Method for manufacturing perovskite-type single crystal, perovskite-type single crystal, piezoelectric element, ultrasonic motor, optical device, vibration device, dust removal device, imaging device, ultrasonic probe, ultrasonic diagnostic device, ultrasonic diagnostic system, and electronic device

Abstract

To provide a single crystal having a large electromechanical coupling coefficient and a large coercive electric field when used as a piezoelectric element, and a method for manufacturing the same.SOLUTION: A method for manufacturing a perovskite-type single crystal, the method comprising the steps of (1) firing a raw material containing an acceptor in an air atmosphere to obtain a first perovskite-type single crystal, (2) firing the first single crystal in a reducing atmosphere, and (3) firing the single crystal obtained in step (2) in an air atmosphere, thereby obtaining a perovskite-type single crystal having a higher coercive electric field value than the first single crystal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a perovskite single crystal and the perovskite single crystal, and also to a piezoelectric element, an ultrasonic motor, an optical device, a vibration device, a dust removal device, an imaging device, an ultrasonic probe, an ultrasonic diagnostic device, an ultrasonic diagnostic system, and an electronic device that use the single crystal. [Background technology]

[0002] In recent years, piezoelectric devices have become more sophisticated and smaller, requiring piezoelectric materials to have higher piezoelectric performance than ever before. One known method for improving the piezoelectric performance of piezoelectric materials is to align the crystal orientation within the piezoelectric material to produce a single crystal. Single-crystal piezoelectric materials can achieve a high electromechanical coupling coefficient, resulting in improved piezoelectric performance.

[0003] For example, Patent Document 1 discloses a solid-phase method for single-crystallizing piezoelectric materials such as barium titanate, in which a seed single crystal is bonded to a matrix and heat-treated to cause the growth of abnormal grains in which only a single crystal grain grows, and then the abnormal grains are cut out to obtain single crystals.

[0004] However, although the piezoelectric material obtained by the manufacturing method described in Patent Document 1 has an improved electromechanical coupling coefficient due to single crystallization, its coercive field, which represents the magnitude of the external electric field at which polarization becomes zero, decreases. When a piezoelectric material with a small coercive field is driven at a high voltage, it loses its piezoelectric performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3507821 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, merely crystallizing a piezoelectric material by conventional techniques can provide high piezoelectric properties, but the coercive field is reduced.

[0007] The present invention has been made to solve these problems, and one of its objects is to provide a method for producing a single crystal that has a large electromechanical coupling coefficient and a large coercive field when made into a piezoelectric element. Another object of the present invention is to provide an ultrasonic motor, optical equipment, vibration device, dust removal device, imaging device, ultrasonic probe, ultrasonic diagnostic device, ultrasonic diagnostic system, and electronic device that use a piezoelectric element that has a large electromechanical coupling coefficient and a large coercive field. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a method for producing a perovskite-type single crystal, which is characterized by sequentially carrying out step (1) of firing a raw material containing an acceptor in an air atmosphere to obtain a first perovskite-type single crystal, step (2) having a step of firing the first single crystal in a reducing atmosphere, and step (3) having a step of firing the single crystal obtained in step (2) in an air atmosphere, thereby obtaining a single crystal having a higher coercive field value than the first single crystal.

[0009] The present invention also provides a single crystal containing Mn and an oxide having a perovskite structure containing Ba, Ti, and Zr, wherein x, which is the molar ratio of Zr to the sum of the Ti and Zr, is 0.02≦x≦0.13, and the content of the Mn is 0.04 parts by mass or more and 0.36 parts by mass or less, calculated as the metal, per 100 parts by mass of the oxide. The single crystal may also contain Bi, and the content of Bi is 0 parts by mass or more and 0.20 parts by mass or less, calculated as the metal, per 100 parts by mass of the oxide. The single crystal has an electromechanical coupling coefficient k33 of 80% or more at 25°C and a coercive field of 2.5 kV / cm or more.

[0010] The present invention also provides a piezoelectric element having a plurality of electrodes and the above single crystal. The present invention also provides an ultrasonic motor having a vibrating body on which the above-mentioned piezoelectric element is arranged, and a moving body in contact with the vibrating body. The present invention also provides an optical device having the above ultrasonic motor in a drive section. The present invention also provides a vibration device having a vibrating body in which the above-described piezoelectric element is arranged on a vibration plate. The present invention also provides a dust removing device having the above vibration device in a vibration section. The present invention also provides an imaging device having the above-described dust removal device and an imaging element unit, in which the diaphragm of the above-described dust removal device is provided on the light receiving surface side of the imaging element unit. The present invention also provides an ultrasonic probe having the above-described piezoelectric element, which transmits and receives ultrasonic waves by means of the piezoelectric element. The present invention also provides an ultrasonic diagnostic apparatus having the above ultrasonic probe and an image output unit. The present invention also provides an ultrasound diagnostic system having the above ultrasound probe, a transmitter that transmits a signal output from the above ultrasound probe, and a receiver that receives the signal transmitted from the transmitter. The present invention also provides an electronic device equipped with a piezoelectric acoustic component having the above-described piezoelectric element. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a method for producing a single crystal having a high electromechanical coupling coefficient and a high coercive field, which could not be produced by conventional methods, and the single crystal. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 5]FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 6] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 7] FIG. 1 is a schematic diagram for explaining a first embodiment of the present invention. [Figure 8] 1 is a schematic diagram showing an embodiment of the configuration of a piezoelectric element of the present invention. [Figure 9] 1 is a schematic diagram showing an embodiment of the configuration of an ultrasonic motor of the present invention. [Figure 10A] 1 is a schematic diagram illustrating an embodiment of an optical instrument according to the present invention. [Figure 10B] FIG. 1 is a schematic diagram showing another embodiment of the optical instrument of the present invention. [Figure 11] 1 is a schematic diagram illustrating an embodiment of an optical instrument according to the present invention. [Figure 12A] 1 is a schematic diagram showing an embodiment in which a vibration device of the present invention is used as a dust removal device. [Figure 12B] FIG. 10 is a schematic diagram showing another embodiment in which the vibration device of the present invention is used as a dust removal device. [Figure 13A] 2 is a schematic diagram illustrating an example of the configuration of a piezoelectric element in the dust removing device of the present invention. FIG. [Figure 13B] 10 is a schematic diagram showing another example of the configuration of a piezoelectric element in the dust removing device of the present invention. FIG. [Figure 13C] 10 is a schematic diagram showing another example of the configuration of a piezoelectric element in the dust removing device of the present invention. FIG. [Figure 14A] 1 is a schematic diagram illustrating an example of the vibration principle of a dust removing device according to the present invention. [Figure 14B] 5A and 5B are schematic diagrams illustrating another example of the vibration principle of the dust removing device of the present invention. [Figure 15] 1 is a schematic diagram illustrating an embodiment of an imaging device of the present invention. [Figure 16] 1 is a schematic diagram illustrating an embodiment of an imaging device of the present invention. [Figure 17] 1 is a schematic diagram illustrating an embodiment of an ultrasonic probe of the present invention. [Figure 18]1 is a schematic diagram showing an embodiment of an ultrasonic diagnostic apparatus of the present invention. [Figure 19] 1 is a schematic diagram showing an embodiment of an ultrasound diagnostic system of the present invention. [Figure 20] 1 is a schematic diagram showing an embodiment of an ultrasound diagnostic system of the present invention. [Figure 21] 1 is a schematic diagram illustrating an embodiment of an electronic device of the present invention. [Figure 22] FIG. 1 is a schematic diagram for explaining one embodiment of the pole figure measurement of X-ray diffraction of a single crystal according to the present invention. [Figure 23] FIG. 1 is a schematic diagram for explaining one embodiment of the pole figure measurement of X-ray diffraction of a single crystal according to the present invention. [Figure 24] FIG. 1 is a schematic diagram for explaining one embodiment of a PE hysteresis curve of a single crystal piezoelectric element of the present invention. [Figure 25] FIG. 2 is a schematic diagram for explaining one embodiment of the temperature dependence of the piezoelectric constant of a single crystal piezoelectric element of the present invention. [Figure 26] FIG. 2 is a schematic diagram for explaining the temperature dependence of the relative dielectric constant of a single crystal piezoelectric element according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described. The present invention provides a method for producing a perovskite-type single crystal having both a high electromechanical coupling coefficient and a high coercive field, and a perovskite-type single crystal obtained thereby. Furthermore, the perovskite single crystal of the present invention can be used as a piezoelectric element in a variety of applications, such as electronic devices such as semiconductors, light-emitting elements, optical elements, energy conversion elements, and sensors.

[0014] First Embodiment The first embodiment relates to a method for producing a perovskite-type single crystal. The method for producing a perovskite single crystal of the present invention is characterized by having a higher coercive field value than the first single crystal, by sequentially going through step (1) of obtaining a first perovskite single crystal by firing a raw material containing an acceptor in an air atmosphere, step (2) having a step of firing the first single crystal in a reducing atmosphere, and step (3) having a step of firing the single crystal obtained in step (2) in an air atmosphere. Below, each item will be explained together with an explanation of basic matters for understanding the invention.

[0015] [Explanation 1 for understanding the invention] (single crystal) A single crystal is a material consisting of a single crystal grain, and the crystal axis, which is the direction of the atomic arrangement, is the same throughout the crystal grain. However, the single crystal of the present invention may contain lattice defects such as dislocations, vacancies, gaps, heterophases, amorphous phases, or organic matter within the single crystal. It may also contain domain structures that arise due to differences in the crystal system caused by phase transitions or differences in the direction of spontaneous polarization.

[0016] (Perovskite type) Perovskite-type oxides refer to the ideally cubic perovskite structure (also called perovskite structure), as described in the Iwanami Dictionary of Physics and Chemistry, 5th Edition (Iwanami Shoten, February 20, 1998). Perovskite-type oxides are generally expressed by the chemical formula ABO3. The molar ratio of the A-site and B-site elements to the O-site is expressed as 1:3. However, even if some crystals contain oxygen vacancies or the element ratio is slightly off, the oxide can still be considered a perovskite-type oxide as long as it has a perovskite-type main phase. Furthermore, if the A-, B-, and O-site elements are slightly shifted from their respective symmetrical positions in the unit lattice, the perovskite-type unit lattice will be distorted, resulting in a tetragonal, rhombohedral, or orthorhombic crystal system.

[0017] The perovskite single crystal of the present invention is made of a perovskite oxide, and the crystal system of the single crystal can be not only cubic but also tetragonal, rhombohedral, or orthorhombic depending on the single or multiple elements that make up A and B. Whether an oxide is perovskite and what its crystal system is can be determined by structural analysis using, for example, X-ray diffraction or electron diffraction. In this case, the sample may be powdered before measurement, if necessary. A specific method for producing the perovskite single crystal of the present invention will be described below.

[0018] (Step of Obtaining a First Single Crystal) The process for obtaining the first single crystal may be any of liquid phase methods such as the Czochralski method, the Bridgman method, the floating zone method, and the flux method; solid phase methods such as the solid-phase reaction method and the sol-gel method; and gas phase methods such as the sublimation method and the chemical vapor deposition method, as long as the single crystal can be produced in an air atmosphere. The method for producing a single crystal of the present invention includes a step (1) of obtaining a first perovskite-type single crystal by firing a raw material containing an acceptor in an air atmosphere.

[0019] (Acceptor) The acceptor used in the method for producing a perovskite single crystal of the present invention may be selected from elements that have a lower valence and are substituted for some elements in the perovskite single crystal. The coercive field is improved by sintering raw materials containing acceptors in an air atmosphere to obtain a first perovskite single crystal. When an acceptor substitutes for a site in a perovskite single crystal with a lower valence than the original element, the charge balance of the crystal lattice is disrupted. To compensate for this, oxygen vacancies are generated at the oxygen sites, and the acceptor and oxygen vacancy form a dipole, generating an internal electric field. This internal electric field prevents polarization reversal due to an external electric field, improving the coercive field. When the raw material containing the acceptor is fired in an air atmosphere, it becomes difficult for the acceptor to enter vacancies as a substance other than the first single crystal, and more acceptors can be substituted into some sites of the perovskite structure.

[0020] For example, A 2+ B 4+ In perovskite oxides composed of O3, the acceptors substituting the A site can be one or more selected from Li, K, Na, etc. The acceptors substituting the B site can be one or more selected from Mg, Mn, Zn, Fe, Co, Al, Ni, Cr, Y, Sc, In, Bi, Yb, etc. Also, A 1+ B 5+ In the perovskite oxide of O3, the acceptor to substitute for the B site may be one or more selected from, for example, Mg, Mn, Zn, Fe, Co, Ni, Cr, Y, Sc, In, Yb, Ti, Zr, Sn, Hf, etc. Also, A 3+ B 3+ In the O3 perovskite oxide, the acceptor for substituting the A site can be one or more selected from Li, Na, K, Pb, Ba, Ca, etc. The acceptor for substituting the B site can be one or more selected from Mg, Mn, Fe, Co, Zn, etc. Here, the raw material used as the acceptor may be a metal, oxide, sulfide, or nitride as long as it contains the above-mentioned elements, and may be in a solid or liquid state.

[0021] The acceptor used in the method for producing a single crystal of the present invention is preferably Mn. Mn has a wide range of valence from 2 to 7, so A 2+ B 4+ O3, A 1+ B 5+ O3, A 3+ B 3+ O3 is preferable because it can act as an acceptor in either case. When Mn exists as an acceptor in a perovskite single crystal, oxygen vacancies are formed in the single crystal, and the Mn and oxygen vacancies form a dipole, generating an internal electric field. This internal electric field prevents polarization reversal due to an external electric field, improving the coercive field. Furthermore, when a donor element is generated by impurities or the like and conduction electrons are present, Mn is preferable because it traps the conduction electrons due to its low valence, thereby improving the insulation resistance.

[0022] The valence of a small amount of Mn added to a non-magnetic (diamagnetic) material can be evaluated by measuring the temperature dependence of magnetic susceptibility. Magnetic susceptibility can be measured using a superconducting quantum interference device (SQUID), a vibrating sample magnetometer (VSM), or a magnetic balance. The magnetic susceptibility χ obtained by measurement generally follows the Curie-Weiss law, expressed as Equation 1 below. χ=C / (T-θ) (C: Curie constant, θ: paramagnetic Curie temperature) (Formula 1)

[0023] Generally, when a small amount of Mn is added to a non-magnetic material, the spin S=5 / 2 is observed for a 2+ valence, S=2 for a 3+ valence, and S=3 / 2 for a 4+ valence. Therefore, the Curie constant C converted per unit Mn amount corresponds to the spin S value for each Mn valence. Therefore, the average valence of Mn in a sample can be evaluated by deriving the Curie constant C from the temperature dependence of the magnetic susceptibility χ.

[0024] (Fired in a reducing atmosphere and then in air) The method for producing a perovskite single crystal of the present invention is characterized by sequentially carrying out step (2), which includes a step of firing the first single crystal obtained by the above method in a reducing atmosphere, and step (3), which includes a step of firing the single crystal obtained in step (2) in an air atmosphere. By this method, a perovskite single crystal having a higher coercive field value than the first single crystal is obtained.

[0025] It is believed that in a perovskite-type first single crystal obtained by firing a raw material containing an acceptor in an air atmosphere, the acceptor is substituted with the same valence as the original element, or remains in a state other than the perovskite-type state in vacancies, etc. When such a first single crystal is fired in a reducing atmosphere, more oxygen vacancies than those present in the first single crystal are generated, and the remaining acceptors are incorporated into sites within the single crystal. As a result, more dipoles between acceptors and oxygen vacancies are formed, generating a larger internal electric field, which prevents the polarization from being reversed by the external electric field, resulting in a larger coercive field.

[0026] Furthermore, single crystals that have undergone a process of firing in a reducing atmosphere have a relative dielectric constant of ε 33 The maximum value of the piezoelectric constant d 33 The fluctuation range (%) becomes smaller. Generally, when the temperature of a piezoelectric material changes toward the phase transition temperature, the polarization is reconstructed or eliminated, resulting in a change in polarization due to an external electric field, i.e., an increase in the dielectric constant. This change is more pronounced in the case of a single crystal. However, when the internal electric field increases due to acceptors, the polarization becomes less likely to change due to an external electric field, resulting in a decrease in the dielectric constant. Also, the piezoelectric constant d 33 is a function of the relative permittivity as shown in equation (2) below, and for the same reason, the range of fluctuation due to temperature changes becomes smaller.

number

[0027] (Firing in a reducing atmosphere) Next, the step (2) including the step of firing the first single crystal in a reducing atmosphere will be specifically described with reference to FIGS. Figure 1 is a schematic diagram showing the configuration of a reducing atmosphere firing furnace 2 for firing a first single crystal 1 in a reducing atmosphere. In Figure 1, the first single crystal 1 is placed in a high-temperature electric furnace 3, and the atmosphere inside the high-temperature electric furnace 3 is configured to be replaced with a gas such as an inert gas discharged from a gas cylinder 4. An oxygen partial pressure controller 5 is also installed to control the oxygen partial pressure inside the high-temperature electric furnace. For example, an SiOC-200CB (manufactured by ST Labs, Inc.) can be used as the oxygen partial pressure controller.

[0028] FIG. 2 is an example of a configuration diagram when the first single crystal 1 is placed in a reducing atmosphere firing furnace 2. The first single crystal 1 is placed on a setter 6, and in this state, it is placed in the high-temperature electric furnace 3 shown in FIG.

[0029] The setter 6 is preferably made of a material that is less reactive with the first single crystal 1, such as alumina, zirconia, alumina with a zirconia surface coating, stabilized zirconia, silicon carbide, silicon nitride, etc. If it is difficult to determine whether a material is less reactive, try each material and select the one that leaves the least traces when fired.

[0030] (reducing atmosphere) The reducing atmosphere may be a space filled with an oxygen-free gas or a vacuum, and the gas may be one or more selected from, for example, hydrogen, helium, carbon monoxide, hydrocarbons, argon, nitrogen, ammonia, etc., but is preferably a gas containing argon. Among inert gases, argon is preferred because it is less likely to react with the first single crystal, allowing more oxygen vacancies to be generated, further improving the coercive field. The argon content of 90 mol % or more is preferred because the effect of generating oxygen vacancies is more pronounced. Furthermore, the oxygen partial pressure P(O2) in the reducing atmosphere is 1×10 ―10 It is preferable that the oxygen partial pressure is 1×10 Pa or less. ―10 If the pressure is 100 Pa or less, more oxygen vacancies can be generated, which is preferable because the coercive field is further improved. The firing temperature in the step of firing in a reducing atmosphere in step (2) is preferably equal to or lower than the firing temperature in step (1) for producing the first single crystal, and is preferably equal to or higher than 1280° C. When firing is performed at a temperature lower than the temperature for producing the first single crystal, heterophases that are crystals different from perovskite are less likely to occur, and the single crystal structure is more likely to be maintained, resulting in a single crystal having a high electromechanical coupling coefficient.

[0031] (Firing in air) Next, step (3) will be described, which comprises a step of firing in an air atmosphere the single crystal obtained through step (2) which comprises a step of firing the first single crystal in a reducing atmosphere. FIG. 3 is a schematic diagram for explaining the first embodiment of the present invention.

[0032] Step (3) according to the present invention comprises a step of firing the first single crystal 1 in a reducing atmosphere and then firing it in an air atmosphere. In step (3), as shown in Fig. 3, the first single crystal 1 fired in a reducing atmosphere is placed on a setter 6, placed in a sagger 7, and fired in an electric furnace. The sagger 7 may be covered with a lid (not shown) during firing to prevent the intrusion of impurities from the surroundings. The step of firing in an air atmosphere may be carried out using a normal electric furnace, for example, a super electric furnace (manufactured by Yamada Electric Co., Ltd., model SSFT-1520).

[0033] The single crystal of the present invention obtained by firing the first single crystal 1 in a reducing atmosphere and then firing it in an air atmosphere has a high electromechanical coupling coefficient when used as a piezoelectric element because the heterophase that occurs when firing in a reducing atmosphere is removed.

[0034] The firing temperature in the air atmosphere in step (3) is preferably equal to or lower than the firing temperature in the reducing atmosphere in step (2), and is preferably equal to or lower than 1000° C. When the firing temperature in the air atmosphere is equal to or lower than the firing temperature in the reducing atmosphere, the oxygen vacancies introduced during firing in the reducing atmosphere can be maintained better, and a higher coercive field can be obtained.

[0035] (First method for producing single crystals) Next, an example of a specific method for producing the first single crystal 1 will be described. The step of obtaining the first single crystal 1 of the present invention is preferably a solid phase growth method. The solid phase growth method for producing the first single crystal 1 is preferable because it does not require the process of melting and cooling the material as in the liquid phase method, and therefore it is possible to produce a first single crystal 1 having approximately the same composition as the raw material containing the acceptor, even if the addition of an acceptor results in an incongruent melt composition (non-congruent composition).

[0036] An embodiment in which the step of obtaining the first single crystal is performed by solid phase growth will be described below. Fig. 4 is a schematic diagram showing one embodiment of the integrated product of the present invention, which is made up of a seed single crystal 11 and a matrix 12. In Fig. 4, the seed single crystal 11 is provided on top of the matrix 12, and the surface of the matrix 12 and the surface of the seed single crystal 11 are arranged in contact with each other to form an integrated product. The first method for producing a single crystal according to the present invention is a method for producing a single crystal by firing a monolithic matrix 12 as shown in FIG.

[0037] (Matrix explanation) 4 may be a molded body or a sintered body. The raw material used for the matrix 12 is a solid powder of an oxide, carbonate, nitrate, oxalate, or the like of the constituent elements of the single crystal of the present invention, including the acceptor, or a mixed powder of these.

[0038] Preferred elements constituting the raw material of the matrix 12 include, for example, Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, In, Sn, Sb, Ba, Hf, Ta, Pb, Bi, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb. However, it is more preferable that the content of lead (Pb) contained in the raw materials is less than 1000 ppm, as this reduces the burden on the environment.

[0039] For example, when using elements Ba, Ti, and Zr and Mn as an acceptor, usable Ba raw materials include barium oxide, barium carbonate, barium oxalate, barium acetate, barium nitrate, barium titanate, barium zirconate, etc. It is preferable to use commercially available high-purity Ba compounds (e.g., 99.99% or higher purity).

[0040] Usable Ti raw materials include titanium oxide, barium titanate, barium titanate zirconate, etc. When these Ti compounds contain alkaline earth metals such as barium, it is preferable to use commercially available high-purity compounds (e.g., purity of 99.99% or higher). It may contain Nb to the extent that it is contained as an unavoidable component in commercially available raw materials for Ti, and Hf to the extent that it is contained as an unavoidable component in commercially available raw materials for Zr.

[0041] Usable Zr raw materials include zirconium oxide, barium zirconate, barium titanate zirconate, etc. When these Zr compounds contain alkaline earth metals such as barium, it is preferable to use commercially available high-purity compounds (e.g., purity of 99.99% or higher).

[0042] Usable Mn raw materials include manganese carbonate, manganese oxide, manganese dioxide, manganese acetate, and trimanganese tetroxide.

[0043] Furthermore, it is preferable that the raw material of the matrix 12 contains Bi. When the Bi content is 0.20 parts by mass or less in terms of metal with respect to 100 parts by mass of the perovskite metal oxide, which is the main component of the matrix 12, trivalent Bi can occupy the A site. This makes it easier for Mn in the B site to take on a valence lower than 4+ in order to achieve charge balance, and it becomes easier for Mn to behave as an acceptor.

[0044] When Bi is used as the raw material for the matrix 12, usable Bi raw materials include bismuth oxide and bismuth chloride.

[0045] A compound that promotes single crystallization by solid phase growth may be added to the raw material of matrix 12. Examples of the promoting element include lithium (Li), silicon (Si), and aluminum (Al). Preferably, the content of Li is 0.05 to 0.20 parts by mass in terms of metal per 100 parts by mass of the perovskite metal oxide, which is the main component of matrix 12.

[0046] When Li is used as the raw material of the matrix 12, usable Li raw materials include lithium carbonate, lithium tetraborate, and lithium acetate.

[0047] Furthermore, there are no particular limitations on the raw materials for adjusting the amount of Ba present at the A site of the single crystal according to the present invention and the molar ratio a of Ti and Zr at the B site. The same effect can be obtained with any of Ba compounds, Ti compounds, and Zr compounds.

[0048] (Granulation of raw materials for preparing the matrix) The raw material of the matrix 12 used in the method for producing a single crystal of the present invention may be granulated, and the granulation method is not particularly limited. Examples of binders that can be used in granulation include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), and acrylic resins.

[0049] (Molded body of raw material for producing matrix) The molded body of the matrix 12 used in the method for producing a single crystal of the present invention is a molded body obtained by solidifying the above-mentioned raw materials into a desired shape, and the method for producing the molded body is not particularly limited. The molded body is a solid body made from raw material powder, granulated powder (binder), or slurry.

[0050] The molded body can be produced by uniaxial pressing, cold isostatic pressing, warm isostatic pressing, slip casting, extrusion, etc. Alternatively, the raw material in a slurry state can be formed into a sheet using a doctor blade method, dried, and the sheets can be stacked and molded into the desired shape.

[0051] (sintering) When the matrix 12 is used as a sintered body, the above-mentioned molded body may be sintered by any means, and examples of the sintering method include sintering in an electric furnace, sintering in a gas furnace, hot pressing, resistance heating, microwave sintering, millimeter wave sintering, HIP (hot isostatic pressing), and flash sintering.

[0052] (seed single crystal) The seed single crystal 11 used to produce the first single crystal may be either bulk or thin film. The seed single crystal 11 may be prepared by selecting from commercially available oxide single crystals, semiconductor single crystals, fluoride / alkali halide single crystals, metal single crystals, alloy single crystals, etc., but a perovskite-type single crystal is preferred because stress due to mismatch in lattice constant with the matrix 12 and differences in thermal expansion are less likely to occur.

[0053] The perovskite single crystal used as the seed single crystal 11 may be BaTiO3, BaZrO3, SrTiO3, CaTiO3, Pb(Mg 1 / 3 Nb 2 / 3 )O3, KTaO3, KNbO3, SrRuO3, LiNbO3, LaNiO3, AgNbO3, CdTiO3, and solid solutions thereof. Furthermore, the first single crystal obtained by the above-mentioned method may be used as the seed single crystal 11 used to produce the first single crystal.

[0054] (polishing) Next, the matrix 12 and the seed single crystal 11 obtained by sintering as described above are polished, and the polished surfaces of the matrix 12 and the seed single crystal 11 are arranged in contact with each other to form an integrated body, thereby increasing the contact area. Polishing methods include mechanical polishing, chemical polishing, and CMP polishing, and these may be combined.

[0055] (sacks, setters, beads, weights) Figures 5, 6, and 7 are schematic diagrams showing examples of the configuration for producing a first single crystal. In Figure 5, a weight 14 is placed on an integral body of a matrix 12 and a seed single crystal 11, and the integral body is placed on a setter 16 via beads 15. In Figure 6, these are placed in a sagger 17, and in Figure 7, the sagger 17 of Figure 6 is covered with a lid 18. The sagger 17 with the lid 18 is placed in an electric furnace and fired.

[0056] It is preferable that the matrix 12 and the seed single crystal 11 are arranged one above the other so as to be in contact with each other. Furthermore, it is preferable to place a weight 14 on the matrix 12 and the seed single crystal 11, since this facilitates contact between the matrix 12 and the seed single crystal 11. Even if a force acts in a direction that separates the matrix 12 and the seed single crystal 11 due to deformation during heat treatment or the like, the weight 14 acts in a direction that suppresses this force, making it easier for them to come into contact with each other.

[0057] The matrix 12 and the seed single crystal 11 may be placed on a setter 16 that is less reactive with the matrix 12 and the seed single crystal 11 and then heat-treated. The setter 16 may be made of, for example, alumina, zirconia, alumina with a zirconia surface coating, stabilized zirconia, silicon carbide, or silicon nitride. Beads 15 such as stabilized zirconia, powder obtained by sintering and pulverizing the matrix 12 at high temperature, or a platinum sheet may be placed on the setter 16, and the matrix 12 and the seed single crystal 11 may then be placed on top of them. If it is difficult to determine whether a material is less reactive, try each material and select the one that leaves the least traces when fired.

[0058] (liquid phase of matrix) The matrix 12 used to prepare the first single crystal 1 has a liquid phase start temperature and a liquid phase finish temperature. The liquid phase here refers to a state in which at least a portion of the matrix 12 is in a liquid phase, and also refers to a state in which a solid phase and a liquid phase coexist. The state and temperature can be confirmed, for example, by placing a sample on a microscope heating stage (manufactured by LINKAM) and heating it, and observing the surface of the matrix 12 under a microscope. Specifically, the liquid phase start temperature is the temperature at which the matrix 12 becomes liquid when at least some of the grain boundaries of the matrix 12 become invisible during heating, and the liquid phase finish temperature is the temperature at which at least some of the grain boundaries of the matrix 12 appear upon further heating.

[0059] As another method, since the liquid phase becomes amorphous when rapidly cooled, the matrix 12 is heated to near the liquid phase temperature, and the heated matrix 12 is placed in tap water at room temperature and rapidly cooled. After that, the structure is analyzed by X-ray diffraction, and the temperature at which the matrix becomes liquid can be confirmed by checking whether or not there is an amorphous region.

[0060] However, the liquidus start temperature in the present invention varies due to factors such as contamination with impurities in the preparation process, uneven pressure during molding, and voids. Therefore, the liquidus start temperature is defined as a temperature within ±50°C of the lowest temperature at which the liquidus can be confirmed by the above means. Also, the liquidus end temperature is defined as a temperature within ±50°C of the highest temperature at which the liquidus can be confirmed by the above means.

[0061] When the interface between seed single crystal 11 and matrix 12 becomes liquid, the interface of the single crystal region of seed single crystal 11 gradually expands toward matrix 12. At this time, it is thought that the difference in surface energy causes the crystal grains of matrix 12 to be incorporated into the single crystal. Therefore, if the crystal grains of matrix 12 are too large, the difference in surface energy becomes small, making it difficult for matrix 12 to be incorporated into the single crystal.

[0062] Therefore, when preparing the matrix 12 as a sintered body, it is preferable to sinter it at a temperature that prevents the crystal grains from becoming too large. As a means for preventing the crystal grains from becoming too large, a method of sintering in a reducing atmosphere such as nitrogen or argon may be used.

[0063] (Firing method) In the first heating step, the second heating step, and the firing step described below, the method for firing the integral body of matrix 12 and seed single crystal 11 is not particularly limited except that firing is performed in an air atmosphere. However, sintering using an electric furnace is preferred in that a large number of bodies can be fired at once and production costs can be reduced.

[0064] [First heating step] The method for producing the first single crystal 1 includes a first heating step in which the temperature of the monolith is raised from room temperature to the liquid phase initiation temperature of the matrix.

[0065] In the first heating step, in which the temperature is raised to the liquidus start temperature, crystal grains grow uniformly within the matrix. As mentioned above, if the crystal grains of matrix 1 become too large, it becomes difficult for matrix 12 to be incorporated into the first single crystal. Therefore, it is preferable to set the first heating step to a short time so that the crystal grains do not become too large.

[0066] [Second heating step] The method for producing the first single crystal 1 also includes a second heating step of heating the integral body from the liquid phase start temperature to the liquid phase finish temperature of the matrix 12 .

[0067] In the second heating step, the interface between seed single crystal 11 and matrix 12 becomes liquid, and the single crystal interface spreads toward matrix 12. However, if the temperature varies depending on the location due to differences in the orientation of the crystal grains of matrix 12 in contact with seed single crystal 11, the interfaces of crystal grains with different orientations in matrix 12 also spread at the same time, and it may not be possible to obtain a single crystal that is a single crystal grain.

[0068] Therefore, by reducing the temperature increase rate from the liquid phase start temperature to the liquid phase end temperature in the second heating step compared to the temperature increase rate from room temperature to the liquid phase start temperature in the first heating step, it is possible to expand a single crystal region consisting of a single crystal grain from the seed single crystal 11. After the temperature is increased, the single crystal region spreading from the seed single crystal 11 can be further enlarged by maintaining the temperature at the liquid phase end temperature.

[0069] [Step of obtaining a first single crystal] The method for producing the first single crystal 1 includes a step of obtaining the first single crystal 1 from the matrix 12 after it has been fired. After the second heating step, the single crystal regions within the matrix can be determined by checking for grain boundaries under a microscope. Regions without grain boundaries are single crystal regions consisting of a single crystal grain. Structural analysis using X-ray diffraction or electron diffraction can also be used to confirm this.

[0070] The polycrystalline portion and the seed single crystal 11 portion other than the single crystal region can be removed using a wire saw, a dicing saw, water jet cutting, electrical discharge machining, laser machining, polishing, or the like to obtain only the single crystal region, and thus a first single crystal can be obtained.

[0071] The first single crystal is a single crystal containing Mn and a perovskite-type oxide containing Ba, Ti, and Zr, where x, the molar ratio of Zr to the sum of Ti and Zr, is 0.02≦x≦0.13, and the Mn content is preferably 0.04 parts by mass or more and 0.36 parts by mass or less in terms of metal per 100 parts by mass of the oxide. When Zr and Mn are contained within the above ranges, abnormal grain growth is less likely to occur in areas other than the interface between the seed single crystal 11 and the matrix 12. If abnormal grain growth occurs in areas other than the interface between the seed single crystal 11 and the matrix 12, that area will hinder the growth of the single crystal spreading from the interface between the seed single crystal 11 and the matrix 12. Furthermore, it is more preferable that the first single crystal contains an oxide containing Ba, Ti, and Zr, as well as Mn, Bi, and Li, wherein x, which is the molar ratio of Zr to the sum of the Ti and Zr, is 0.02≦x≦0.13, the Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less, calculated as a metal, per 100 parts by mass of the oxide, the Bi content is more than 0 parts by mass and 0.20 parts by mass or less, calculated as a metal, per 100 parts by mass of the oxide, and the Li content is 0.05 parts by mass or more and 0.20 parts by mass or less, calculated as a metal, per 100 parts by mass of the oxide.

[0072] By sequentially carrying out step (2), which includes a step of firing the first single crystal obtained by the solid-phase growth method in a reducing atmosphere, and step (3), which includes a step of firing the single crystal obtained in step (2) in an air atmosphere, a perovskite-type single crystal of the present invention having a higher coercive field value than the first single crystal can be obtained.

[0073] <Second embodiment> The second embodiment relates to a perovskite-type single crystal of the present invention. The perovskite single crystal of the present invention is a single crystal containing Mn and an oxide having a perovskite structure containing Ba, Ti, and Zr, wherein x, which is a molar ratio of Zr to the sum of Ti and Zr, is 0.02≦x≦0.13, the content of Mn is 0.04 parts by mass or more and 0.36 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, the single crystal may contain Bi, and the content of Bi is 0 parts by mass or more and 0.20 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, and the electromechanical coupling coefficient k 33 is 80% or more, and the coercive field is 2.5 kV / cm or more.

[0074] Here, the content of Mn "converted to metal" refers to the following: The content of each metal, Ba, Ti, Zr, and Mn, is measured from the single crystal by X-ray fluorescence analysis (XRF), ICP emission spectroscopy, atomic absorption spectroscopy, etc. From the content, the elements constituting the oxide represented by the following general formula (3) are converted to oxides, and the total mass is taken as 100, and the value is calculated as the ratio of the mass of Mn to the total mass. Ba a (Ti 1-x , Zr x )O3(3)

[0075] The single crystal of the present invention preferably contains less than 1000 ppm of Pb. The single crystal of the present invention does not use lead, thereby reducing the burden on the environment.

[0076] The oxide represented by the general formula (3) means that the element located at the A site is Ba, and the elements located at the B site are Ti and Zr. However, some Ba may be located at the B site. Similarly, some Ti and Zr may be located at the A site. In the general formula (3), the molar ratio of the B-site element to the O element is 1:3, but the ratio of the amounts of the elements may be different due to oxygen vacancies generated by substituting Mn into the B-site.

[0077] The single crystal of the present invention preferably contains the perovskite-type oxide represented by the general formula (3) as the main component in an amount of 90 mol % or more, more preferably 95 mol % or more.

[0078] In the general formula (3), x, which represents the molar ratio of Zr in the B site, is in the range of 0.02≦x≦0.13. If x is greater than 0.13, the Curie temperature becomes too low, resulting in insufficient high-temperature durability. If x is less than 0.02, the piezoelectric constant at room temperature becomes small.

[0079] The Curie temperature (Tc) is the temperature at which a material loses its ferroelectricity. Normally, piezoelectric materials lose their piezoelectric performance above Tc. There are two ways to measure Tc: directly measuring the temperature at which ferroelectricity disappears while changing the measurement temperature, or measuring the relative dielectric constant while changing the measurement temperature using a small AC electric field, and determining the temperature at which the relative dielectric constant reaches its maximum.

[0080] The means for measuring the composition of the single crystal of the present invention is not particularly limited. Examples of the means include X-ray fluorescence analysis, ICP emission spectroscopy, and atomic absorption spectroscopy. Any of the means can calculate the mass ratio and composition ratio of each element contained in the single crystal.

[0081] The single crystal of the present invention has improved insulation resistance when it contains Mn within the above range. When the Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less, when a piezoelectric element comprising the single crystal and a pair of electrodes is used as a device, the insulation resistance is high, and therefore no excess current flows even when a voltage is applied to drive the device, resulting in low power consumption.

[0082] On the other hand, if the Mn content is greater than 0.36 parts by mass, the amount of heterophases other than the perovskite single crystal increases, resulting in a decrease in the insulating properties of the single crystal. For example, the dielectric loss tangent at a frequency of 1 kHz may exceed 0.01, and the resistivity may fall below 1 GΩcm. The dielectric loss tangent can be measured using an impedance analyzer. If the dielectric loss tangent is 0.01 or less, stable operation can be achieved even when high voltages are applied when the single crystal is used as a piezoelectric element.

[0083] If the single crystal has a resistivity of 1 GΩcm, it can be polarized and driven as a piezoelectric element. A more preferable resistivity is 50 GΩcm or higher. Furthermore, the electromechanical coupling coefficient k of the single crystal at 25°C 33 If the ratio is 80% or more, when a piezoelectric element comprising the single crystal and a pair of electrodes is used as a vibration device, the conversion efficiency from electrical energy to mechanical energy is high and power consumption is reduced. Furthermore, if the coercive electric field of the single crystal is 2.5 kV / cm or more, when a piezoelectric element consisting of the single crystal and a pair of electrodes is used as a vibration device, it can be driven without losing piezoelectric performance even in products that are driven by large voltages, such as ultrasonic motors and piezoelectric acoustic components. The preferred coercive field for single crystals used in vibrating devices is 4 kV / cm or higher. This range allows a wider range of products to be driven without losing piezoelectric performance.

[0084] The single crystal of the present invention has a piezoelectric constant d 33 It is preferable that the fluctuation range (%) is 65% or less. 100×Δd 33@0℃~70℃ / d 33@0℃(4) The single crystal of the present invention has a relative dielectric constant ε 33 It is preferable that the maximum value is 6500 or less. The single crystal of the present invention has a relative dielectric constant ε 33 It is preferable that the maximum value is 4200 or less.

[0085] As mentioned above, when a piezoelectric material is made into a single crystal, the relative dielectric constant ε 33 and the piezoelectric constant d 33 The fluctuations in the dielectric constant become extremely large. Therefore, when piezoelectric single crystals are used in products such as home appliances, for example, in devices such as ultrasonic motors in cameras, the relative permittivity of the piezoelectric material increases and the piezoelectric constant fluctuates (for example, by more than 65%) within the product's operating temperature range (for example, from 0°C to 70°C). When the relative permittivity increases, the capacitance component of the drive circuit increases, and the current flowing through the circuit increases. As a result, power consumption during operation increases. Furthermore, fluctuations in the piezoelectric constant change the device's output characteristics (mainly vibration amplitude), resulting in poor controllability. Therefore, when single crystals are used in products such as home appliances, it is necessary that the variation in the piezoelectric constant be small within the operating temperature range of the product. If the variation in the piezoelectric constant due to temperature is 65% or less, stable product performance can be obtained within the operating temperature range. In addition, the relative dielectric constant ε in the range of 0°C to 70°C 33 If the maximum value is 6500 or less, power consumption will be small when used within the operating temperature range. In addition, the relative dielectric constant ε in the range of 0°C to 60°C 33 If the maximum value is 4200 or less, the temperature range from 0°C to 60°C is an even more frequently used temperature range, so if the maximum value is 4200 or less within the operating temperature range, power consumption will be even smaller.

[0086] <Application example> An application example of the present invention will be described below. (piezoelectric element) The piezoelectric element of the present invention has a plurality of electrodes and the above-described single crystal. 8 is a schematic diagram showing one embodiment of the configuration of a piezoelectric element of the present invention. The piezoelectric element of the present invention is a piezoelectric element having at least a first electrode 21, a single crystal portion 22, and a second electrode 23, and is characterized in that the single crystal portion 22 is the single crystal of the present invention.

[0087] The single crystal according to the present invention can be formed into a piezoelectric element having at least a first electrode 21 and a second electrode 23, allowing the electromechanical coupling coefficient, coercive field, piezoelectric constant, and relative dielectric constant of the single crystal to be evaluated. The first electrode 21 and the second electrode 23 are made of conductive layers having a thickness of approximately 5 nm to 10 μm. The material for the electrodes is not particularly limited, and any material commonly used for piezoelectric elements may be used. Examples of the material include metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu, alloys, and compounds thereof.

[0088] The first electrode 21 and the second electrode 23 may be made of one of these materials or may be made by laminating two or more of these materials. Also, the first electrode 21 and the second electrode 23 may be made of different materials.

[0089] The manufacturing method of the first electrode 21 and the second electrode 23 is not limited, and they may be formed by baking a metal paste, or by sputtering, vapor deposition, etc. Furthermore, both the first electrode 21 and the second electrode 23 may be patterned into a desired shape before use.

[0090] (Polarization treatment) It is more preferable that the polarization axis of the piezoelectric element is aligned in a certain direction, since the polarization axis is aligned in a certain direction, the electromechanical coupling coefficient of the piezoelectric element is increased.

[0091] The polarization method for the piezoelectric element is not particularly limited. The polarization process may be performed in air or in silicone oil. The temperature during polarization is preferably a temperature at which the single crystal undergoes a phase transition. For example, a temperature of 60°C to 150°C is preferable, but the optimal conditions will vary somewhat depending on the composition of the single crystal that constitutes the element. The electric field applied for polarization is preferably 8 kV / cm to 20 kV / cm, and it is preferable to terminate the application of the electric field after lowering the ambient temperature to a temperature at which the single crystal has the same crystal structure as at room temperature, as this will result in a good electromechanical coupling coefficient.

[0092] The piezoelectric element according to the present invention also includes a laminated piezoelectric element in which a number of single crystals according to the present invention are stacked, or a number of piezoelectric elements are stacked to form a rod-like shape and the displacement in the thickness direction is utilized.

[0093] (ultrasonic motor) The ultrasonic motor of the present invention includes a vibrating body with the above-described piezoelectric element and a moving body in contact with the vibrating body. This configuration provides an ultrasonic motor with drive efficiency equal to or greater than that of a piezoelectric element containing lead. Figure 9 is a schematic diagram showing one embodiment of the configuration of an ultrasonic motor of the present invention. Figure 9 shows an ultrasonic motor in which the piezoelectric element of the present invention is a single plate. The ultrasonic motor includes a vibrating body 201, a rotor 202 that contacts the sliding surface of the vibrating body 201 with the pressure of a compression spring (not shown), and an output shaft 203 that is integral with the rotor 202. The vibrating body 201 is composed of a metal elastic ring 2011, a piezoelectric element 2012 of the present invention, and an organic adhesive 2013 (e.g., epoxy-based, cyanoacrylate-based, etc.) that bonds the piezoelectric element 2012 to the elastic ring 2011. The piezoelectric element 2012 of the present invention is composed of a single crystal sandwiched between a first electrode 21 and a second electrode 33 (not shown). When a two-phase alternating voltage with a phase difference of an odd multiple of π / 2 is applied to the piezoelectric element of the present invention, a flexural traveling wave is generated in the vibrator 201, causing each point on the sliding surface of the vibrator 201 to undergo elliptical motion. When a rotor 202 is pressed against the sliding surface of the vibrator 201, the rotor 202 receives a frictional force from the vibrator 201 and rotates in the opposite direction to the flexural traveling wave. A driven body (not shown) is connected to the output shaft 203 and is driven by the rotational force of the rotor 202. When a voltage is applied to the single crystal, the single crystal expands and contracts due to the piezoelectric transverse effect. The efficiency of this conversion from electrical energy to mechanical energy depends on the magnitude of the electromechanical coupling coefficient. When an elastic material such as metal is bonded to the piezoelectric element with an adhesive, the elastic material is bent by the expansion and contraction of the single crystal via the adhesive. The ultrasonic motor of the type described here utilizes this principle.

[0094] (optical equipment) The optical device of the present invention includes the ultrasonic motor described above in its driving section, thereby providing an optical device with operating speed and efficiency equal to or greater than those using piezoelectric elements containing lead.

[0095] Figures 10A and 10B are cross-sectional views of the main components of an interchangeable lens barrel for a single-lens reflex camera, which is a preferred embodiment of the optical apparatus of the present invention. Also, Figure 11 is an exploded perspective view of an interchangeable lens barrel for a single-lens reflex camera, which is a preferred embodiment of the optical apparatus of the present invention. A fixed barrel 712, a linear guide barrel 713, and a front group barrel 714 are fixed to a detachable mount 711 for the camera. These are fixed members of the interchangeable lens barrel.

[0096] A linear guide groove 713a in the optical axis direction for the focus lens 702 is formed in the linear guide barrel 713. Cam rollers 717a and 717b protruding radially outward are fixed to a rear group barrel 716 that holds the focus lens 702 with shaft screws 718, and the cam roller 717a fits into the linear guide groove 713a.

[0097] A cam ring 715 is rotatably fitted onto the inner periphery of the linear guide barrel 713. Relative movement between the linear guide barrel 713 and the cam ring 715 in the optical axis direction is restricted by a roller 719 fixed to the cam ring 715 fitting into a circumferential groove 713b of the linear guide barrel 713. A cam groove 715a for the focus lens 702 is formed in this cam ring 715, and the above-mentioned cam roller 717b is fitted into the cam groove 715a at the same time.

[0098] A rotation transmission ring 720 is arranged on the outer periphery of the fixed barrel 712, and is held in a fixed position and rotatable relative to the fixed barrel 712 by a ball race 727. In the rotation transmission ring 720, rollers 722 are rotatably held on shafts 720f extending radially from the rotation transmission ring 720, and large diameter portions 722a of the rollers 722 are in contact with the mount side end surface 724b of the manual focus ring 724. In addition, small diameter portions 722b of the rollers 722 are in contact with the joining member 729. Six rollers 722 are arranged at equal intervals on the outer periphery of the rotation transmission ring 720, and each roller is configured as described above.

[0099] A low-friction sheet (washer member) 733 is disposed on the inner diameter portion of the manual focus ring 724, and this low-friction sheet is sandwiched between a mount-side end face 712a of the fixed barrel 712 and a front end face 724a of the manual focus ring 724. The outer diameter surface of the low-friction sheet 733 is ring-shaped and fits radially into an inner diameter 724c of the manual focus ring 724, which in turn fits radially into an outer diameter portion 712b of the fixed barrel 712. The low-friction sheet 733 serves to reduce friction in the rotating ring mechanism in which the manual focus ring 724 rotates relative to the fixed barrel 712 around the optical axis.

[0100] The large-diameter portion 722a of the roller 722 and the mount-side end surface 724b of the manual focus ring are in contact with each other under pressure due to the force of the wave washer 726 pressing the ultrasonic motor 725 toward the front of the lens. Similarly, the force of the wave washer 726 pressing the ultrasonic motor 725 toward the front of the lens also causes contact between the small-diameter portion 722b of the roller 722 and the joining member 729 under pressure. Movement of the wave washer 726 toward the mount direction is restricted by washer 732, which is bayonet-connected to the fixed barrel 712. The spring force (biasing force) generated by the wave washer 726 is transmitted to the ultrasonic motor 725 and further to the roller 722, and also acts as a pressing force between the manual focus ring 724 and the mount-side end surface 712a of the fixed barrel 712. That is, the manual focus ring 724 is assembled in a state where it is pressed against the mount-side end surface 712 a of the fixed barrel 712 via the low-friction sheet 733 .

[0101] Therefore, when the ultrasonic motor 725 is driven to rotate relative to the fixed barrel 712 by a control unit (not shown), the joining member 729 is in frictional contact with the small diameter portion 722b of the roller 722, causing the roller 722 to rotate around the center of the shaft 720f. When the roller 722 rotates around the shaft 720f, the rotation transmission ring 720 rotates around the optical axis (autofocus operation).

[0102] Furthermore, when a rotational force about the optical axis is applied to manual focus ring 724 from a manual operation input unit (not shown), roller 722 rotates about axis 720f due to frictional force because mount-side end surface 724b of manual focus ring 724 is in pressure contact with large-diameter portion 722a of roller 722. When large-diameter portion 722a of roller 722 rotates about axis 720f, rotation transmission ring 720 rotates about the optical axis. At this time, ultrasonic motor 725 does not rotate due to the frictional holding force between rotor 725c and stator 725b (manual focus operation).

[0103] Two focus keys 728 are attached to the rotation transmission ring 720 at positions facing each other, and the focus keys 728 fit into notches 715b provided at the tip of the cam ring 715. Therefore, when autofocusing or manual focusing is performed and the rotation transmission ring 720 is rotated about the optical axis, the rotational force is transmitted to the cam ring 715 via the focus keys 728. When the cam ring is rotated about the optical axis, the rear group barrel 716, whose rotation is restricted by the cam rollers 717a and the rectilinear guide grooves 713a, moves forward and backward along the cam grooves 715a of the cam ring 715 by the cam rollers 717b. This drives the focus lens 702, and the focusing operation is performed.

[0104] Here, we have described an interchangeable lens barrel for a single-lens reflex camera as the optical device of the present invention, but the present invention can also be applied to optical devices that have an ultrasonic motor in the drive section, regardless of the type of camera, such as compact cameras, electronic still cameras, and camera-equipped personal digital assistants.

[0105] (Vibration device and dust removal device) The vibration device of the present invention has a vibrating body with the above-mentioned piezoelectric element disposed on a diaphragm, thereby providing a vibration device with vibration capacity equal to or greater than that of a vibration device using a piezoelectric element containing lead. Vibration devices are widely used in electronic devices and other applications to transport and remove particles, powders, and droplets.

[0106] As an example of the vibration device of the present invention, a dust removing device using the vibration device of the present invention will be described below.

[0107] The dust removal device according to the present invention has a vibration device in the vibration section, and thus can provide a dust removal device having dust removal efficiency equal to or greater than that of a dust removal device using a piezoelectric element containing lead.

[0108] 12A and 12B are schematic diagrams showing one embodiment of a dust removal device of the present invention. Dust removal device 310 is composed of a plate-shaped piezoelectric element 330 and a vibration plate 320. The material of vibration plate 320 is not limited, but when dust removal device 310 is used in an optical device, a light-transmitting material or a light-reflective material can be used for vibration plate 320.

[0109] Figures 13A to 13C are schematic diagrams showing the configuration of piezoelectric element 330 in Figures 12A and 12B. Figures 13A and 13C show the configuration of the front and back surfaces of piezoelectric element 330, and Figure 13B shows the configuration of the side surface. As shown in Figure 12A, piezoelectric element 330 is composed of single crystal 331, first electrode 332, and second electrode 333, and first electrode 332 and second electrode 333 are arranged opposite the plate surface of single crystal 331.

[0110] In Figure 13B, the surface on which the first electrode 332 protruding in front of the piezoelectric element 330 is placed is referred to as the first electrode surface 336, and in Figure 13A, the surface on which the second electrode 333 protruding in front of the piezoelectric element 330 is placed is referred to as the second electrode surface 337.

[0111] Here, the electrode surface in the present invention refers to the surface of the piezoelectric element on which the electrode is provided, and for example, the first electrode 332 may wrap around to the second electrode surface 337 as shown in FIGS. 13A and 13B.

[0112] 12A and 12B, piezoelectric element 330 and diaphragm 320 are fixed to the plate surface of diaphragm 320 at first electrode surface 336 of piezoelectric element 330. When piezoelectric element 330 is driven, stress is generated between piezoelectric element 330 and diaphragm 320, causing out-of-plane vibration in the diaphragm. Dust removal device 310 of the present invention is a device that removes foreign matter such as dust adhering to the surface of diaphragm 320 by the out-of-plane vibration of diaphragm 320. Out-of-plane vibration refers to elastic vibration that displaces the diaphragm in the optical axis direction, i.e., in the thickness direction of the diaphragm.

[0113] 14A and 14B are schematic diagrams illustrating the vibration principle of dust removal device 310 of the present invention. FIG. 14A illustrates a state in which in-phase alternating voltages are applied to a pair of left and right piezoelectric elements 330, causing out-of-plane vibrations in diaphragm 320. The polarization direction of the single crystals constituting the pair of left and right piezoelectric elements 330 is the same as the thickness direction of piezoelectric elements 330, and dust removal device 310 is driven in a seventh-order vibration mode. FIG. 14B illustrates a state in which out-of-phase alternating voltages, 180° out of phase, are applied to the pair of left and right piezoelectric elements 330, causing out-of-plane vibrations in diaphragm 320. Dust removal device 310 is driven in a sixth-order vibration mode. Dust removal device 310 of the present invention is a device that can effectively remove dust adhering to the surface of the diaphragm by selectively using at least two vibration modes.

[0114] (imaging device) The imaging device of the present invention includes at least the dust removal device and an imaging element unit, and the diaphragm of the dust removal device is provided on the light receiving surface side of the imaging element unit. This provides an imaging device with dust removal capabilities equal to or better than those achieved by using a piezoelectric element containing lead. Figures 15 and 16 are diagrams showing a digital single-lens reflex camera as a preferred embodiment of the imaging device of the present invention.

[0115] Fig. 15 is a front perspective view of the camera body 601 as seen from the subject side, showing the state in which the photographing lens unit is removed. Fig. 16 is an exploded perspective view showing a schematic configuration inside the camera, for explaining the peripheral structure of the dust removal device and the imaging unit 400 of the present invention.

[0116] A mirror box 605 is provided within the camera body 601 to which the photographing light beam that has passed through the photographing lens is directed, and a main mirror (quick return mirror) 606 is disposed within the mirror box 605. The main mirror 606 can be held at an angle of 45° with respect to the photographing optical axis to direct the photographing light beam toward a pentagonal roof mirror (not shown), or held in a position away from the photographing light beam to direct it toward an image sensor (not shown).

[0117] On the subject side of main body chassis 300, which forms the framework of the camera body, are arranged, in that order from the subject side, a mirror box 605 and a shutter unit 200. Furthermore, on the photographer side of main body chassis 300, an imaging unit 400 is arranged. Imaging unit 400 is installed such that the imaging surface of the imaging element is spaced a predetermined distance from, and adjusted to be parallel to, the attachment surface of mount section 602, which serves as the reference for attaching the photographing lens unit.

[0118] While a digital single-lens reflex camera has been described as the imaging device of the present invention, it may also be a camera with an interchangeable taking lens unit, such as a mirrorless digital single-lens camera that does not have a mirror box 605. The present invention may also be applied to various imaging devices or electronic devices equipped with imaging devices, such as video cameras with interchangeable taking lens units, copiers, facsimiles, and scanners, which require the removal of dust adhering to the surfaces of optical components. The imaging unit 400 may be used as the image sensor unit of the present invention.

[0119] (ultrasonic probe) The ultrasonic probe of the present invention has the above-described piezoelectric element and transmits and receives signals using the piezoelectric element. By doing so, it is possible to provide an ultrasonic probe having transmission and reception performance equal to or better than that of a piezoelectric element containing lead.

[0120] FIG. 17 is a schematic cross-sectional view showing one embodiment of the ultrasonic probe of the present invention. The ultrasonic probe 1100 in Fig. 17 is composed of piezoelectric elements 1101, a backing material 1102, an acoustic matching layer 1103, and an acoustic lens 1104. As shown in Fig. 17, the multiple piezoelectric elements 1101 are arranged and bonded to the backing material 1102, and an acoustic matching layer 1103 for matching acoustic impedance is provided on the opposite surface, which serves as the transmitting and receiving surface.

[0121] Acoustic matching layer 1103 may be a single layer or multiple layers, preferably two or more layers. Materials that can be used for acoustic matching layer 1103 include, for example, carbon, aluminum, aluminum alloys (e.g., Al-Mg alloys), magnesium alloys, Macor glass, glass, fused silica, copper graphite, polyethylene, polypropylene, polycarbonate, ABC resin, polyphenylene ether, ABS resin, AAS resin, AES resin, nylon, polyamideimide, polyethylene terephthalate, polycarbonate, epoxy resin, and urethane resin.

[0122] The backing material 1102 can be made of thermoplastic resins such as natural rubber, ferrite rubber, epoxy resin, vinyl chloride, polyvinyl butyral, ABS resin, polyurethane, polyvinyl alcohol, polyethylene, polypropylene, polyacetal, polyethylene terephthalate, fluororesin, polyethylene glycol, and polyethylene terephthalate, or these mixed with metal powder, or super-hard materials such as tungsten carbide.

[0123] Piezoelectric element 1101 may be one unit or divided into multiple pieces. FIG. 17 shows an example in which the piezoelectric element is divided into pieces. A flexible cable (not shown) is connected to the electrodes of each piezoelectric element, allowing signals transmitted and received by the piezoelectric element to be input and output. Acoustic lens 1104 is bonded to acoustic matching layer 1103. Acoustic lens 1104 is a component for focusing the ultrasonic waves transmitted from piezoelectric element 1101 toward the subject, and in the example of FIG. 17, it has an arc shape. Note that a rubber containing, for example, a silicone-based resin (rubber) as its main component is commonly used as the material for acoustic lens 1104.

[0124] When using this ultrasonic probe 1100, an alternating voltage is applied to the piezoelectric element 1101 via a flexible cable, vibrating the piezoelectric element through the piezoelectric effect, causing the piezoelectric element 1101 to transmit ultrasonic waves. When the acoustic impedance of the subject to which the ultrasonic waves are applied is low, or when the ultrasonic waves are applied to the subject through water or air, the presence of the acoustic matching layer 1103 can suppress reflected waves caused by large changes in acoustic impedance, allowing the ultrasonic waves to be efficiently emitted to the subject. During reception, ultrasonic waves reflected from inside the subject vibrate the piezoelectric element 1101, and this vibration is converted electrically by the piezoelectric effect to obtain a received signal. During transmission and reception, electrical energy is converted into mechanical energy, and the conversion efficiency depends on the magnitude of the electromechanical coupling coefficient.

[0125] (ultrasound diagnostic equipment) The ultrasonic diagnostic apparatus of the present invention includes at least the ultrasonic probe described above and an image output unit (also referred to as an image display unit). This configuration makes it possible to provide an ultrasonic diagnostic apparatus with drive efficiency equal to or greater than that of a piezoelectric element containing lead. FIG. 18 is a schematic diagram showing one embodiment of the ultrasonic diagnostic apparatus of the present invention. The ultrasonic diagnostic apparatus 1110 of FIG. 18 is composed of an ultrasonic probe 1100, a cable 1111, a drive control unit 1113, an image display unit 1112, and an image processing unit 1114. The flexible cable of the ultrasonic probe 1100 and the drive control unit 1113 are connected by the cable 1111, and an alternating voltage is applied from the drive control unit 1113 to the piezoelectric element 1101 of the ultrasonic probe 1100 via the cable 1111. When ultrasonic waves are irradiated from the ultrasonic probe 1100 into the subject, the ultrasonic waves reflected from inside the subject are converted into electrical signals again by the ultrasonic probe 1100 and input to the image processing unit 1114 via the cable 1111. The image processing unit 1114 generates image data by performing calculations based on the delay time and change in signal intensity relative to the alternating voltage output from the drive control unit 1113. The generated image data is output to the image display unit 1112.

[0126] (Ultrasound diagnostic system) The ultrasonic diagnostic system of the present invention includes the ultrasonic probe described above, a transmitter that transmits signals output from the ultrasonic probe, and a receiver that receives signals transmitted from the transmitter. This configuration provides an ultrasonic diagnostic system with driving efficiency equal to or greater than that of a piezoelectric element containing lead. Figures 19 and 20 are schematic diagrams showing an embodiment of the ultrasonic diagnostic system of the present invention. In the ultrasonic diagnostic system 1120 of Figure 19, signals obtained by the ultrasonic probe 1100 are transmitted from a transmitter 1121 and received by a receiver 1122. Image data is generated from the received signals by an image processor 1114 and output on an image display 1112. The transmitter 1121 and receiver 1122 may be far apart. Transmission and reception may be achieved using wireless communication such as Wi-Fi (registered trademark) or Bluetooth (registered trademark), or via a network line by connecting a network cable. 20, image data is created from the output signal by an image processing unit 1114, and the data is transmitted as a signal from a transmitting unit 1121, which is then received by a receiving unit 1122. The received signal is output by an image display unit 1112.

[0127] (electronic equipment) Next, an electronic device of the present invention will be described. The electronic device of the present invention is equipped with a piezoelectric acoustic component including the above-described piezoelectric element or the above-described laminated piezoelectric element. In this way, it is possible to provide an electronic device with sound generation characteristics equal to or better than those when a piezoelectric element containing lead is used. Piezoelectric acoustic components include speakers, buzzers, microphones, and surface acoustic wave (SAW) elements.

[0128] 21 is an overall perspective view, seen from the front, of a digital camera body 931, which is an example of a preferred embodiment of an electronic device of the present invention. On the front of body 931, optical device 901, microphone 914, strobe light emitting unit 909, and fill light unit 916 are arranged. Microphone 914 is shown with a dashed line because it is built into the body. A hole is provided in front of microphone 914 to pick up sound from outside.

[0129] A power button 933, a speaker 912, a zoom lever 932, and a release button 908 for performing a focusing operation are arranged on the top surface of the main body 931. The speaker 912 is incorporated inside the main body 931 and is indicated by a dashed line. A hole is provided in front of the speaker 912 to transmit sound to the outside.

[0130] The piezoelectric acoustic component of the present invention is used in at least one of the microphone 914, the speaker 912, and the surface acoustic wave element.

[0131] Here, a digital camera has been described as an example of the electronic device of the present invention, but the electronic device of the present invention can also be applied to electronic devices having various piezoelectric acoustic components, such as audio playback devices, audio recording devices, mobile phones, and information terminals.

[0132] As described above, the piezoelectric element of the present invention is suitable for use in ultrasonic motors, optical devices, vibration devices, dust removal devices, imaging devices, ultrasonic probes, ultrasonic diagnostic devices and electronic devices.

[0133] In addition to the above-mentioned devices, the single crystal and piezoelectric element of the present invention can be used in devices such as motors, liquid discharge heads, liquid discharge apparatuses, piezoelectric actuators, piezoelectric sensors, and ferroelectric memories. [Example]

[0134] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. The single crystal and piezoelectric element of the present invention were produced by the following method.

[0135] Example 1 The raw material powders were barium titanate (BaTiO3, Ba / Ti = 0.999) with an average particle size of 100 nm, barium zirconate (BaZrO3, Ba / Zr = 1.002), trimanganese tetroxide (Mn3O4), and titanium oxide, which was used to adjust the ratio a of the sum of the moles of Ti and Zr to the sum of the moles of Ba. These raw material powders were mixed with a composition formula Ba, which is mainly composed of titanium and barium. 0.985 (Ti 0.93 , Zr 0.07 )O3 ratio. Mn was added so that the content was 0.12 parts by mass in terms of metal per 100 parts by mass of this oxide. Furthermore, this oxide to which Mn had been added was dry mixed for 24 hours using a ball mill. To granulate the resulting mixed powder, 3 parts by mass of PVA binder was attached to the surface of the mixed powder using a spray dryer.

[0136] Next, the obtained granulated powder was filled into a mold with a mirror-finished surface facing the sample, and a molding pressure of 200 MPa was applied using a press molding machine to produce two rectangular parallelepiped molded bodies. These molded bodies may be further compressed using a cold isostatic pressing machine.

[0137] Next, one of the above molded bodies was placed on a microscope heating stage (manufactured by LINKAM) and heated, and the surface of the matrix 12 was observed under a microscope.The liquid phase start temperature was 1320°C and the liquid phase end temperature was 1385°C.

[0138] Next, the other molded body was placed in an electric furnace and held at a maximum temperature of 1300°C for 5 hours, and then sintered in an air atmosphere for a total of 24 hours to obtain a matrix 12 having a rectangular parallelepiped shape and dimensions of 12 mm x 18 mm x 1.3 mm.

[0139] Next, the obtained rectangular parallelepiped matrix was polished on both sides using a polishing machine while changing the grit size of the abrasive grains to a thickness of 1.0 mm, and finally chemical polishing was performed as a finishing step to obtain a mirror surface.

[0140] Next, a zirconia-coated alumina sagger was prepared as sagger 17, a zirconia setter as setter 16, a zirconia setter (50 mm x 50 mm x 1 mm, weighing 20 g) as weight 14, and zirconia beads as beads 15. These were arranged as shown in Figure 6, and placed in an electric furnace with lid 18 closed as shown in Figure 7, and fired.

[0141] The seed single crystal 11 used here was a 10 mm x 10 mm x 1 mm BaTiO3 (manufactured by Physcience Opto-electronics) substrate with both the main and side surfaces being (100) planes, and both surfaces were mirror-polished. The temperature profile during firing was as follows: in the first heating step, the temperature was raised from room temperature to 1320°C, the liquid phase start temperature, at a rate of 150°C / h over 8.8 hours; then in the second heating step, the temperature was raised from 1320°C to 1385°C, the liquid phase end temperature, at a rate of 0.65°C / h over 100 hours. The firing step then involved holding the temperature at 1385°C for 300 hours, and finally cooling it down to room temperature. The first heating step, second heating step, and firing step were all carried out in air. When the matrix after firing was observed under an optical microscope, it was confirmed that the single crystal growth portion (the region extending from the seed single crystal) was a single crystal without grain boundaries.

[0142] Next, the seed single crystal 11 portion was removed by polishing, and the single crystal portion was cut out with a dicing saw to obtain a first single crystal.

[0143] Next, the crystal structure of the first single crystal was analyzed by X-ray diffraction, and only a peak corresponding to a perovskite-type (100) oriented single crystal was observed.

[0144] Next, the first single crystal was placed on a setter 6 made of stabilized zirconia as shown in Figure 2, and placed in a high-temperature electric furnace of the reducing and firing furnace shown in Figure 1, where it was fired at 1340°C for 5 hours in a reducing atmosphere, and finally cooled to room temperature by standing. The reducing atmosphere gas used was argon containing 3 mol% hydrogen in a gas cylinder, and the oxygen partial pressure immediately before firing was 5 × 10 ―15 It was Pa.

[0145] Next, the crystal structure of the single crystals fired in a reducing atmosphere was analyzed by X-ray diffraction. As a result, no heterophases, or crystals different from perovskite, were observed. Next, the first single crystal 1 fired in a reducing atmosphere was placed in a sagger 7 as shown in Figure 3, placed on a setter 6 made of stabilized zirconia, covered, placed in an electric furnace, and fired in an air atmosphere at 1000°C for 10 hours, and finally cooled to room temperature to obtain a single crystal. A super electric furnace SSFT-1520 (manufactured by Yamada Denki Co., Ltd.) was used for firing.

[0146] Next, the crystal structure of the obtained single crystal was analyzed by X-ray diffraction. The results are shown in Figure 22. From the (110) pole figure and the (200) pole figure, it was observed that the crystal was (100) oriented. The side surface of the sample was also a (200) plane.

[0147] Next, the composition of the obtained single crystal was evaluated by ICP emission spectroscopy. The results are shown in Table 1. The weighed composition of Ba, Ti, Zr, and Mn matched the composition after firing. Furthermore, no Pb was detected.

[0148] Next, the single crystal was processed into a 0.8 mm x 0.8 mm x 5.0 mm square pillar by polishing and dicing, with the crystal orientation of the 0.8 mm x 0.8 mm face being (100). Next, gold electrodes with a thickness of 400 nm were formed on both sides of the 0.8 mm x 0.8 mm substrate by DC sputtering, thereby producing a piezoelectric element of the present invention. A 30 nm titanium film was formed between the electrode and the single crystal as an adhesive layer. The 0.8 mm × 5.0 mm side surface was masked during DC sputtering to prevent the gold electrode from adhering.

[0149] Next, the surface of a hot plate was set to a temperature of 60° C. to 100° C., and an electric field of 1 kV / mm was applied to the obtained piezoelectric element on the hot plate for 30 minutes, thereby performing a polarization treatment. Next, the electromechanical coupling coefficient k of the piezoelectric element having the single crystal of the present invention 33 was evaluated at room temperature (25°C) by a resonance-antiresonance method using an impedance analyzer (4294A manufactured by Agilent Technologies). As a result of the evaluation, the electromechanical coupling coefficient k 33 The electromechanical coupling coefficient was 83%, which was found to be a large value for a lead-free piezoelectric material. Next, the temperature of the sample was changed from 0°C to 70°C at a rate of 0.5°C per minute while measuring in 5°C increments, and the variation rate of the piezoelectric constant d and the relative dielectric constant ε in the temperature range from 0°C to 70°C were measured. 33 The maximum value of was derived according to the following equations (5) and (6).

number

number

[0150] Next, the coercive electric field of the piezoelectric element was evaluated. Using a ferroelectric / piezoelectric evaluation system (LCII manufactured by Radiant Technologies, Inc.), the electric field at zero polarization was read from the PE hysteresis curve obtained from the polarization versus electric field in the hysteresis measurement mode of Figure 24, and this value was taken as the coercive electric field. The coercive electric field at this time was 4.0 kV / cm.

[0151] Example 2 As shown in Table 1, the single crystal and piezoelectric element of the present invention were obtained in the same manner as in Example 1, except that the temperature for firing in a reducing atmosphere was set to 1385°C. Subsequently, in the same process as in Example 1, the composition of the single crystal of the present invention and the electromechanical coupling coefficient k 33 The coercive electric field, the maximum value of the relative dielectric constant at 0° C. to 70° C., and the rate of change of the piezoelectric constant were evaluated. The results are shown in Table 1.

[0152] Example 3 The raw material powders were barium titanate (BaTiO3, Ba / Ti=0.999) with an average particle size of 100 nm, barium zirconate (BaZrO3, Ba / Zr=1.002), trimanganese tetroxide (Mn3O4), bismuth oxide (Bi2O3), lithium carbonate (Li2CO3), and titanium oxide was used to adjust the ratio a of the sum of the moles of Ti and Zr to the sum of the moles of Ba. These raw material powders were mixed together in a composition formula Ba, which is mainly composed of titanium and barium. 0.990 (Ti 0.98 ,Zr 0.02 )O3 ratio was measured.

[0153] To 100 parts by mass of this oxide, trimanganese tetroxide (Mn3O4), bismuth oxide (Bi2O3), and lithium carbonate (Li2CO3) were added so that the Mn content was 0.23 parts by mass (metal equivalent), the Bi content was 0.18 parts by mass (metal equivalent), and the Li content was 0.15 parts by mass (metal equivalent). Furthermore, the oxides to which Mn3O4, Bi2O3, and Li2CO3 had been added were dry mixed using a ball mill for 24 hours. To granulate the resulting mixed powder, 3 parts by mass of PVA binder was attached to the surface of the mixed powder using a spray dryer, resulting in granulated powder.

[0154] Next, the obtained granulated powder was filled into a mold with a mirror-finished surface facing the sample, and a molding pressure of 200 MPa was applied using a press molding machine to produce two rectangular parallelepiped molded bodies. These molded bodies may be further compressed using a cold isostatic pressing machine.

[0155] Next, one of the above molded bodies was placed on a microscope heating stage (manufactured by LINKAM) and heated, and the surface of the matrix 12 was observed under a microscope.The liquid phase start temperature was 1320°C and the liquid phase end temperature was 1400°C.

[0156] Next, the other molded body was placed in an electric furnace and held at a maximum temperature of 1300°C for 5 hours, and then sintered in an air atmosphere for a total of 24 hours to obtain a matrix 12 having a rectangular parallelepiped shape and dimensions of 12 mm x 18 mm x 1.3 mm.

[0157] Next, the obtained rectangular parallelepiped matrix was polished on both sides using a polishing machine while changing the grit size of the abrasive grains to a thickness of 1.0 mm, and finally chemical polishing was performed as a finishing step to obtain a mirror surface.

[0158] Next, a zirconia-coated alumina sagger was prepared as sagger 17, a zirconia setter as setter 16, a zirconia setter (50 mm x 50 mm x 1 mm, weighing 20 g) as weight 14, and zirconia beads as beads 15. These were arranged as shown in Figure 6, and placed in an electric furnace with lid 18 closed as shown in Figure 7, and fired.

[0159] The seed single crystal 11 used here was a 10 mm x 10 mm x 1 mm BaTiO3 (manufactured by Physcience Opto-electronics) substrate with both the main and side surfaces being (110) planes, and both surfaces were mirror-polished. The temperature profile during firing was as follows: in the first heating step, the temperature was raised from room temperature to 1320°C, the liquid phase start temperature, at a rate of 150°C / h over 8.8 hours; then in the second heating step, the temperature was raised from 1320°C to 1400°C, the liquid phase end temperature, at a rate of 0.80°C / h over 100 hours. The firing step then involved holding the temperature at 1400°C for 1000 hours, and finally cooling it down to room temperature. The first heating step, second heating step, and firing step were carried out in air. When the matrix after firing was observed under an optical microscope, it was confirmed that the single crystal growth portion (the region extending from the seed single crystal) was a single crystal without grain boundaries.

[0160] Next, the seed single crystal 11 portion was removed by polishing, and the single crystal portion was cut out with a dicing saw to obtain a first single crystal.

[0161] Next, the crystal structure of the first single crystal was analyzed by X-ray diffraction, and only peaks corresponding to the perovskite-type (110) oriented single crystal were observed.

[0162] Next, the first single crystal was placed on a setter 6 made of stabilized zirconia as shown in Figure 2, and placed in a high-temperature electric furnace of the reduction firing furnace shown in Figure 1, where it was fired at 1280°C for 5 hours in a reducing atmosphere, and finally cooled to room temperature by standing. The reducing atmosphere gas used was argon containing 3 mol% hydrogen in a gas cylinder, and the oxygen partial pressure immediately before firing was 5 × 10 ―10 It was Pa.

[0163] Next, the crystal structure of the single crystals fired in a reducing atmosphere was analyzed by X-ray diffraction. As a result, no heterophases, or crystals different from perovskite, were observed. Next, the first single crystal 1 fired in a reducing atmosphere was placed in a sagger 7 as shown in Figure 3, placed on a setter 6 made of stabilized zirconia, covered, placed in an electric furnace, and fired in an air atmosphere at 1000°C for 10 hours, and finally cooled to room temperature to obtain a single crystal. A super electric furnace SSFT-1520 (manufactured by Yamada Denki Co., Ltd.) was used for firing.

[0164] Next, the crystal structure of the obtained single crystal was analyzed by X-ray diffraction. The results are shown in Figure 23. From the (110) pole figure and the (200) pole figure, it was observed that the crystal was (110) oriented.

[0165] Next, the composition of the obtained single crystal was evaluated by ICP emission spectroscopy. The results are shown in Table 1. The weighed composition of Ba, Ti, Zr, Mn, and Bi matched the composition after firing. Furthermore, no Pb was detected.

[0166] Next, the single crystal was processed into a 0.8 mm x 0.8 mm x 5.0 mm square pillar by polishing and dicing, with the crystal orientation of the 0.8 mm x 0.8 mm face being (110). Next, gold electrodes with a thickness of 400 nm were formed on both sides of the 0.8 mm x 0.8 mm substrate by DC sputtering, thereby producing a piezoelectric element of the present invention. A 30 nm titanium film was formed between the electrode and the single crystal as an adhesive layer. The 0.8 mm × 5.0 mm side surface was masked during DC sputtering to prevent the gold electrode from adhering.

[0167] Next, the surface of a hot plate was set to a temperature of 60° C. to 100° C., and an electric field of 1 kV / mm was applied to the obtained piezoelectric element on the hot plate for 30 minutes, thereby performing a polarization treatment. Next, the electromechanical coupling coefficient k of the piezoelectric element having the single crystal of the present invention 33 was evaluated at room temperature (25°C) by a resonance-antiresonance method using an impedance analyzer (4294A manufactured by Agilent Technologies). As a result of the evaluation, the electromechanical coupling coefficient k 33 The electromechanical coupling coefficient was 82%, which was found to be a large value for a lead-free piezoelectric material. Next, the temperature of the sample was changed from 0°C to 70°C at a rate of 0.5°C per minute while measuring in 5°C increments, and the variation rate of the piezoelectric constant d and the relative dielectric constant ε in the temperature range from 0°C to 70°C were measured. 33 The maximum value of was derived according to the above equations (5) and (6). These results are shown in Table 1 and Figures 25 and 26. T is the dielectric constant, and the relative permittivity is the dielectric constant divided by the dielectric constant of a vacuum. As a single crystal, d 33 The fluctuation of the relative permittivity ε 33 The maximum value was small.

[0168] Next, the coercive electric field of the piezoelectric element was evaluated. Using a ferroelectric / piezoelectric evaluation system (LCII manufactured by Radiant Technologies, Inc.), the electric field at zero polarization was read from the PE hysteresis curve obtained from the polarization versus electric field in the hysteresis measurement mode of Figure 24, and this value was taken as the coercive electric field. The coercive electric field at this time was 7.5 kV / cm.

[0169] (Comparative Example 1) The raw material powders were barium titanate (BaTiO3, Ba / Ti=0.999) with an average particle size of 100 nm, barium zirconate (BaZrO3, Ba / Zr=1.002), trimanganese tetroxide (Mn3O4), and titanium oxide to adjust the ratio a of the sum of the moles of Ti and Zr to the sum of the moles of Ba. These raw material powders were prepared using the composition formula Ba, which is mainly composed of titanium and barium. 0.985 (Ti 0.93 , Zr 0.07 )O3 ratio. Mn was added so that the content was 0.12 parts by mass in terms of metal per 100 parts by mass of this oxide. Furthermore, this oxide to which Mn had been added was dry mixed for 24 hours using a ball mill. To granulate the resulting mixed powder, 3 parts by mass of PVA binder was attached to the surface of the mixed powder using a spray dryer.

[0170] Next, the obtained granulated powder was filled into a mold whose surface facing the sample had been mirror-finished, and a molding pressure of 200 MPa was applied using a press molding machine to produce two rectangular solid-shaped molded bodies.

[0171] Next, one of the above molded bodies was placed on a microscope heating stage (manufactured by LINKAM) and heated, and the surface of the matrix 12 was observed under a microscope.The liquid phase start temperature was 1320°C and the liquid phase end temperature was 1385°C.

[0172] Next, the other molded body was placed in an electric furnace and held at a maximum temperature of 1300°C for 5 hours, and then sintered in an air atmosphere for a total of 24 hours to obtain a matrix 12 having a rectangular parallelepiped shape and dimensions of 12 mm x 18 mm x 1.3 mm.

[0173] Next, both sides of the obtained rectangular parallelepiped matrix 12 were polished using a polishing machine while changing the grit size of the abrasive grains to a thickness of 1.0 mm, and finally chemical polishing was performed as a finishing step to obtain a mirror surface.

[0174] Next, a zirconia-coated alumina sagger was prepared as sagger 17, a zirconia setter as setter 16, a zirconia setter (50 mm x 50 mm x 1 mm, weighing 20 g) as weight 14, and zirconia beads as beads 15. These were arranged as shown in Figure 6, and placed in an electric furnace with the lid on as shown in Figure 7, and fired. The seed single crystal 11 used here was a 10 mm x 10 mm x 1 mm BaTiO3 (manufactured by Physcience Opto-electronics) substrate with the top, bottom and side surfaces all being (100) planes, and both surfaces were mirror polished.

[0175] The temperature profile during firing was as follows: in the first heating step, the temperature was raised from room temperature to 1320°C, the liquid phase start temperature, at a rate of 150°C / h over 8.8 hours; then in the second heating step, the temperature was raised from 1320°C to 1385°C, the liquid phase end temperature, at a rate of 0.65°C / h over 100 hours. The firing step then involved holding the temperature at 1385°C for 300 hours, and finally cooling it down to room temperature. The first heating step, second heating step, and firing step were all carried out in air. When the matrix 12 after firing was observed with an optical microscope, it was confirmed that the single crystal growth portion (the region extending from the seed single crystal) was a single crystal without grain boundaries.

[0176] Next, the seed single crystal 11 portion was removed by polishing, and the single crystal portion was cut out with a dicing saw, thereby obtaining the single crystal of Comparative Example 1. Next, the crystal structure of the obtained single crystal was analyzed by X-ray diffraction. The (110) and (200) pole figures showed a (100) orientation. The side surface of the sample was also a (200) plane.

[0177] Next, the composition of the obtained single crystal was evaluated by ICP emission spectroscopy. The results are shown in Table 1. The weighed composition of Ba, Ti, Zr, and Mn matched the composition after firing. Furthermore, no Pb was detected.

[0178] Next, the single crystal was processed into a 0.8 mm x 0.8 mm x 5.0 mm square pillar by polishing and dicing, with the crystal orientation of the 0.8 mm x 0.8 mm face being (100). Next, gold electrodes with a thickness of 400 nm were formed on both sides of the 0.8 mm×0.8 mm substrate by DC sputtering, thereby producing a piezoelectric element of Comparative Example 1. A 30 nm titanium film was formed between the electrode and the single crystal as an adhesive layer. The 0.8 mm × 5.0 mm side surface was masked during DC sputtering to prevent the gold electrode from adhering. Next, the surface of a hot plate was set to a temperature of 60° C. to 100° C., and an electric field of 1 kV / mm was applied to the obtained piezoelectric element on the hot plate for 30 minutes, thereby performing a polarization treatment.

[0179] Next, the electromechanical coupling coefficient k of the piezoelectric element having the single crystal of Comparative Example 1 33 was evaluated at room temperature (25°C) by a resonance-antiresonance method using an impedance analyzer (4294A manufactured by Agilent Technologies). As a result of the evaluation, the k 33 was 79%.

[0180] Next, the temperature of the sample was changed from 0°C to 70°C at a rate of 0.5°C per minute, and measurements were taken in 5°C increments. The piezoelectric constant d 33 Fluctuation rate of and relative permittivity ε 33 The maximum value of was derived according to the above equations (5) and (6). These results are shown in Table 1. T is the dielectric constant, and the relative permittivity is the dielectric constant divided by the dielectric constant of a vacuum. Next, the coercive electric field of the piezoelectric element was evaluated. Using a ferroelectric / piezoelectric evaluation system (LCII manufactured by Radiant Technologies, Inc.), the electric field at zero polarization was read from the PE hysteresis curve obtained from the polarization amount against the electric field, and this value was taken as the coercive electric field. The coercive electric field at this time was 1.6 kV / cm.

[0181] (Comparative Example 2) The raw material powders were barium titanate (BaTiO3, Ba / Ti=0.999) with an average particle size of 100 nm, barium zirconate (BaZrO3, Ba / Zr=1.002), trimanganese tetroxide (Mn3O4), bismuth oxide (Bi2O3), lithium carbonate (Li2CO3), and titanium oxide was used to adjust the ratio a of the sum of the moles of Ti and Zr to the sum of the moles of Ba. These raw material powders were mixed together in a composition formula Ba, which is mainly composed of titanium and barium. 0.990 (Ti 0.98 ,Zr 0.02 )O3 ratio was measured. To 100 parts by mass of this oxide, trimanganese tetroxide (Mn3O4), bismuth oxide (Bi2O3), and lithium carbonate (Li2CO3) were added so that the Mn content was 0.23 parts by mass (metal equivalent), the Bi content was 0.18 parts by mass (metal equivalent), and the Li content was 0.15 parts by mass (metal equivalent). Furthermore, the oxides to which Mn3O4, Bi2O3, and Li2CO3 had been added were dry mixed using a ball mill for 24 hours. To granulate the resulting mixed powder, 3 parts by mass of PVA binder was attached to the surface of the mixed powder using a spray dryer, resulting in granulated powder.

[0182] Next, the obtained granulated powder was filled into a mold whose surface facing the sample had been mirror-finished, and a molding pressure of 200 MPa was applied using a press molding machine to produce two rectangular solid-shaped molded bodies.

[0183] Next, one of the above molded bodies was placed on a microscope heating stage (manufactured by LINKAM) and heated, and the surface of the matrix 12 was observed under a microscope.The liquid phase start temperature was 1320°C and the liquid phase end temperature was 1400°C.

[0184] Next, the other molded body was placed in an electric furnace and held at a maximum temperature of 1300°C for 5 hours, and then sintered in an air atmosphere for a total of 24 hours to obtain a matrix 12 having a rectangular parallelepiped shape and dimensions of 12 mm x 18 mm x 1.3 mm.

[0185] Next, both sides of the obtained rectangular parallelepiped matrix 12 were polished using a polishing machine while changing the grit size of the abrasive grains to a thickness of 1.0 mm, and finally chemical polishing was performed as a finishing step to obtain a mirror surface.

[0186] Next, a zirconia-coated alumina sagger was prepared as sagger 17, a zirconia setter as setter 16, a zirconia setter (50 mm x 50 mm x 1 mm, weighing 20 g) as weight 14, and zirconia beads as beads 15. These were arranged as shown in Figure 6, and placed in an electric furnace with the lid on as shown in Figure 7, and fired. The seed single crystal 11 used here was a 10 mm x 10 mm x 1 mm BaTiO3 (manufactured by Physcience Opto-electronics) substrate with the top, bottom and side surfaces all being (100) planes, and both surfaces were mirror polished.

[0187] The temperature profile during firing was as follows: in the first heating step, the temperature was raised from room temperature to 1320°C, the liquid phase start temperature, at a rate of 150°C / h over 8.8 hours; then in the second heating step, the temperature was raised from 1320°C to 1400°C, the liquid phase end temperature, at a rate of 0.80°C / h over 100 hours. The firing step then involved holding the temperature at 1400°C for 1000 hours, and finally cooling it down to room temperature. The first heating step, second heating step, and firing step were carried out in air. When the matrix 12 after firing was observed with an optical microscope, it was confirmed that the single crystal growth portion (the region extending from the seed single crystal) was a single crystal without grain boundaries.

[0188] Next, the seed single crystal 11 portion was removed by polishing, and the single crystal portion was cut out with a dicing saw, thereby obtaining a single crystal of Comparative Example 2.

[0189] Next, the crystal structure of the obtained single crystal was analyzed by X-ray diffraction. From the (110) and (200) pole figures, it was observed that the crystal was (110) oriented.

[0190] Next, the composition of the obtained single crystal was evaluated by ICP emission spectroscopy. The results are shown in Table 1. The weighed composition of Ba, Ti, Zr, Mn, and Bi matched the composition after firing. Furthermore, no Pb was detected.

[0191] Next, the single crystal was processed into a 0.8 mm x 0.8 mm x 5.0 mm square pillar by polishing and dicing, with the crystal orientation of the 0.8 mm x 0.8 mm face being (110). Next, gold electrodes with a thickness of 400 nm were formed on both sides of the 0.8 mm×0.8 mm substrate by DC sputtering, thereby producing a piezoelectric element of Comparative Example 2. A 30 nm titanium film was formed between the electrode and the single crystal as an adhesive layer. The 0.8 mm × 5.0 mm side surface was masked during DC sputtering to prevent the gold electrode from adhering. Next, the surface of a hot plate was set to a temperature of 60° C. to 100° C., and an electric field of 1 kV / mm was applied to the obtained piezoelectric element on the hot plate for 30 minutes, thereby performing a polarization treatment.

[0192] Next, the electromechanical coupling coefficient k of the piezoelectric element having the single crystal of Comparative Example 2 33 was evaluated at room temperature (25°C) by a resonance-antiresonance method using an impedance analyzer (4294A manufactured by Agilent Technologies). As a result of the evaluation, the k 33 was 75%.

[0193] Next, the temperature of the sample was changed from 0°C to 70°C at a rate of 0.5°C per minute, and measurements were taken in 5°C increments. The piezoelectric constant d 33 Fluctuation rate of and relative permittivity ε 33 The maximum value of was derived according to the above equations (5) and (6). These results are shown in Table 1. T is the dielectric constant, and the relative permittivity is the dielectric constant divided by the dielectric constant of a vacuum. Next, the coercive electric field of the piezoelectric element was evaluated. Using a ferroelectric / piezoelectric evaluation system (LCII manufactured by Radiant Technologies, Inc.), the electric field at zero polarization was read from the PE hysteresis curve obtained from the polarization amount against the electric field, and this value was taken as the coercive electric field. The coercive electric field at this time was 5.6 kV / cm.

[0194] [Table 1]

[0195] Example 4 An ultrasonic motor shown in Fig. 9 was fabricated using the piezoelectric element of Example 1. Rotation of the fabricated ultrasonic motor in response to application of an alternating voltage was confirmed.

[0196] Example 5 The optical device shown in Fig. 11 was fabricated using the ultrasonic motor of Example 4. In the fabricated optical device, autofocus operation in response to application of an alternating voltage was confirmed.

[0197] Example 6 12A and 12B was fabricated using the piezoelectric element of Example 1. When plastic beads were scattered in the fabricated dust removal device and an alternating voltage was applied, a good dust removal rate was confirmed.

[0198] Example 7 The imaging device shown in Fig. 15 was fabricated using the dust removal device of Example 6. When the fabricated imaging device was operated, dust on the surface of the imaging unit was successfully removed, and an image without dust defects was obtained.

[0199] Example 8 The ultrasonic probe shown in Fig. 17 was fabricated using the piezoelectric element of Example 1. In the fabricated ultrasonic probe, ultrasonic waves were transmitted by applying an alternating voltage, and a received signal due to reflection from inside the subject was confirmed.

[0200] Example 9 The ultrasonic probe of Example 7 was used to fabricate the ultrasonic diagnostic device shown in Fig. 18. When the fabricated ultrasonic diagnostic device was operated, a clear image of the inside of the subject was output.

[0201] Example 10 An ultrasonic diagnostic system shown in Fig. 19 was fabricated using the ultrasonic probe of Example 8. When the fabricated ultrasonic diagnostic system was operated and an image was displayed on the image display unit, a clear image of the inside of the subject was output.

[0202] Example 11 An electronic device shown in Fig. 21 was fabricated using the piezoelectric element of Example 1. In the fabricated electronic device, speaker operation in response to application of an alternating voltage was confirmed. [Industrial Applicability]

[0203] The single crystal of the present invention has a large mechanical quality factor and a large coercive field, and therefore can be used without problems in many devices such as ultrasonic motors, dust removal devices, and ultrasonic probes.

[0204] The disclosure of this embodiment includes the following methods and configurations. [Method 1] A method for producing a perovskite single crystal, comprising: A step (1) of obtaining a first perovskite single crystal by firing a raw material containing an acceptor in an air atmosphere; A method for producing a perovskite-type single crystal, characterized in that a single crystal having a higher coercive field value than the first single crystal is obtained by sequentially carrying out step (2), which includes a step of firing the first single crystal in a reducing atmosphere, and step (3), which includes a step of firing the single crystal obtained in step (2) in an air atmosphere. [Method 2] 2. The method for producing a perovskite single crystal according to Method 1, wherein the acceptor is Mn. [Method 3] The method for producing a perovskite-type single crystal according to Method 1 or 2, wherein the firing temperature in the step (2) of firing in a reducing atmosphere is equal to or lower than the firing temperature in the step (1) of obtaining the first single crystal. [Method 4] The method for producing a perovskite single crystal according to any one of Methods 1 to 3, wherein the firing temperature in the step (3) of firing in an air atmosphere is equal to or lower than the firing temperature in the step (2) of firing in a reducing atmosphere. [Method 5] 5. The method for producing a perovskite single crystal according to any one of Methods 1 to 4, wherein the raw material contains Ba, Ti, and Zr. [Method 6] 6. The method for producing a perovskite-type single crystal according to any one of Methods 1 to 5, wherein the step of obtaining the first single crystal in step (1) is a solid phase growth method. [Method 7] 7. The method for producing a perovskite single crystal according to any one of Methods 1 to 6, wherein the raw material contains an oxide containing Ba, Ti, and Zr, and Mn, wherein x, which is a molar ratio of Zr to the sum of the Ti and Zr, is 0.02≦x≦0.13, and the content of Mn, calculated as metal, is 0.04 parts by mass or more and 0.36 parts by mass or less per 100 parts by mass of the oxide. [Method 8] the raw material contains an oxide containing Ba, Ti, and Zr, and Mn, Bi, and Li; The method for producing a perovskite-type single crystal according to any one of Methods 1 to 6, wherein x, which is a molar ratio of Zr to the sum of Ti and Zr, is 0.02≦x≦0.13, the Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide, the Bi content is more than 0 parts by mass and 0.20 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide, and the Li content is 0.05 parts by mass or more and 0.20 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide. [Method 9] The reducing atmosphere in the step (2) is a gas containing argon and hydrogen, and the oxygen partial pressure P(O2) is 1×10 ―10 9. The method for producing a perovskite single crystal according to any one of Methods 1 to 8, wherein the pressure is 0.1 Pa or less. [Method 10] 10. The method for producing a perovskite-type single crystal according to any one of Methods 1 to 9, wherein the firing temperature in the step (2) of firing under a reducing atmosphere is 1340° C. or higher. [Method 11] 11. The method for producing a perovskite-type single crystal according to any one of Methods 1 to 10, wherein the firing temperature in the step (3) of firing in an air atmosphere is 1000° C. or lower. [Configuration 1] A single crystal containing an oxide having a perovskite structure containing Ba, Ti, and Zr, and Mn, x, which is a molar ratio of the Zr to the sum of the Ti and the Zr, is 0.02≦x≦0.13; the Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, The single crystal may contain Bi, and the content of Bi is 0 parts by mass or more and 0.20 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, The electromechanical coupling coefficient k of the single crystal at 25°C 33 A perovskite-type single crystal characterized in that the ratio of the SiO2 content to the SiO2 content is 80% or more and the coercive field is 2.5 kV / cm or more. [Configuration 2] 2. The perovskite-type single crystal according to claim 1, wherein the single crystal contains less than 1000 ppm of Pb. [Configuration 3] The piezoelectric constant d of the single crystal is expressed by the following formula (1): 33 3. The perovskite single crystal according to aspect 1 or 2, wherein the fluctuation range (%) of is 65% or less. 100×Δd 33@0℃~70℃ / d 33@0℃ (1) [Configuration 4] The dielectric constant ε of the single crystal in the range of 0°C to 70°C 33 4. The perovskite single crystal according to any one of aspects 1 to 3, wherein the maximum value of is 6,500 or less. [Configuration 5] The dielectric constant ε of the single crystal in the range of 0°C to 60°C 33 4. The perovskite single crystal according to any one of aspects 1 to 3, wherein the maximum value of is 4,200 or less. [Configuration 6] 6. A piezoelectric element having a plurality of electrodes and a single crystal, wherein the single crystal is the single crystal according to any one of configurations 1 to 5. [Configuration 7] An ultrasonic motor comprising at least a vibrating body provided with the piezoelectric element according to configuration 6, and a moving body in contact with the vibrating body. [Configuration 8] 10. An optical device comprising the ultrasonic motor according to aspect 7 in a drive section. [Configuration 9] A vibration device comprising a vibrating body having the piezoelectric element according to configuration 6 arranged on a vibration plate. [Configuration 10] A dust removing device comprising the vibrating device according to aspect 9 in a vibrating section. [Configuration 11] 11. An imaging device comprising at least the dust removal device according to configuration 10 and an imaging element unit, wherein the diaphragm of the dust removal device is provided on the light receiving surface side of the imaging element unit. [Configuration 12] An ultrasonic probe having the piezoelectric element according to configuration 6, wherein the piezoelectric element transmits and receives ultrasonic waves. [Configuration 13] 13. An ultrasonic diagnostic apparatus comprising at least the ultrasonic probe according to claim 12 and an image output unit. [Configuration 14] 13. An ultrasound diagnostic system comprising: the ultrasound probe according to claim 12; a transmitter that transmits a signal output from the ultrasound probe; and a receiver that receives the signal transmitted from the transmitter. [Configuration 15] 10. An electronic device comprising a piezoelectric acoustic component having the piezoelectric element according to claim 6. [Explanation of symbols]

[0205] 1. First single crystal 2. Reducing atmosphere firing furnace 3. High-temperature electric furnace 4 gas cylinders 5 Oxygen Partial Pressure Controller 6 Setta 7. Sack Bowl 11 seed single crystals 12 Matrix 14 Weight 15 beads 16 Setta 17 Sack Bowl 18 Lid 21 First electrode 22 Single crystal section 23 Second electrode 201 Oscillator 202 Rotor 203 Output shaft 2011 Elastic Ring 2012 Piezoelectric element 2013 Organic adhesives 310 Dust removal equipment 320 diaphragm 330 Piezoelectric element 331 Single Crystal 332 First electrode 333 Second Electrode 336 First electrode surface 337 Second electrode surface 601 Camera body 602 Mounting section 605 Mirror Box 606 Main mirror 200 shutter unit 300 main chassis 400 Imaging unit 701 Front lens group 702 Rear lens group (focus lens) 711 Detachable Mount 712 Fixed tube 713 Straight guide tube 714 Front group lens barrel 715 Cam ring 716 Rear lens barrel 717 Cam Roller 718 Axial screw 719 Laura 720 Rotation Transmission Ring 722 Koro 724 Manual Focus Ring 725 Ultrasonic Motor 726 Wave washer 727 Ball Race 728 Focus Key 729 Joint Materials 732 Washer 733 Low Friction Sheet 901 Optical equipment 908 release button 909 Strobe light emitting part 912 Speaker 914 Mike 916 Auxiliary light section 931 Main Unit 932 Zoom Lever 33 Power button 1100 Ultrasound Probe 1101 Piezoelectric element 1102 Backing material 1103 Acoustic matching layer 1104 Acoustic Lens 1110 Ultrasound diagnostic equipment 1111 Cable 1112 Image display unit 1113 Drive control unit 1114 Image processing unit 1120 Ultrasound Diagnostic System 1121 Transmitter 1122 Receiver

Claims

1. A method for producing a perovskite single crystal, comprising: A step (1) of obtaining a first perovskite single crystal by firing a raw material containing an acceptor in an air atmosphere; Step (2) comprising a step of firing the first single crystal in a reducing atmosphere; A method for producing a perovskite-type single crystal, characterized in that a single crystal having a higher coercive field value than the first single crystal is obtained by sequentially passing through step (3), which includes a step of firing the single crystal obtained in step (2) in an air atmosphere.

2. 2. The method for producing a perovskite single crystal according to claim 1, wherein the acceptor is Mn.

3. 2. The method for producing a perovskite-type single crystal according to claim 1, wherein the firing temperature in the step (2) of firing in a reducing atmosphere is equal to or lower than the firing temperature in the step (1) of obtaining the first single crystal.

4. 2. The method for producing a perovskite single crystal according to claim 1, wherein the firing temperature in the step (3) of firing in an air atmosphere is equal to or lower than the firing temperature in the step (2) of firing in a reducing atmosphere.

5. 2. The method for producing a perovskite single crystal according to claim 1, wherein the raw material contains Ba, Ti, and Zr.

6. 2. The method for producing a perovskite-type single crystal according to claim 1, wherein the step (1) for obtaining the first single crystal is a solid phase growth method.

7. the raw material contains an oxide containing Ba, Ti, and Zr, and Mn, and x, which is a molar ratio of Zr to the sum of the Ti and the Zr, is 0.02≦x≦0.13; In terms of metal, per 100 parts by mass of the oxide, The Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less. A method for producing the perovskite single crystal according to claim 1.

8. the raw material contains an oxide containing Ba, Ti, and Zr, and Mn, Bi, and Li; 2. The method for producing a perovskite-type single crystal according to claim 1, wherein x, a molar ratio of Zr to the sum of Ti and Zr, is 0.02≦x≦0.13, the Mn content is 0.04 parts by mass or more and 0.36 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide, the Bi content is more than 0 parts by mass and 0.20 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide, and the Li content is 0.05 parts by mass or more and 0.20 parts by mass or less, calculated as a metal relative to 100 parts by mass of the oxide.

9. The reducing atmosphere in the step (2) is a gas containing argon and hydrogen, and the oxygen partial pressure P(O ２ ) is 1 x 10 ―１０ The method for producing a perovskite single crystal according to claim 1, wherein the temperature is 1000 K or less.

10. The firing temperature in the step (2) of firing under a reducing atmosphere is 1280°C or higher. A method for producing the perovskite single crystal according to claim 1.

11. The firing temperature in the step (3) of firing under an air atmosphere is 1000°C or less. A method for producing the perovskite single crystal according to claim 1.

12. A single crystal containing an oxide having a perovskite structure containing Ba, Ti, and Zr, and Mn, x, which is a molar ratio of the Zr to the sum of the Ti and the Zr, is 0.02≦x≦0.13; The content of Mn is 0.04 parts by mass or more and 0.36 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, The single crystal may contain Bi, and the content of Bi is 0 parts by mass or more and 0.20 parts by mass or less in terms of metal relative to 100 parts by mass of the oxide, The electromechanical coupling coefficient k of the single crystal at 25°C ３３ A perovskite-type single crystal characterized in that the ratio of the SiO2 content to the SiO2 content is 80% or more and the coercive field is 2.5 kV / cm or more.

13. 13. The perovskite-type single crystal according to claim 12, wherein the single crystal contains less than 1000 ppm of Pb.

14. The piezoelectric constant d of the single crystal is expressed by the following formula (1): ３３ 13. The perovskite single crystal according to claim 12, wherein the fluctuation range (%) of 100×Δd ３３＠０℃～７０℃ / d ３３＠０℃ (1)

15. The dielectric constant ε of the single crystal in the range of 0°C to 70°C ３３ 13. The perovskite single crystal according to claim 12, wherein the maximum value of is 6500 or less.

16. The dielectric constant ε of the single crystal in the range of 0°C to 60°C ３３ 13. The perovskite single crystal according to claim 12, wherein the maximum value of

17. A piezoelectric element having a plurality of electrodes and a single crystal, wherein the single crystal is the single crystal according to any one of claims 12 to 16.

18. 18. An ultrasonic motor comprising at least a vibrating body on which the piezoelectric element according to claim 17 is disposed, and a moving body in contact with the vibrating body.

19. An optical device comprising the ultrasonic motor according to claim 18 in a drive section.

20. A vibrating device comprising a vibrating body having the piezoelectric element according to claim 17 arranged on a diaphragm.

21. A dust removing device, comprising a vibration unit including the vibration device according to claim 20.

22. 22. An imaging device comprising at least the dust removal device according to claim 21 and an imaging element unit, wherein a diaphragm of the dust removal device is provided on the light receiving surface side of the imaging element unit.

23. An ultrasonic probe comprising the piezoelectric element according to claim 17, wherein the piezoelectric element transmits and receives ultrasonic waves.

24. An ultrasonic diagnostic apparatus comprising at least the ultrasonic probe according to claim 23 and an image output unit.

25. 24. An ultrasonic diagnostic system comprising: the ultrasonic probe according to claim 23; a transmitter that transmits a signal output from the ultrasonic probe; and a receiver that receives the signal transmitted from the transmitter.

26. An electronic device comprising a piezoelectric acoustic component having the piezoelectric element according to claim 17.

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