg _{l / 3} Nb _2/3 ) O ₃ -lead titanate PbTiO ₃ (PMN-PT) single crystal or zinc niobate Pb (Zn _{l / 3} Nb _2/3 ) O _3- This is to improve the yield of lead titanate PbTiO ₃ (produced from a single crystal of PZN-PT or PZNT).

The piezoelectric single crystal element has, for example, a rectangular parallelepiped as shown in FIG. 2, the longitudinal direction of which is the polarization direction 3 (or PD), and the polarization direction 3 (or PD) when a voltage is applied to the polarization direction 3 (or PD). represents vibration (longitudinal vibration) of the longitudinal vibration mode that is proportional to the square root of the conversion efficiency of electrical energy and mechanical energy of the size electromechanical coupling factor k ₃₃ of) the efficiency higher the number is Means good. Further, for a plate-like piezoelectric single crystal element as shown in FIG. 3, the electromechanical coupling coefficient k in the direction 1 (lateral vibration mode) orthogonal to the polarization direction 3 (hereinafter, the polarization direction is referred to as PD). Regarding ₃₁ , it means that the larger this figure, the better the efficiency. Note that the piezoelectric single crystal element may have a shape of a rod-like body, a rectangular plate, a circular plate, or the like in addition to the above-described rectangular parallelepiped or plate-like body, and the electromechanical coupling coefficient can be similarly determined for each shape.

Regarding the piezoelectric single crystal element, for example, Patent Document 1 discloses an ultrasonic probe using a piezoelectric body made of a solid solution single crystal of lead zinc niobate-lead titanate (PZN-PT). This technique shows that such a piezoelectric body has a large electromechanical coupling coefficient (k ₃₃ ) in the polarization direction of 80 to 85%, and that a single-crystal can be used to obtain a highly sensitive probe. .

On the other hand, a piezoelectric single crystal ingot and wafer (substrate) made of lead zinc niobate-lead titanate (PZN-PT) are made of lead zirconate titanate Pb (Zn, Ti) O ₃ (conventional piezoelectric element material). PZT) is known to be expensive. This situation has a piezoelectric single crystal consisting of lead magnesium niobate-lead titanate (PMN-PT) using lead magnesium niobate (PMN) instead of lead zinc niobate (PZN) and other similar compositions The same applies to the case of a piezoelectric single crystal.

  The following three points can be cited as factors that make such piezoelectric single crystal ingots and wafers expensive.

  The first factor is considered to be caused by the evaporation of lead oxide (PbO) during single crystal growth. Using piezoelectric raw material powder, pre-fired body or sintered body, these are melted and solidified in one direction, so-called melt Bridgman method, or dissolved in a solution using flux Later, when a single crystal is grown by the so-called solution Bridgman method, which solidifies in one direction, the vapor pressure of lead oxide (PbO) present as a component or flux is high at the single crystal growth temperature. As a result of violent evaporation, a pyrochlore phase that is out of phase and has a low piezoelectric property is precipitated by deviating from the desired composition ratio in the solidified solid thereafter, and the yield decreases due to the presence of the pyrochlore phase. At the same time, when the pyrochlore phase is precipitated at the lower part of the crystal, a large number of small crystals whose crystal orientations are not aligned in the part that is precipitated above the part Crystal precipitation is observed. This part is not a single crystal but a polycrystal and cannot be used as a piezoelectric single crystal element. Therefore, the yield (specifically, crystal yield or wafer yield) of the piezoelectric single crystal element is significantly reduced. The term “crystal yield” as used herein means the percentage (%) of the mass of a healthy single crystal part free from the pyrochlore phase and thermal cracks with respect to the mass of the charged raw material. “Wafer yield” refers to the pyrochlore phase or thermal phase of the obtained single crystal portion with respect to the number of wafers obtained by cutting a desired thickness in a desired orientation with a cutting tool such as a wire saw. It means the percentage (%) of the number of healthy wafers without cracks.

  The second factor is considered to be caused by the occurrence of cracks during single crystal growth. When the single crystal is grown by the melt Bridgman method or the solution Bridgman method in the course of cooling to room temperature during and after the growth of the single crystal, the temperature difference generated in the crystal growth direction in the crucible, and the crucible Single crystal cracks (thermal cracks) are likely to occur during the growth process and the cooling process due to thermal strain caused by the temperature difference generated between the outer surface of the single crystal in contact with the inner wall and the center of the single crystal. . When this crack occurs, it cannot be used as a piezoelectric single crystal element. Therefore, the yield (specifically, crystal yield or wafer yield) of the piezoelectric single crystal element is significantly reduced. In addition, this crack tends to occur more frequently as the crystal quality is better and the quality is higher.

  The third factor is considered to be caused by the occurrence of chipping during the processing of the piezoelectric single crystal element. When the single crystal is grown by the melt Bridgman method or the solution Bridgman method, the wafer is cut out from the obtained piezoelectric single crystal ingot, and when the single crystal plate having a desired piezoelectric element shape is cut out, the single crystal plate Fine cracks (chipping) occur in the vicinity of the end face of the cut surface. When such chipping occurs in a single crystal plate, even if the single crystal plate in which this chipping has occurred is polarized to produce a piezoelectric element, the desired piezoelectric characteristics cannot be obtained, resulting in a defective product. Therefore, the yield (single crystal plate yield) of the piezoelectric single crystal element is significantly reduced. The term “single crystal plate yield” as used herein means that the obtained wafer is cut into a desired dimension with a cutting tool such as a dicing saw and the soundness without chipping relative to the number of single crystals obtained by cutting. It means the percentage (%) of the number of single crystal plates.

  In this way, when the piezoelectric single crystal is grown using the powder, raw calcined body or sintered body of the component raw material of the piezoelectric single crystal to produce the piezoelectric single crystal plate and the piezoelectric single crystal element, the piezoelectric single crystal element The yield (specifically, the crystal yield, wafer yield, and single crystal plate yield) is inevitably lowered, and as a result of the increase in product cost, there are problems such as limitations on application fields.

JP-A-6-38963

The object of the present invention is to add specific additives to lead magnesium niobate-lead titanate (PMN-PT) single crystal or lead zinc niobate-lead titanate (PZN-PT or PZNT) single crystal. Accordingly, an object of the present invention is to provide an inexpensive piezoelectric single crystal element excellent in piezoelectric characteristics such as electromechanical coupling coefficients (k ₃₁ , k ₃₃ ) and piezoelectric strain constants (d ₃₁ , d ₃₃ ).

  Another object of the present invention is to provide a piezoelectric single crystal suitable for use in manufacturing the piezoelectric single crystal element, a method for manufacturing the piezoelectric single crystal element, and a 1-3 composite piezoelectric element formed by a plurality of the piezoelectric single crystal elements. It is to provide an element.

In order to achieve the above object, the gist of the present invention is as follows.
(1) A piezoelectric single crystal is a piezoelectric single crystal having a composite perovskite structure, such as lead magnesium niobate [Pb (Mg _{l / 3} Nb _2/3 ) O ₃ ] or lead zinc niobate [Pb (Zn _{l / 3} Nb). _2/3 ) O ₃ ]: 35 to 98 mol%, and lead titanate [PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to A piezoelectric single crystal comprising 30 mol%, wherein 0.05 to 10 mol% of lead in the composition is replaced with calcium.

(2) In a piezoelectric single crystal having a composite perovskite structure, lead magnesium niobate [Pb (Mg _{l / 3} Nb _2/3 ) O ₃ ] or lead zinc niobate [Pb (Zn _{l / 3} Nb _2/3 ) O ₃ ]: 35 to 98 mol%, and lead titanate [PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to 30 mol% A composition, wherein 0.05 to 10 mol% of lead in the composition is replaced with calcium, and one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta A piezoelectric single crystal containing 5 mol% or less in total.

(3) The [001] direction of the ingot of the piezoelectric single crystal described in (1) or (2) above is defined as the polarization direction, and the [100] direction, [010] direction or [110] direction substantially orthogonal thereto is the single crystal. A piezoelectric single crystal element that uses an electromechanical coupling coefficient (k ₃₁ ) of a transverse vibration mode that is normal to an end face of the element,
The normal direction of the end face is a piezoelectric single crystal element having a solid angle range of [100] axis ± 15 °, [010] axis ± 15 °, or [110] axis ± 5 °.

(4) The [001] direction of the piezoelectric single crystal ingot described in (1) or (2) above is a polarization direction, and a vibration mode in a direction parallel thereto, that is, a longitudinal vibration having a (001) plane as an end face A piezoelectric single crystal device using a mode electromechanical coupling coefficient (k ₃₃ ),
When the length or diameter of the minimum side of the element end face perpendicular to the polarization direction is a and the element length in the direction parallel to the polarization direction is b, a and b satisfy the relational expression b / a ≧ 2.5. Piezoelectric single crystal element.

(5) The [110] direction of the piezoelectric single crystal ingot described in the above (1) or (2) is a polarization direction, and a vibration mode in a direction parallel thereto, that is, a longitudinal vibration having a (110) plane as an end face A piezoelectric single crystal device using a mode electromechanical coupling coefficient (k ₃₃ ),
When the length or diameter of the minimum side of the element end face perpendicular to the polarization direction is a and the element length in the direction parallel to the polarization direction is b, a and b satisfy the relational expression b / a ≧ 2.5. Piezoelectric single crystal element.

(6) 1-3 formed by arranging a plurality of the piezoelectric single crystal elements described in the above (4) or (5) so that element end faces perpendicular to the polarization direction are located in the same plane. Composite piezoelectric element.

(7) The single crystal ingot or the cut single crystal element material should be polarized before and after the single crystal element material having a predetermined shape is cut out in a predetermined direction from the piezoelectric single crystal ingot described in (1) or (2) above. Apply a DC electric field of 350 to 1500 V / mm in the temperature range of 20 to 200 ° C, or apply a DC electric field of 350 to 1500 V / mm at a temperature higher than the Curie temperature (Tc) of the single crystal element material. A step of polarizing a single crystal ingot or a single crystal element material by cooling to room temperature while
The method for producing a piezoelectric single crystal element according to any one of (3) to (5), wherein:

(8) magnesium niobate _{[Pb (Mg l / 3 Nb} 2/3) O 3] or lead zinc niobate _{[Pb (Zn l / 3 Nb} 2/3) O 3]: 35~98mol%, and titanium A composition containing lead oxide [PbTiO ₃ ]: 0.1 to 64.9 mol% and lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to 30 mol%, Before and after cutting a single crystal element material of a predetermined shape in a predetermined direction from a piezoelectric single crystal ingot in which 0.05 to 10 mol% of lead is replaced with calcium, the single crystal ingot or the cut single crystal element material should be polarized Apply a DC electric field of 350 to 1500 V / mm in the temperature range of 20 to 200 ° C, or apply a DC electric field of 350 to 1500 V / mm at a temperature higher than the Curie temperature (Tc) of the single crystal element material. A step of polarizing a single crystal ingot or a single crystal element material by cooling to room temperature while
A method for manufacturing a piezoelectric single crystal element having

(9) In the above (8), one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta are further added to the piezoelectric single crystal ingot in a total amount of 5 mol% or less. A method of manufacturing the included piezoelectric single crystal element.

  According to the present invention, a piezoelectric single crystal element comparable to a lead-based perovskite structure single crystal having no additive such as lead indium niobate and Ca can be produced. Furthermore, the appearance of a pyrochlore phase, which is a different phase during the growth of lead-based perovskite structure single crystals without additives such as lead indium niobate and Ca, and the crystal yield due to the occurrence of thermal cracks during cooling after the growth of the single crystal The reduction in wafer yield was improved. In addition, the decrease in the yield of the single crystal plate due to the occurrence of chipping for cutting the single crystal plate from the obtained wafer was also improved. As a result, it has become possible to manufacture at a sufficiently low cost compared to a piezoelectric single crystal element manufactured from a lead-based perovskite structure single crystal having no additive such as lead indium niobate and Ca. It has become possible to supply piezoelectric single crystal elements that can be adapted to application fields.

The piezoelectric single crystal and the piezoelectric single crystal element produced from the piezoelectric single crystal have a value of an electromechanical coupling coefficient k _{33 in} the polarization direction (longitudinal vibration mode) of the piezoelectric single crystal element of 80% or more, so that it can be used in various applications. It is a promising material. However, since the yield of the piezoelectric single crystal element is low, it is expensive, so the fields actually used are limited. The inventors of the present invention have focused on the fact that they are used only for products with high added value, that is, products that can absorb expensive material prices in the product price.

  The growth of the pyrochlore phase, which is a different phase during the growth of the piezoelectric single crystal, is caused by the evaporation of lead oxide (PbO) during the growth, which inhibits the formation of the desired single crystal of the composite perovskite phase. We have found that this is a factor that lowers the yield.

  Further, in the cooling process during and after the growth of the single crystal, a large number of thermal cracks are caused by thermal strain caused by the temperature difference generated between the growth directions of the single crystal and between the central portion and the outer surface of the single crystal. It has been found that the occurrence of such thermal cracks is a factor that reduces the yield.

  Furthermore, when a wafer is cut from a single crystal ingot with few pyrochlore phases and thermal cracks with a wire saw, and further cut into a single crystal plate in the shape of a piezoelectric single crystal element using a dicing saw or the like, the end face of the cut surface of the single crystal plate Chipping, which is a fine crack, is likely to occur, and even if the single crystal plate with chipping is polarized, it cannot be used as a piezoelectric single crystal element. Therefore, the occurrence of such chipping is a factor that lowers the yield. I found it.

Due to the above factors, the present inventors have found that a piezoelectric single crystal element made from the piezoelectric single crystal has an electromechanical coupling coefficient k ₃₃ of 80% or more in the polarization direction PD (longitudinal vibration mode) of the piezoelectric single crystal element. It has been found that it is used only in a limited field because it has a low yield and is expensive despite being a promising material for various applications.

  In order to make the high-priced piezoelectric single crystal element a reasonable price and apply it to various applications, the inventors have achieved excellent piezoelectric characteristics of the piezoelectric single crystal element while suppressing a decrease in yield due to the factor. Researched how to maintain. As a result, the piezoelectric single crystal can be achieved by using a specific additive, more specifically, a piezoelectric single crystal with an optimized composition by adding both lead indium niobate and calcium as additives. I found it.

Hereinafter, the present invention will be described in detail.
The piezoelectric single crystal having the composite perovskite structure of the present invention is, for example, a solid solution single crystal of lead magnesium niobate-lead titanate (PMN-PT) or lead zinc niobate-lead titanate (referred to as PZN-PT or PZNT). The unit cell is a composite perovskite structure as schematically shown in FIG. 5 (Pb ions are present at the corners of the unit cell, and any of Mn, Zn, Nb, and Ti is located at the body center of the unit cell) Structure with element ions).

  However, with the single crystal plate cut from the grown single crystal ingot, the direction of the electric dipole in the domain consisting of the set of electric dipoles in the same direction in the polarization direction PD and the direction orthogonal thereto is Since each domain is directed in various directions, it does not exhibit piezoelectricity and is in an unpolarized state.

By selecting the polarization treatment temperature and the applied electric field, which are commonly used polarization conditions, and applying the electric field to the polarization direction PD for polarization, the electric bipolars in many domains that are oriented in various directions for each domain for the first time The direction of the child can be aligned with the polarization direction PD (one direction). Accordingly, the electromechanical coupling coefficient k ₃₃ in the polarization direction PD is, for example, in the case of lead zinc niobate-lead titanate (PZN-PT) or lead magnesium niobate-lead titanate (PMN-PT). It shows a large value of 80% or more.

However, the sequence of the domain in a direction perpendicular to the polarization direction PD, which becomes a problem when the piezoelectric single crystal device using the electromechanical coupling factor k ₃₁ in the lateral vibration mode, in the above polarization treatment, can not be properly controlled. Originally, the appropriate selection of the cutting direction of the element in the plane orthogonal to the polarization direction PD of the cut element material, and the polarization condition in the polarization direction PD, that is, only within the appropriate range of the polarization treatment temperature and the applied electric field. It is possible to control.

Hereinafter, the reasons for limitation of the piezoelectric single crystal element of the present invention will be described.
(1) Crystal structure of piezoelectric single crystal element (composite perovskite structure):
The crystal structure targeted by the present invention is that the unit cell of the solid solution single crystal is schematically shown in FIG. 5, and the Pb ions are located at the corners of the unit cell and the oxygen ions are at the center of the unit cell. And a perovskite structure (RMO ₃ ) in which the M ions are located in the body center of the unit cell, and more than one M ion at the body center position in FIG. It is necessary to have a composite perovskite structure composed of any one of a plurality of element ions (specifically, Mg, Nb, Zn, In).
Furthermore, a structure in which one or more of Mn, Cr, Sb, W, Al, La, Li, and Ta are arranged at the body center position or inter-lattice position of the unit cell is also within the scope of the present invention.

(2) Single crystal element shape:
The shape of the “piezoelectric single crystal element” targeted by the present invention can be classified into the following two types depending on the application.

(A) When using the electromechanical coupling coefficient k ₃₃ in the direction of the polarization direction PD (longitudinal vibration mode):
The [001] direction of an ingot of the piezoelectric single crystal and the polarization direction PD, thereto parallel vibration mode, i.e., the piezoelectric single utilizing longitudinal vibration mode electromechanical coupling coefficient k ₃₃ of the end surface (001) In the case of producing a crystal element, the piezoelectric single crystal element B of FIG. 6 and a rectangular parallelepiped, a rod-like body or a plate-like body as shown in FIG. In particular, a desirable element shape is such that when the length or diameter of the minimum side of the element end face T orthogonal to the polarization direction is a and the element length in the direction parallel to the polarization direction PD is b, a and b are b It is preferable to satisfy the relational expression of /a≧2.5, more preferably b / a ≧ 3.0. When b / a <2.5, the element length b is close to the other length (a or c), and the natural frequency approaches, so that it may not be possible to effectively extract only the vertical vibration. Because there is.

Further, by using the piezoelectric single crystal, the electric machine of the longitudinal vibration mode in which the [110] direction of the ingot is the polarization direction PD and the vibration mode is parallel to the polarization direction PD, that is, the (110) plane is the end face T. when fabricating the piezoelectric single crystal device using the coupling coefficient k ₃₃ is also the same reason, it is preferable that a and b satisfy the relationship of b / a ≧ 2.5.

(B) When using the electromechanical coupling factor k ₃₁ in the direction 1 orthogonal to the polarization direction PD (lateral vibration mode):
As shown in the piezoelectric single crystal element A of FIG. 6, the [001] direction is the polarization direction PD, and the [100] direction vibration mode is almost perpendicular to the polarization direction PD, that is, the transverse vibration mode is the (100) plane is the end face T. When the piezoelectric single crystal element using the electromechanical coupling coefficient k ₃₁ is manufactured, the piezoelectric single crystal element A or a plate-like body as shown in FIG. In particular, a desirable element shape is a plate-shaped body (a / c ≧ 2.5, a >> L, c >> L) having a slenderness ratio (aspect ratio: a / c) of 2.5 or more, and more desirably, a slenderness ratio ( Aspect ratio: a / c) is a plate-like body having 3 or more.
In addition, the shape of the both ends (short side c) of the plate-shaped body of the present invention may be a convex curve c ′ (dotted line) or a concave curve c ″ (one point) as shown in FIG. It may be a chain line). Further, it may be a rectangular plate with a = c. The element end face in the present invention means a short side c perpendicular to the long side a in FIG. Therefore, the normal direction 1 of the element end face c is parallel to the long side a of the element.

(3) The normal direction 1 of the piezoelectric element end face T using the electromechanical coupling coefficient k ₃₁ in the direction 1 (lateral vibration mode) orthogonal to the polarization direction PD is the [100] direction, the [010] direction, or the [110] direction. ] When the direction is 0 °, within the solid angle range of [100] axis ± 15 °, [010] axis ± 15 ° or [110] axis ± 5 °, respectively:
As shown in the piezoelectric single crystal element A in FIG. 6, the [001] direction is the polarization direction PD, and the (001) plane, which is a plane including the [100] direction or the [010] direction substantially orthogonal thereto, is cut vertically. When producing a piezoelectric single crystal element using the electromechanical coupling coefficient k ₃₁ in the transverse vibration mode with the surface being the normal direction 1 of the element end face T, the normal direction 1 of the end face T of the piezoelectric single crystal element is When the [100] direction is 0 °, as shown in FIG. 7 (a), it is within the range of a conical solid angle of 0 ° ± 15 ° ([100] axis ± 15 °), and The normal direction 1 of the end face T of the piezoelectric single crystal element is 0 ° ± 15 ° ([010] axis ± 15 °) as shown in FIG. 7B when the [010] direction is 0 °. When the normal direction 1 of the end face T of the piezoelectric single crystal element is within the range of the conical solid angle and the [110] direction is 0 °, as shown in FIG. ± 5 ° It is preferable to be within the range of the solid angle of [[110] axis ± 5 °).

  Here, the normal direction n of the widest surface of these piezoelectric single crystal elements is as shown in FIGS. 7A to 7C when the [001] direction of the polarization direction is 0 °. Is within a conical solid angle within the [001] axis ± 15 ° (0 ° ± 15 °).

The reason why the normal direction 1 of the end face T of the element utilizing the lateral vibration is limited to such an angle range is considered as follows. That is, the normal direction 1 of the piezoelectric element end face T is the range of the angle θ outside the solid angle range of [100] axis ± 15 °, [010] axis ± 15 °, or [110] axis ± 5 ° 15. In the range of ° <θ <40 ° and 50 ° <θ <75 °, between the <100> direction and the <110> direction in the plane perpendicular to the polarization direction <100> axis, <310>, <210> , <320> and other low-index crystal axis orientations exist, and the transverse vibration modes are dispersed in those directions. Therefore, spurious (curve disturbance) occurs in the impedance curve of the transverse vibration mode, the frequency range of the vibration mode (more specifically, the difference between the resonant frequency f _R and the anti-resonance frequency f _a) is or narrowed. As a result, the electromechanical coupling factor k ₃₁ in the lateral vibration mode is considered to decrease.

The composition of the piezoelectric single crystal of the present invention is as follows: lead magnesium niobate or zinc zinc niobate: 35 to 98 mol% and lead titanate: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _1/2 Nb _1/2 ) 0 ₃ ]: a composition containing 0.1 to 30 mol%, characterized in that 0.05 to 10 mol% of lead in the composition is replaced with calcium.
In this composition, lead magnesium niobate or zinc zinc niobate and lead titanate, lead indium niobate and 0.05 to 10 mol% of lead in the composition are replaced with calcium for the following reasons.

(4) Lead magnesium niobate Pb (Mg _1/3 Nb _2/3 ) 0 ₃ (PMN) or zinc niobate Pb (Zn _1/3 Nb _2/3 ) 0 ₃ (PZN): 35 to 98 mol% :
Lead magnesium niobate or lead zinc niobate is the main composition of the present invention. When the content is less than 35 mol%, the grown single crystal element does not exhibit desired piezoelectric characteristics (for example, k value, d value). When the content exceeds 98 mol%, a single crystal having a size suitable for practical use cannot be grown.
The preferable range of lead magnesium niobate is 50 to 98 mol%, and the preferable range of lead zinc niobate is 80 to 98 mol%.

In addition, the molar ratio of Mg / Nb Mg / Nb in lead magnesium niobate Pb (Mg _1/3 Nb _2/3 ) 0 ₃ is 0.5, but is not limited to this. If the molar ratio of Nb is in the range of 0.45 to 0.54, it is within the scope of the present invention. Therefore, the lead magnesium niobate Pb (Mg, Nb) 0 ₃ may be expression. Similarly, the Zn / Nb ratio Zn / Nb molar ratio in the zinc zinc niobate Pb (Zn _1/3 Nb _2/3 ) 0 ₃ is 0.5, but is not limited to this. If the molar ratio of / Nb is in the range of 0.45 to 0.54, it is within the scope of the present invention. Therefore, zinc zinc niobate may be expressed as Pb (Zn, Nb) O ₃ .

In addition, as a composition containing lead magnesium niobate or zinc zinc niobate: 35 to 98 mol% and lead titanate: 0.1 to 64.9 mol%, known compositions such as lead magnesium niobate / lead titanate ( Typical examples: [Pb (Mg _1/3 Nb _2/3 ) 0 ₃ ] _0.68 [PbTiO ₃ ] _0.32 (PMN68-PT32)), lead zinc niobate / lead titanate (typical example: [Pb (Zn _{1 / 3} Nb _2/3 0 ₃ ) _0.91 [PbTiO ₃ ] _0.09 (PMN91-PT9)] is well known.

(5) Lead indium niobate [Pb (In _1/2 Nb _1/2 ) 0 ₃ ]: 0.05-30 mol%:
The ionic radius of indium (In) in lead indium niobate is larger than that of magnesium (Mg) and zinc (Zn), but smaller than that of niobium (Nb), so the core of the unit cell of perovskite structure Lattice distortion caused by the difference in ionic radius between niobium (Nb) and magnesium (Mg) or zinc (Zn) placed at the position is alleviated, generating cracks during single crystal growth and chipping during piezoelectric element processing Has the effect of making it difficult to occur. Therefore, in the present invention, it is necessary to add 0.05 mol% or more of lead indium niobate in order to exert the above-described effect. However, addition of more than 30 mol% increases the melting point of the raw material when growing the single crystal. This is not preferable because process management becomes difficult during production.

The In / Nb ratio In / Nb molar ratio of In / Nb in lead indium niobate [Pb (In _1/2 Nb _1/2 ) 0 ₃ ] is 1, but is not limited to this. If the In / Nb molar ratio is in the range of 0.95 to 1.04, it is within the scope of the present invention. Therefore, the lead indium niobate Pb (In, Nb) 0 ₃ may be expression.

(6) Lead titanate PbTiO ₃ (PT): 0.1-64.9mol%:
Since the remainder of lead magnesium niobate or lead zinc niobate specified above is 35 to 98 mol% and lead indium niobate: 0.05 to 30 mol% is lead titanate, the upper limit of the lead titanate is 64.9 mol %. If the lead titanate is less than 0.1 mol%, the grown single crystal element does not exhibit desired piezoelectric characteristics (k value, d value), so 0.1 mol% or more is contained.

(7) 0.05 to 10 mol% of lead in the crystal lattice is replaced with calcium:
In order to replace 0.05 to 10 mol% of lead in the composition of the single crystal ingot (in the crystal lattice) with calcium, it is necessary to add calcium in consideration of the amount of evaporation of calcium during growth of the single crystal. . The method for adding calcium is not particularly defined. For example, calcium-substituted magnesium magnesium niobate, calcium-substituted zinc niobate, or calcium-substituted lead titanate may be used. Alternatively, a method of adding calcium oxide or calcium carbonate to the raw material may be used. When calcium oxide is added to the raw material, during the growth of the single crystal, calcium (Ca) in the calcium oxide contains three lead-based perovskite structure compounds (lead magnesium niobate or lead zinc niobate and lead titanate). The lead (Pb) site (R ion in FIG. 5) of the crystal lattice made of a solid solution of lead indium niobate is disposed as a substitutional atom, and has the effect of suppressing the evaporation of lead oxide at a high temperature. As a result of the action of Ca being able to suppress the formation of the pyrochlore phase, it facilitates the formation of a desired single crystal of the composite perovskite phase. In the present invention, in order to exert the above action of Ca, it is necessary to replace calcium by 0.05 mol% or more, but substitution exceeding 10 mol% makes it difficult to grow a single crystal. For this reason, it is preferable that 0.05 to 10 mol% of lead in the crystal lattice is replaced with calcium. Furthermore, it is preferable that 0.05 to 5 mol% is replaced with calcium.

(8) A total of 5 mol% or less of one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta:
When it is necessary to increase the relative dielectric constant ε _r or the mechanical quality factor Q _m , one or more selected from Mn, Cr, Sb, W, Al, La, Li and Ta are further added. You may add 5 mol% or less of a total element. This is because addition exceeding 5 mol% in total makes it difficult to obtain a single crystal and may result in polycrystal.

Effect of adding these elements, it is possible to suppress the increase and aging of the mechanical quality factor Q _m for example Mn, by adding Cr. In order to obtain this effect, it is preferable to add a total of 0.05 mol% of one or two elements selected from Mn and Cr. Further, the addition of Sb, La, W, Ta improves the relative dielectric constant. In order to obtain this effect, it is preferable to add at least 0.05 mol% of one or more elements selected from Sb, La, W and Ta in total. Al and Li contribute to stabilization during the growth of the single crystal. In order to obtain the effect, it is preferable to add 0.05 mol% or more of one or two elements selected from Al and Li in total.

(9) Other impurities In addition, impurities such as Fe, Pt, Au, Pd, and Rh may be mixed from raw materials and crucibles in the process of manufacturing a piezoelectric single crystal. Therefore, it is desirable to keep the total to 0.5 mol% or less.

(10) 1-3 Composite Piezoelectric Element The 1-3 composite piezoelectric element of the present invention is a parallel type in which the first phase is a piezoelectric single crystal and the periphery is surrounded by a polymer or the like as the second phase as shown in FIG. This refers to the shape of a composite (reference: Ceramics Engineering Handbook, edited by Japan Ceramic Society, pages 1917-1925). In the present invention, when a 1-3 composite piezoelectric element is formed using a plurality of piezoelectric single crystal elements using k ₃₃ in the longitudinal vibration mode, the element end face T perpendicular to the polarization direction is in the same plane. It is preferable to arrange so that it may be located. The number of piezoelectric single crystal elements used when forming one 1-3 composite piezoelectric element and the arrangement pattern of the piezoelectric single crystal elements are determined according to the application.

Next, the suitable manufacturing method of the piezoelectric single crystal element of this invention is demonstrated.
The method for manufacturing a piezoelectric single crystal element of the present invention includes a step of manufacturing a single crystal ingot, a step of cutting a single crystal element material of a predetermined shape from the single crystal ingot in a predetermined direction, and polarization of the single crystal element material It has a main polarization step in which an electric field is applied in a direction to polarize the single crystal element material under a predetermined condition, or an auxiliary polarization step before and after the main polarization step. Note that the method for manufacturing a single crystal element is not limited to the above-described treatment. For example, after determining the crystallographic orientation, the single crystal ingot is subjected to polarization treatment, and the single crystal ingot is formed into a single crystal having a predetermined shape. You may perform the process which cuts out element material to a predetermined direction.

Hereinafter, the reasons for limitation of the production method of the present invention in each step will be described.
(1) Manufacture of single crystal ingot:
Magnesium lead niobate [Pb (Mg _1/3 Nb _1/3 ) 0 ₃ ] or zinc niobate [Pb (Zn _1/3 Nb _2/3 ) 0 ₃ ]]: 35 to 98 mol%, and lead titanate [PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _1/2 Nb _1/2 ) 0 ₃ ]: 0.05 to 30 mol% of a composition comprising lead in the composition In the composition in which 0.05 to 10 mol% of calcium is replaced with calcium, if necessary, one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta are added. The method for producing a single crystal ingot with 5 mol% or less added is a method in which a powdery powder, a pre-sintered body or a sintered body adjusted to the above composition is dissolved in a flux and then cooled and solidified. There is a method of obtaining a single crystal by solidifying in one direction after being melted by heating above the melting point. As the former method, there is a solution Bridgman method or TSSG method (Top Seeded Solution Growth), and as the latter, there is a melting Bridgman method, CZ method (Chocoralsky method), etc. Not specified. In particular, in the case of lead zinc niobate-lead titanate (PZN-PT), the solution Bridgman method or the TSSG method is preferable.

(2) Determination of crystallographic orientation of single crystal ingot:
In the present invention, a method for determining the crystallographic orientation of a single crystal ingot is not particularly defined. For example, when the [001] direction of a single crystal ingot is the polarization direction PD, the [001] axis orientation of the single crystal ingot is generally determined by the Laue method, and at the same time, the [010] axis substantially orthogonal to the [001] axis orientation The crystallographic orientation such as the orientation and the [100] axis orientation or, if necessary, the [110], [101], [011] axis orientation is generally determined.
Furthermore, the crystallographic plane {100} plane perpendicular to any crystal axis such as the [001] axis, [010] axis, and [100] axis is polished, and an accurate orientation is obtained using an X-ray orientation measuring machine or the like. And correct the deviation of the polished surface.

(3) Rough cutting (cutting into a wafer of appropriate thickness):
In the present invention, the rough cutting method is not particularly defined. For example, when the [001] direction of the single crystal ingot is the polarization direction PD, it is parallel or orthogonal to the polished surface {100} plane of the single crystal ingot. A single crystal ingot is cut using a cutting machine such as a wire saw or an inner peripheral cutting machine to obtain a plate material (wafer) having an appropriate thickness. In addition, the process of chemical-etching using an etching liquid as needed can also be included after cutting.

(4) Polishing (polishing to a predetermined thickness wafer):
The wafer is ground or polished by a lapping machine, a grinding machine such as a polishing machine, or a polishing machine to obtain a wafer having a desired thickness. In addition, the process of chemically etching using an etching liquid as needed can also be included after grinding and polishing.

(5) Manufacture of single crystal plate (single crystal element):
In the present invention, a method for producing a single crystal plate is not particularly defined.
The cutting direction of the single crystal plate varies depending on the polarization direction, the longitudinal vibration mode, or the transverse vibration mode. Hereinafter, an example of each cutting-out method will be shown for the three single crystal elements of the present invention.

(A) When using the electromechanical coupling coefficient (k ₃₁ ) of the transverse vibration mode:
As shown in FIG. 7 (a), FIG. 7 (b) and FIG. 7 (c), the [001] direction is a plane including the [100] direction and the [010] direction substantially orthogonal to the polarization direction PD. In the case of a piezoelectric single crystal element in which the end surface T is a surface that cuts the (001) plane vertically, the normal direction 1 of the end surface T is 0 ° in the [100] direction, the [010] direction, or the [110] direction. 3D of 0 ° ± 15 ° ([100] axis ± 15 °), 0 ° ± 15 ° ([010] axis ± 15 °) or 0 ° ± 5 ° ([110] axis ± 5 °), respectively. A single crystal plate having a predetermined shape is cut out from the wafer by using a precision cutting machine such as a dicing saw or a cutting saw so as to be within a corner range.

(B) [001] direction as the polarization direction PD, thereto parallel vibration mode, i.e., the piezoelectric single crystal device utilizing longitudinal vibration mode electromechanical coupling coefficient k ₃₃ of the end surface (001) If:
As shown in the piezoelectric single crystal element B of FIG. 6, the above-described precision cutting machine is used to cut and produce [001] so that the (001) plane is an end face.

(C) [110] direction as the polarization direction, it parallel to the direction vibration mode, i.e., when the piezoelectric single crystal device utilizing longitudinal vibration mode electromechanical coupling coefficient k ₃₃ of the end surface (110) plane :
As shown in the piezoelectric single crystal element C in FIG. 6, the above-described precision cutting machine is used to cut out and manufacture so that the [110] direction is the longitudinal direction of the element so that the (110) plane is the end face. .

(6) Chamfer:
As shown in the piezoelectric single crystal element B or C in FIGS. 2 and 6, when the piezoelectric single crystal element using the electromechanical coupling coefficient k ₃₃ in the longitudinal vibration mode is a rectangular parallelepiped, the longitudinal direction of the rectangular parallelepiped during polarization In order to prevent chipping from occurring on the four edges b, these edges b may be chamfered.

(7) Electrode production:
It is necessary to prepare in advance electrodes necessary for applying an applied electric field by main polarization processing or further auxiliary polarization processing.
Before the main polarization treatment, a Cr-Au film (Cr layer: thickness of about 50 mm in the first layer and Au layer in the second layer: on the opposite end surface perpendicular to the main polarization direction of the produced single crystal element material) After forming a gold film by plasma deposition or by forming a silver film by screen printing, it is baked to produce an electrode.
Further, before the auxiliary polarization treatment, electrodes are formed on two opposing surfaces perpendicular to the auxiliary polarization direction by the same method as described above.
When the main polarization process is performed after the auxiliary polarization process, or when the auxiliary polarization process is performed after the main polarization process, if the electrode used for the first polarization process remains, the subsequent polarization process becomes unstable. The electrode must be completely removed with a suitable chemical etchant and acid.

(8) Main polarization process:
If the single crystal is cut from the grown single crystal ingot, the direction of the electric dipoles in the domain consisting of a set of electric dipoles in the same direction varies in each domain in the polarization direction PD and the direction orthogonal thereto. Therefore, it does not show piezoelectricity and is in an unpolarized state.

By selecting the polarization treatment temperature and the applied electric field, which are commonly used polarization conditions, and applying the electric field to the polarization direction PD for polarization, the electric bipolars in many domains that are oriented in various directions for each domain for the first time The direction of the child can be aligned with the polarization direction PD (one direction). Accordingly, the electromechanical coupling coefficient k ₃₃ in the polarization direction PD is, for example, in the case of lead zinc niobate-lead titanate (PZN-PT) or lead magnesium niobate-lead titanate (PMN-PT). It shows a large value of 80% or more.

However, the sequence of the domain in a direction perpendicular to the polarization direction PD, which becomes a problem when the piezoelectric single crystal device using the electromechanical coupling factor k ₃₁ in the lateral vibration mode, in the above polarization treatment, can not be properly controlled. Originally, the proper selection of the cutting direction of the element in the plane orthogonal to the polarization direction PD of the cut element material and the polarization condition in the polarization direction PD, that is, only within the appropriate range of the polarization treatment temperature and the applied electric field. It is possible to control.

In the main polarization step of the present invention, it is preferable to apply a DC electric field of 350 to 1500 V / mm in the temperature range of 20 to 200 ° C. in the polarization direction PD of the cut single crystal element material. That is, the polarization is insufficient when the lower limit value of the preferred temperature range is less than 20 ° C. or when the lower limit value of the applied electric field range is less than 350 V / mm. When the upper limit value of 200 ° C is exceeded, or when the upper limit value of the applied electric field range is 1500 V / mm, hyperpolarization occurs and the piezoelectric characteristics of the piezoelectric single crystal element deteriorate. . Further, an excessive electric field may increase the strain in the crystal and cause breakage, and a crack is generated in the SHODEN single crystal element.
The polarization time is preferably adjusted according to the polarization treatment temperature and the applied electric field selected within the above preferred range. The maximum polarization time is 180 minutes.

  Alternatively, the main polarization step is performed at a temperature higher than the Curie temperature Tc of the single crystal element material, preferably 350 to 1500 V / mm in the temperature range of 180 to 300 ° C. in the polarization direction 3 of the cut single crystal element material. It is more preferable to cool to room temperature while applying a DC electric field (electric field cooling). This is because by setting the temperature to be higher than the Curie temperature Tc, the presence of the electric dipole is once eliminated, and then cooling to the Curie temperature or lower makes the direction of the electric dipole more uniform. This is because, when the temperature is lower than the Curie temperature, the electric dipole remains in part, and the polarization becomes insufficient. Further, when the lower limit value of the preferable electric field range is less than 350 V / mm, the polarization is insufficient. When the upper limit value of 500 V / mm in the preferable applied electric field range is exceeded, hyperpolarization (overpole) occurs, and the piezoelectric characteristics of the piezoelectric single crystal element are deteriorated. Further, an excessive electric field may increase strain in the crystal and cause breakage, and cracks occur in the piezoelectric single crystal element. The cooling rate is preferably a cooling rate that does not cause cracks in the element during cooling.

The Curie temperature shows, for example, the Tc line in FIGS. 8 and 9, but when the temperature is higher than that, the electric dipoles are not aligned in a disordered direction, indicating piezoelectricity or ferroelectricity. The transition temperature disappears. This is determined by the composition and structure of the substance.
In addition, as described above, the method of polarization processing of a single crystal element is not limited to the above processing. For example, after determining the crystallographic orientation, the single crystal ingot is subjected to polarization processing, and the single crystal ingot A single crystal element material having a predetermined shape may be cut out in a predetermined direction.

(9) Auxiliary polarization treatment process:
The main polarization process described above is a process of performing the main polarization of the piezoelectric single crystal element. Before or after the main polarization process is performed, the alignment state of the ferroelectric domains in the direction orthogonal to the polarization direction PD is changed. A controlled manufacturing method is also effective.
The types of electric field applied in the direction orthogonal to the above-described polarization direction PD include DC electric field, pulse electric field, AC electric field, and these steady electric fields, as well as attenuation electric fields. And the like have appropriate conditions depending on the characteristics of the individual piezoelectric single crystal elements and the desired value of the electromechanical coupling coefficient k _{31 in} the direction orthogonal to the polarization direction. These can be determined by experiments or the like. In order to obtain the effect of auxiliary polarization, the auxiliary polarization treatment temperature is 25 ° C. to a phase transition temperature (for example, the Trt line shown in FIG. 8 or the Trt line shown in FIG. 9), and the applied electric field range is 350 to 1500 V / mm is preferred. The polarization time is preferably adjusted according to the polarization treatment temperature and the applied electric field selected within the above-mentioned preferred range, but is particularly preferably 10 minutes to 2 hours.
Further, as the pulse electric field, a unipolar and bipolar pulse such as an AC triangular wave as shown in FIG. 10 can be used in addition to a rectangular wave.

  According to the present invention, a piezoelectric single crystal element comparable to a lead-based perovskite structure single crystal having no additive such as lead indium niobate and Ca can be produced. Furthermore, by suppressing the occurrence of pyrochlore phase, which is a different phase during growth of lead-based perovskite structure single crystals without additives such as lead indium niobate and Ca, and the generation of thermal cracks during cooling after the growth of the single crystals The decrease in crystal yield and wafer yield was improved. In addition, the decrease in yield of the single crystal plate due to the occurrence of chipping when the single crystal plate was cut out from the obtained wafer was also improved. As a result, it has become possible to manufacture single crystal elements at a sufficiently low cost compared to piezoelectric single crystal elements manufactured from lead-based perovskite single crystals without additives such as lead indium niobate and Ca. It has become possible to supply piezoelectric single crystal elements that can be applied to a wide range of applications that could not be achieved.

Calcium-substituted magnesium niobate [Pb (Ca) (Mg ₁ ) in which 65 mol% of lead (Pb) in lead magnesium niobate [Pb (Mg _1/3 Nb _2/3 ) O ₃ ] is replaced with 1 mol% of Ca. _{/ 3} Nb _2/3 ) O ₃ ]: 65 mol%, lead titanate [PbTiO ₃ ]: 32 mol% and lead indium niobate [Pb (In _{l / 2} Nb _{l / 2} ) O ₃ ]: 3 mol% After mixing, calcining, molding and storing in a platinum crucible of 50mmφ, heating to 1350 ° C in a vertical electric furnace to make a melt, and crucible in a temperature gradient of 20 ° C / 1cm 0.5mm / [Pb (Ca) (Mg _1/3 Nb _2/3 ) O ₃ ] _0.65 [Pb (Ca) (In _1/2 Nb _1/2 ) O ₃ ] _0.03 [Pb (Ca) TiO ₃ ] _0.32 crystal (PMN65 / PIN03-PT32 (Ca1)) was grown.

For comparison, lead magnesium niobate _{[Pb (Mg 1/3 Nb 2/3)} O 3]: 68mol% lead titanate [PbTiO _3]: 32mol% and 50mmφ platinum crucible sintered body of a solid solution consisting of It is stored inside and heated to 1330 ° C in a vertical electric furnace to form a melt, and the crucible is lowered at a constant rate of 0.5 mm / h in a temperature gradient of 20 ° C / 1 cm (solid melt) By using the Bridgman method, magnesium niobate and lead titanate [Pb (Mg _1/3 Nb _2/3 ) O ₃ ] _0.68 [PbTiO ₃ ] _0.32 (PMN68-PT32) crystals were also grown. . These crystal growths were performed 5 times each. Table 1 shows the results of examining the occurrence of pyrochlore phase and thermal cracks, crystal yield, and wafer yield for the grown crystals.

  The term “crystal yield” as used herein means the percentage (%) of the mass of a healthy single crystal part free from the pyrochlore phase and thermal cracks with respect to the mass of the charged raw material. “Wafer yield” refers to the pyrochlore phase and the heat relative to the number of wafers obtained by cutting the obtained single crystal portion in a desired orientation with a cutting tool such as a wire saw at a thickness of 0.36 mm. It means the percentage (%) of the number of healthy wafers without cracks.

  The presence or absence of the pyrochlore phase was confirmed by visually confirming the color and transparency of the single crystal ingot and the wafer. The pyrochlore phase is more transparent than the perovskite phase and can therefore be clearly distinguished. The presence or absence of thermal cracks was visually observed by a method of transmitting light to the wafer and, if necessary, spraying a dye penetrating flaw detector with a spray and developing. The number of cracks was 2-3.

  From Table 1, it can be seen that the PMN65 / PIN03-PT32 (Ca1) single crystal, which is an invention example, has a remarkably superior crystal yield and wafer yield compared to the PMN68-PT32 single crystal which is a comparative example. .

Next, the two types of wafers obtained in Example 1 were processed into rectangular plates having desired orientations on the end faces. Here, the [001] direction is the normal direction of the surface having the maximum area of the wafer, and the [100] direction and the [010] direction are the normal directions of the end faces, respectively, 13 mm long × 4 mm wide × 0.36 mm thick 50 single-crystal plates were cut out with a dicing saw for each of two types of rectangular plates. The presence or absence of chipping when dicing two types of wafers, the ratio of the number of chips generated in the total (50 sheets) and the single crystal plate yield (single crystal plate yield = 100%-chipping) Table 2 shows the occurrence ratio. The dicing process was performed at a cutting speed of 0.2 mm / s.
The presence or absence of chipping was determined to be present when the periphery of the single crystal plate was observed with a stereomicroscope and there was at least one chip of 30 μm or more.

  From Table 2, the PMN65 / PIN03-PT32 (Ca1) single crystal, which is an example of the invention, is significantly suppressed in chipping during dicing as compared with the PMN68-PT32 single crystal which is a comparative example. Recognize.

Next, in order to fabricate a piezoelectric single crystal element using the transverse vibration mode from the two types of wafers obtained in Example 1, as shown in the single crystal element A of FIG. 6, the [001] direction is 0.36 mm. A single crystal element material of 13 mm × 4 mm × 0.36 mm having dimensions of 4 mm and 13 mm in the [010] direction and the [100] direction, respectively, was cut with a dicing saw. On the upper and lower surfaces 10a and 10b, which are the (100) faces of the single crystal element material thus produced, a Cr—Au coating (Cr layer: thickness of about 50 mm in the first layer and Au layer: thickness of about 2 in the second layer) is formed by sputtering. 100 to 200 mm) is formed to produce a gold electrode, and this single crystal element material is polarized by applying a DC electric field of 700 V / mm for 1 hour in a 40 ° C. silicon oil bath, and used for piezoelectric property evaluation. A sample was prepared. Electromechanical related to the transverse vibration mode, which is the piezoelectric characteristics of the piezoelectric single crystal element made from PMN65 / PINO3-PT32 (Ca1), which is an example of the invention, and the piezoelectric single crystal element made from PMN68-PT32 single crystal, which is a comparative example Table 3 shows the measurement results of the coupling coefficient k ₃₁ and the piezoelectric strain constant d ₃₁ . For reference, the piezoelectric characteristics of piezoelectric elements made of the current mainstream piezoelectric element materials and the conventional lead zirconate titanate (Pb (Zr, Ti) O ₃ ) sintered body (PZT) Are also shown in Table 3. K ₃₁ and d ₃₁ are the impedance curve and phase of the k ₃₁ mode obtained using an impedance gain phase analyzer (HP, device number: HP4194A) for the piezoelectric single crystal element after polarization treatment. From the above, it was calculated by a known calculation formula (see Electronic Materials Industry Association Standard: EMAS-6008, 6100).

From Table 3, the piezoelectric single crystal element manufactured from the PMN65 / PINO3-PT32 (Ca1) single crystal, which is an example of the invention, is a comparative example in terms of the electromechanical coupling coefficient k ₃₁ and the piezoelectric strain constant d ₃₁ regarding the transverse vibration mode. The piezoelectric single crystal device fabricated from PMN68-PT32 single crystal maintains almost the same value, and is a conventional example of lead zirconate titanate (Pb (Zr, Ti) O ₃ ) sintered body (PZT) It can be seen that it is significantly superior to the piezoelectric element fabricated in (1).

Next, in order to grasp the relationship between the normal direction 1 of the end face T of the piezoelectric single crystal element utilizing the transverse vibration mode and the crystallographic orientation, PMN65 / PIN03− With the [001] direction of the PT32 (Ca1) single crystal plate and the PMN68-PT32 single crystal plate as the polarization direction, the plane of the maximum area of the 13 mm × 4 mm × 0.36 mm piezoelectric single crystal element is orthogonal to the [001] direction (001) The normal direction 1 of the end face T of 4 mm × 0.36 mm used in the transverse vibration mode is 0 °, the [100] direction is 0 °, the [110] direction is 45 °, and the [010] direction is 90 °. By changing every 5 ° in the range of 0 ° to 90 °, various single crystal element materials cut out by using a dicing saw were produced, and the upper surfaces of the produced single crystal element materials were the (001) faces facing each other. A gold electrode was produced on the lower surface in the same manner as in Example 3, and this single crystal element material was used. It was polarized under 3 the same way.
With respect to the piezoelectric single crystal element after the polarization treatment, the electromechanical coupling coefficient k ₃₁ related to the transverse vibration mode was measured in the same manner as in Example 3. Table 4 shows the measurement results. Here, the fact that the normal direction 1 of the end face T is selected from the range of 0 ° to 90 ° with respect to the [100] direction is that information on all directions in the {100} plane is obtained from the symmetry of the cubic crystal. This is because the angle range is necessary and sufficient to obtain the above. For reference, the electromechanical coupling coefficient k ₃₁ related to the transverse vibration mode of a piezoelectric element made of a conventional lead zirconate titanate (Pb (Zr, Ti) O ₃ ) sintered body (PZT) is shown. This is also shown in Table 4. Since PZT is a sintered body and does not have anisotropy associated with the crystal orientation as in the piezoelectric single crystal shown here, the electromechanical coupling coefficient k ₃₁ regarding the transverse vibration mode is the normal line of the end face T. Regardless of direction 1, it is the same value over all crystal orientations.

From Table 4, the preferred orientation of the normal direction 1 of the end face T of the piezoelectric single crystal element using the transverse vibration mode is 0 ° to the normal direction of the end face when the [100] direction is 0 °. 15 ° range (equivalent to 0 ° ± 15 ° range from the above-mentioned symmetry and an angle within the range of [100] axis ± 15 °) and 45 ± 5 ° range (± 45 from the above-mentioned symmetry) It can be seen that the range is equivalent to the range of ± 5 °, that is, the range within which the [110] axis is within ± 5 °. Even when the [010] direction is set to an angle of 0 °, the preferred normal direction 1 orientation of the end face of the piezoelectric single crystal element T using the transverse vibration mode is 0 ° to 15 ° in the normal direction of the end face. ° (equivalent to the range of 0 ° ± 15 ° from the above-mentioned symmetry and an angle within [010] axis ± 15 °) and 45 ± 5 ° (range of ± 45 ± 5 ° from the above-mentioned symmetry) It is also confirmed that the angle is within the range of [110] axis ± 5 °.
In the above embodiment, the [001] direction of the single crystal plate is the polarization direction, and the surface of the maximum area of the piezoelectric single crystal element of 13 mm × 4 mm × 0.36 mm is in the (001) plane orthogonal to the [001] direction. Although a suitable orientation was confirmed, even when the normal direction 1 of the end face T in the solid angle shown in FIGS. 7 (a) to (c) is in the range of 0 ° ± 15 ° and 45 ° ± 5 °, good k It was confirmed that ₃₁ was obtained.

  The PMN65 / PIN03-PT32 (Ca1) single crystal and the PMN68-PT32 single crystal each have a perovskite structure, and [310], between the [100] direction and the [010] direction in the (001) plane. It includes low index crystal axes such as [210] and [320].

When the piezoelectric single crystal element manufactured using the PMN65 / PIN03-PT32 (Ca1) single crystal and the PMN68-PT32 single crystal is in the preferred angle range, the direction of the low index crystal axis is lateral to the piezoelectric single crystal element. Since the end face T using the directional vibration mode has a sufficiently large angular difference from the normal direction 1 of the end face T, the dispersion in the low index crystal axis direction is suppressed. It is considered that the mechanical coupling coefficient k ₃₁ can be increased.

On the other hand, when the preferred orientation of the end face of the piezoelectric single crystal element using the transverse vibration mode is outside the angular range, the influence of low index crystal axes such as [310], [210] and [320] is large. Since the transverse vibration is dispersed in the normal direction 1 of the end face T and the low index crystal axis direction, the electromechanical coupling coefficient k ₃₁ of the transverse vibration mode of the end face is reduced and the transverse direction is reduced. It is considered that the piezoelectric single crystal element utilizing the vibration mode is not suitable.

In addition, the piezoelectric single crystal element fabricated from PMN65 / PIN03-PT32 (Ca1) single crystal has an electromechanical coupling coefficient k ₃₁ related to the transverse vibration mode substantially equal to that of the piezoelectric single crystal element fabricated from PMN68-PT32 single crystal. Thus, it was found to be much better than a piezoelectric element made of a sintered body of lead zirconate titanate (Pb (Zr, Ti) O ₃ ) (PZT).

Next, in order to fabricate a piezoelectric single crystal element using a longitudinal vibration mode using a PMN65 / PINO3-PT32 (Ca1) single crystal plate, 10 mm in the [001] direction as shown in the single crystal element B of FIG. A 4 mm × 4 mm × 10 mm single crystal cuboid having a length of 4 mm in both the [010] direction and the [100] direction was cut with a wire saw. Gold electrodes are produced on the upper and lower surfaces, which are the (001) faces, of this single crystal cuboid in the same manner as in Example 3, and this single crystal element material is placed in a [001] direction in a 40 ° C. silicon oil bath. Was polarized by applying a DC electric field of 0.7 kV / mm for 1 hour to prepare a sample for piezoelectric property evaluation.
For comparison, a similar sample was cut out from PMN68-PT32 single crystal and polarized under the same conditions.
Electric machine related to longitudinal vibration mode, which is the piezoelectric characteristic of the piezoelectric single crystal element manufactured from PMN65 / PINO3-PT32 (Ca1), which is an example of the invention, and the piezoelectric single crystal element manufactured from PMN68-PT32 single crystal, which is a comparative example Table 5 shows the measurement results of the coupling coefficient k ₃₃ and the piezoelectric strain constant d ₃₃ . For reference, the piezoelectric characteristics of piezoelectric elements made of the current mainstream piezoelectric element materials and the conventional lead zirconate titanate (Pb (Zr, Ti) O ₃ ) sintered body (PZT) Are also shown in Table 5.
In addition, the piezoelectric single crystal element k ₃₃ after the polarization treatment is obtained by using a known calculation formula (Electronic Material Industries Association Standard: EMAS-6008, using an impedance gain phase analyzer (manufactured by HP, apparatus number: HP4194A), 6100). The piezoelectric strain constant (d ₃₃ ) was directly measured using a d ₃₃ meter (manufactured by INSTITUTE of ACOUSTICS ACADEMIA SINICA: PIEZO d ₃₃ METER Model ZJ-30) made in China.

From Table 5, the piezoelectric single crystal element produced from the PMN65 / PINO3-PT32 (Ca1) single crystal, which is an example of the invention, has an electromechanical coupling coefficient (k ₃₃ ) and a piezoelectric strain constant (d ₃₃ ) related to the longitudinal vibration mode. The piezoelectric single crystal element made from the PMN68-PT32 single crystal, which is a comparative example, maintains almost the same value and is sintered with lead zirconate titanate (Pb (Zr, Ti) O ₃ ), which is a conventional example. It can be seen that it is far superior to the piezoelectric element fabricated with the body (PZT).

  Next, in order to fabricate a piezoelectric single crystal element using a longitudinal vibration mode produced using a PMN65 / PINO3-PT32 (Ca1) single crystal plate, as shown in the piezoelectric single crystal element B of FIG. 6, [001] A 1 mm × 1 mm × 20 mm PMN65 / PIN03-PT32 (Ca1) single crystal cuboid having a length of 20 mm in the direction and 1 mm in both the [010] direction and the [100] direction was cut by a wire saw. Gold electrodes were produced on the upper and lower surfaces, which are the (001) faces of this single crystal cuboid, in the same manner as in Example 3. A piezoelectric single crystal element was obtained by polarization by applying a DC electric field of kV / mm for 1 hour. Using 400 such piezoelectric single crystal elements, these are arranged in a jig at intervals of 1 mm in parallel so that the end faces are located in the same plane as shown in FIG. 1, and the gap is filled with epoxy resin. 20 × 20 1-3 composite piezoelectric elements were produced.

  On the other hand, PMN68-PT32 single crystal was processed in the same manner, but many cracks and chipping occurred, and the necessary 400 piezoelectric single crystal elements could not be obtained, making it impossible to produce 1-3 composite piezoelectric elements. .

Piezoelectric properties (k ₃₃ , d ₃₃ ) of the produced 1-3 composite piezoelectric element made of PMN65 / PINO3-PT32 (Ca1) single crystal were measured by the same method as in Example 5, and the conventional lead zirconate titanate ( Comparison was made with the piezoelectric characteristics of an equivalent 1-3 composite piezoelectric element made of Pb (Zr, Ti) O ₃ ) sintered body (PZT).
The results are shown in Table 6.

As a result, as in the comparison between the piezoelectric single crystal elements alone, the 1-3 composite piezoelectric element manufactured from the PMN65 / PINO3-PT32 (Ca1) single crystal has a relative dielectric constant ε ₃₃ ^T and d _h related to the longitudinal vibration mode. However, it is confirmed that it is far superior to the 1-3 composite piezoelectric element made from PZT. Therefore, the PMN65 / PIN03-PT32 (Ca1) single crystal has a lower yield than the PMN68-PT32 single crystal. 1-3 composite piezoelectric elements that cannot be manufactured at reasonable prices can be manufactured at low cost, and the piezoelectric properties such as electromechanical coupling coefficient and piezoelectric strain constant are the mainstream of current piezoelectric element materials, lead zirconate titanate (Pb It was found that it was markedly superior to piezoelectric elements made of (Zr, Ti) O ₃ ) sintered body (PZT).
The relative dielectric constant ε ₃₃ ^T was obtained for the piezoelectric single crystal element after the polarization treatment using an impedance analyzer (manufactured by YHP, device number: YHP4192A LF IMPEDANCE ANALYZER). The piezoelectric strain constant d _h was determined by a known predetermined calculation formula (d _h = d ₃₃ + 2d ₃₁ ).

In all of Examples 1 to 6 described above, [Pb (Ca) (Mg _1/3 Nb _2/3 ) O ₃ ] _0.65 [Pb (Ca) (In _1/2 Nb _1/2 ) O ₃ ] _0.03 [Pb (Ca) TiO ₃ ] _0.32 crystal (PMN65 / PIN03-PT32 (Ca1)) has been explained, but lead magnesium niobate (PMN (Ca)), lead indium niobate (PIN (Ca)), titanium Crystals with various amounts of lead oxide (PT (Ca)) and calcium (Ca) added, and crystals using lead zinc niobate PZN (Ca) instead of lead magnesium niobate (PMN (Ca)) Also in this case, the situation of the pyrochlore phase, the crystal yield, the presence or absence of thermal cracks, and the wafer yield were confirmed in the same manner as in Example 1. The results are shown in Table 7.

  As a result, it was found that in both cases, the crystal yield and wafer yield were high and the productivity was high. Also, it was confirmed that the piezoelectric element using these crystals has the same characteristics as [PMN65 / PIN03-PT32 (Cal)].

Next, [Pb (Ca) (Mg _1/3 Nb _2/3 ) 0 ₃ ] _0.65 [Pb (Ca) (In _1/2 Nb _1/2 0 ₃ )] _0.03 [Pb (Ca) TiO ₃ ] _0.32 0.5 ppm to 5 mass% of one or more elements selected from the group consisting of Mn, Cr, Sb, W, Al, La, Li, and Ta in a solid solution of crystals (PMN65 / PINO3-PT32 (Cal)) Further, for the added composition, a device was produced by the same manufacturing method as in Example 3, and the electromechanical coupling coefficient k ₃₁ was examined under the same test conditions as PMN65 / PINO3-PT32 (Cal). As described above, in each case, a high electromechanical coupling coefficient k ₃₁ equivalent to that of PMN68-PT32 of the comparative example was obtained. In particular, the addition of Mn and Cr, the mechanical quality factor Q _m, and significantly improved 65.0 from from 120.0 to 150.0, Sb, W, La, relative dielectric constant epsilon _r by the addition of Ta is from 3500 4300-4700 and improved significantly. Incidentally, the mechanical quality factor Q _m is the impedance gain Fueizu analyzer (HP Co., device number: HP4194A): (refer to EMAS-6008,6100 Electronic Materials Manufacturers Association Standard) known equation using the Calculated. In addition, the relative dielectric constant ε _r was determined using an impedance analyzer (manufactured by HP, device number: HP4192A) in accordance with the standards of the Electronic Materials Industries Association (see EMAS-6008.6100).

Next, a preferred polarization processing method for manufacturing a piezoelectric single crystal element will be described using Example 9. Various primary polarization processing conditions results of measurement of the piezoelectric single crystal device of the electromechanical coupling factor k ₃₁ in the lateral vibration mode obtained in Example 3 was prepared in shown in Table 9. The manufacturing method, element dimensions, and test conditions of the piezoelectric single crystal element other than the main polarization treatment conditions were the same as in Example 3.

Example 1 PMN65 / PINO3-PT32 (Cal) element manufactured by the same method as in Example 3 and a comparative example PMN68-PT32 element, the polarization temperature of the piezoelectric single crystal element suitable for use in the transverse mode The applied electric field was 700 V / mm within the range of the present invention, and the polarization time was adjusted according to the polarization treatment temperature. The results are shown in Nos. 1 to 5 in Table 9. As shown in No. 1 of Table 9, when the polarization treatment temperature is less than 20 ° C., the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (transverse vibration mode) is PMN65 / PINO3−PT32 ( Cal) element and the PMN68-PT32 element of the comparative example were 25% and 20%, respectively, and the characteristics of the element for the transverse vibration mode were insufficient. In addition, when the polarization treatment temperature was 15 ° C. and the application time was shorter than 180 minutes, only a lower electromechanical coupling coefficient k ₃₁ was obtained. This is considered to be because the polarization is insufficient when the polarization treatment temperature is less than 20 ° C. On the other hand, when the polarization treatment temperature exceeds 200 ° C. as shown in No. 5 of Table 9, the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (lateral vibration mode) is PMN65 / PINO3−PT32 of the invention example. The (Cal) element and the comparative PMN68-PT32 element were 32% and 30%, respectively. In addition, in the case where the application time exceeds 30 minutes at this polarization treatment temperature (210 ° C.), there are many examples in which cracks are generated in the piezoelectric single crystal element during application or immediately after completion of application.

 This is presumably because hyperpolarization (overpole) occurs under these conditions, and the electrical characteristics of the piezoelectric single crystal element deteriorate. Further, the occurrence of cracks in the piezoelectric single crystal element is considered to be due to an increase in strain in the crystal due to an excessive electric field, resulting in breakage.

The polarization treatment temperature of the piezoelectric single crystal element manufactured by the same method as in Example 3 and suitable for use in the transverse mode is set to 40 ° C. within the range of the present invention, the applied electric field is 300 to 1600 V / mm, and the polarization time is the applied electric field. Adjusted accordingly. The results are shown in Nos. 6 to 10 in Table 9. As shown in No. 6 of Table 9, when the applied electric field is less than 350 V / mm, the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (transverse vibration mode) is PMN65 / PINO3−PT32 (Cal ) The element and the PMN68-PT32 element of the comparative example were 30% and 28%, respectively, and the characteristics of the element for the transverse vibration mode were insufficient. In addition, at an applied electric field of 300 V / mm and shorter than 180 minutes, both the PMN65 / PINO3-PT32 (Cal) element of the inventive example and the PMN68-PT32 element of the comparative example have a lower electromechanical coupling coefficient k _31. Only obtained. This is presumably because the polarization is insufficient when the applied electric field is less than 350 V / mm. On the other hand, when the applied electric field exceeds 1500 V / mm as shown in No. 10 of Table 9, the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (lateral vibration mode) is PMN65 / PINO3−PT32 of the invention example. The (Cal) element and the PMN68-PT32 element of the comparative example were 32% and 30%, respectively. In addition, when the applied electric field (1600 V / mm) was applied for more than 30 minutes, there were many examples in which cracks occurred in the piezoelectric single crystal element during or immediately after the application.

  This is presumably because hyperpolarization (overpole) occurs under these conditions, and the piezoelectric characteristics of the piezoelectric single crystal element deteriorate. Further, the occurrence of cracks in the piezoelectric single crystal element is considered to be due to an increase in strain in the crystal due to an excessive electric field, resulting in breakage.

  Furthermore, a crystal suitable for use in the transverse vibration mode of the PMN65 / PINO3-PT32 (Cal) element of the invention example and the PMN68-PT32 element of the comparative example is 200 ° C. above the Curie temperature Tc shown in FIG. Table 9 shows the results of applying a DC electric field of 300 to 1600 V / mm in silicon oil and adjusting the polarization time according to the applied electric field. Shown in 11-15.

No. in Table 9 When the applied electric field is less than 350 V / mm as in 11, the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (transverse vibration mode) is the same as that of the PMN65 / PINO3-PT32 (Cal) element of the invention example and the comparative example. PMN68-PT32 elements were 35% and 32%, respectively, which was insufficient as the characteristics of the element for the transverse vibration mode. In addition, at an applied electric field of 300 V / mm and an application time shorter than 100 minutes, both the PMN65 / PINO3-PT32 (Cal) element of the inventive example and the PMN68-PT32 element of the comparative example have a lower electromechanical coupling coefficient k _31. Only obtained. This is presumably because the polarization is insufficient when the applied electric field is less than 350 V / mm. On the other hand, when the applied electric field exceeds 1500 V / mm as shown in No. 15 of Table 9, the electromechanical coupling coefficient k ₃₁ in the direction orthogonal to the polarization direction (lateral vibration mode) is PMN65 / PINO3−PT32 of the invention example. The (Cal) element and the PMN68-PT32 element of the comparative example were 40% and 38%, respectively. In addition, when the applied electric field was 1600 V / mm and the application time exceeded 30 minutes, there were many examples in which cracks occurred in the piezoelectric single crystal element during application or immediately after completion of application.

As described above, the PMN65 / PINO3-PT32 (Cal) element of the invention example and the PMN68-PT32 element of the comparative example are both in the direction of the appropriate polarization condition (in the transverse vibration mode). ) Electromechanical coupling coefficient k ₃₁ value was obtained.

  The above description shows only a part of the embodiments of the present invention, and various modifications can be made within the scope of the claims.

  According to the present invention, a piezoelectric single crystal element comparable to a lead-based perovskite structure single crystal having no additive such as lead indium niobate and Ca can be produced. Furthermore, the appearance of a pyrochlore phase, which is a different phase during the growth of lead-based perovskite structure single crystals without additives such as lead indium niobate and Ca, and the crystal yield due to the occurrence of thermal cracks during cooling after the growth of the single crystal The reduction in wafer yield was improved. In addition, the decrease in the yield of the single crystal plate due to the occurrence of chipping for cutting the single crystal plate from the obtained wafer was also improved. As a result, it has become possible to manufacture at a sufficiently low cost compared to a piezoelectric single crystal element manufactured from a lead-based perovskite structure single crystal having no additive such as lead indium niobate and Ca. It has become possible to supply piezoelectric single crystal elements that can be adapted to application fields.

It is a perspective view which shows an example of 1-3 composite piezoelectric elements. Is a diagram illustrating an example of the orientation and shape of the piezoelectric single crystal device utilizing longitudinal vibration mode electromechanical coupling coefficient k _33. It is a diagram illustrating an example of the orientation and shape of the piezoelectric single crystal device utilizing an electromechanical coupling factor k ₃₁ in the direction 1 that is substantially orthogonal to the polarization direction 3 (lateral vibration mode). It is a view showing the shape of the end face of the piezoelectric single crystal device using the electromechanical coupling factor k ₃₁ in the direction 1 that is substantially orthogonal to the polarization direction 3 (or PD) (lateral vibration mode). It is a schematic perspective view of a perovskite crystal structure (RMO _3). It is a figure which shows the shape and positional relationship of the piezoelectric single crystal element of this invention. (A) shows a piezoelectric unit that uses the electromechanical coupling coefficient k ₃₁ in the [100] direction (lateral vibration mode) substantially orthogonal to the [001] direction, with the polarization direction 3 (or PD) as the [001] direction. It is a figure which shows the normal line direction 1 of the suitable end surface T of a crystal element, (b) makes the polarization direction 3 (or PD) the [001] direction, and the [010] direction substantially orthogonal to this [001] direction is a diagram showing the normal direction 1 of the preferred end face T of the piezoelectric single crystal device using the electromechanical coupling factor k ₃₁ in the (lateral vibration mode), the (c), the polarization direction 3 (or PD) [ 001] direction, and shows the normal direction 1 of the preferred end face T of the piezoelectric single crystal element using the electromechanical coupling coefficient k ₃₁ in the [110] direction (lateral vibration mode) substantially orthogonal to the [001] direction. FIG. It is a phase diagram of PMN-PT (PMNT). It is a phase diagram of PZN-PT (PZNT). It is a wave form diagram of a bipolar triangular wave pulse.

Explanation of symbols

1 lateral direction normal to the device end face T to utilize electromechanical coupling factor k ₃₁ vibration mode (lateral vibration direction)
2 Element end face depth direction 3 (or PD) Polarization direction (longitudinal vibration direction)
Parallelepiped piezoelectric single-crystal device using an electromechanical coupling factor k ₃₃ in the A lateral electromechanical coupling factor k ₃₁ plate-like body of piezoelectric single crystal device B utilize vibration modes, C the polarization direction (longitudinal vibration mode) T End face V of cut single crystal element material DC voltage a Horizontal dimension b of single crystal element c Vertical direction (thickness direction) dimension of single crystal element c (Depth (direction 2)) dimension c ′ of single crystal element Convex end face c ″ of crystal element Concave end face of single crystal element

Claims (9)

In a piezoelectric single crystal having a composite perovskite structure, lead magnesium niobate [Pb (Mg _{l / 3} Nb _2/3 ) O ₃ ] or lead zinc niobate [Pb (Zn _{l / 3} Nb _2/3 ) O ₃ ]: In a composition containing 35 to 98 mol%, and lead titanate [PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to 30 mol% A piezoelectric single crystal in which 0.05 to 10 mol% of lead in the composition is replaced with calcium. In a piezoelectric single crystal having a composite perovskite structure, lead magnesium niobate [Pb (Mg _{l / 3} Nb _2/3 ) O ₃ ] or lead zinc niobate [Pb (Zn _{l / 3} Nb _2/3 ) O ₃ ]: In a composition containing 35 to 98 mol%, and lead titanate [PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to 30 mol% In the composition, 0.05 to 10 mol% of lead in the composition is replaced with calcium, and one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta are added in total. Piezoelectric single crystal containing 5 mol% or less. The [001] direction of the ingot of the piezoelectric single crystal according to claim 1 or 2 is a polarization direction, and a [100] direction, a [010] direction or a [110] direction substantially orthogonal thereto is a normal line of an end face of the single crystal element. A piezoelectric single crystal element using an electromechanical coupling coefficient (k ₃₁ ) of a transverse vibration mode as a direction,
The normal direction of the end face is a piezoelectric single crystal element having a solid angle range of [100] axis ± 15 °, [010] axis ± 15 °, or [110] axis ± 5 °. 3. An electromechanical coupling coefficient of a vibration mode in a direction parallel to the [001] direction of the piezoelectric single crystal ingot according to claim 1 or 2, that is, a longitudinal vibration mode having an (001) plane as an end face. A piezoelectric single crystal element using (k ₃₃ ),
When the length or diameter of the minimum side of the element end face perpendicular to the polarization direction is a and the element length in the direction parallel to the polarization direction is b, a and b satisfy the relational expression b / a ≧ 2.5. Piezoelectric single crystal element. The electromechanical coupling coefficient of a vibration mode in a direction parallel to the [110] direction of the ingot of the piezoelectric single crystal according to claim 1 or 2, ie, a longitudinal vibration mode having an (110) plane as an end face. A piezoelectric single crystal element using (k ₃₃ ),
When the length or diameter of the minimum side of the element end face perpendicular to the polarization direction is a and the element length in the direction parallel to the polarization direction is b, a and b satisfy the relational expression b / a ≧ 2.5. Piezoelectric single crystal element.   A 1-3 composite piezoelectric element formed by arranging a plurality of piezoelectric single crystal elements according to claim 4 or 5 so that element end faces perpendicular to the polarization direction are located in the same plane.   Before and after the single crystal element material having a predetermined shape is cut out from the piezoelectric single crystal ingot according to claim 1 or 2 in a predetermined direction, the single crystal ingot or the cut single crystal element material has a thickness of 20 to 200 in a direction to be polarized. Apply a DC electric field of 350 to 1500 V / mm in the temperature range of ℃, or cool to room temperature while applying a DC electric field of 350 to 1500 V / mm at a temperature higher than the Curie temperature (Tc) of the single crystal element material 6. The method for manufacturing a piezoelectric single crystal element according to claim 3, further comprising a step of polarizing a single crystal ingot or a single crystal element material. Magnesium lead niobate [Pb (Mg _{l / 3} Nb _2/3 ) O ₃ ] or lead zinc niobate [Pb (Zn _{l / 3} Nb _2/3 ) O ₃ ]: 35 to 98 mol%, and lead titanate [ PbTiO ₃ ]: 0.1 to 64.9 mol%, lead indium niobate [Pb (In _{l / 2} Nb _1/2 ) O ₃ ]: 0.05 to 30 mol%, the composition containing lead in the composition Before and after cutting out a single crystal element material of a predetermined shape in a predetermined direction from a piezoelectric single crystal ingot in which 0.05 to 10 mol% is replaced with calcium, the single crystal ingot or the cut out single crystal element material in the direction to be polarized, Apply a DC electric field of 350-1500 V / mm in the temperature range of 20-200 ° C. or room temperature while applying a DC electric field of 350-1500 V / mm at a temperature higher than the Curie temperature (Tc) of the single crystal element material Single crystal element having step of polarizing single crystal ingot or single crystal element material by cooling to Manufacturing method.   9. The ingot of the piezoelectric single crystal according to claim 8, further comprising one or more elements selected from Mn, Cr, Sb, W, Al, La, Li and Ta in a total amount of 5 mol% or less. A method for manufacturing a piezoelectric single crystal element.

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