JP2009046376A - Ceramic sheet, method for producing the same, and method for producing crystallographically-oriented ceramic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic sheet having a higher degree of orientation of crystals. <P>SOLUTION: The ceramic sheet is self-supported and planar and has a thickness of 10 μm or less, wherein a surface of the sheet includes a specific crystal plane; the number of crystal grains having an aspect ratio of 3 or more present in the thickness direction of the sheet is one; and the degree of orientation of the sheet measured by the Lotgering method is 30% or more. The crystal grains are composed of an oxide which has a perovskite structure and grows into crystal grains with an isotropic shape and represented by the general formula, ABO<SB>3</SB>, wherein the site A contains at least one element selected from the group consisting of Li, Na, K, Bi, and Ag; and the site B contains at least one element selected from the group consisting of Nb, Ta, and Ti. The sheet contains an oxide which grows into crystal grains with an isotropic and polyhedral shape during firing. However, since grain growth in the thickness direction of the sheet is limited and grain growth in the surface direction of the sheet is promoted, it is possible to obtain crystal grains having a high aspect ratio and a high degree of orientation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic sheet, a method for producing the same, and a method for producing a crystallographically oriented ceramic, and more particularly to a piezoelectric / electrostrictive ceramic sheet.

Conventionally, piezoelectric ceramics have been proposed that improve their characteristics by aligning the direction of the plate-like particles. For example, the crystal grains observed in the cross section in the thickness direction have a long particle diameter in the width direction (Patent Documents 1 and 2). In addition, there has been proposed one in which the piezoelectric characteristics are further improved by increasing the degree of orientation of a specific crystal plane included in the crystal. For example, a plate-like host material on which a specific crystal plane has grown is proposed by adding a guest material and an additive so that the host material is oriented and heat-sintered (Patent Documents 3 and 4). ).
JP 2006-185940 A JP 2006-185950 A Japanese Patent Laid-Open No. 11-60333 JP 2003-12373 A

  However, in the piezoelectric ceramics described in Patent Documents 1 and 2, the point that the target piezoelectric material is flat is described, but the point of increasing the degree of orientation has not been considered. In Patent Document 3, a plate-like material with a specific crystal plane developed is a composition having a layered perovskite structure, and other compositions are not taken into consideration, so that a desirable composition may not be realized. In Patent Document 4, after obtaining a plate-like crystal in a composition having a layered perovskite structure, a part of this composition is substituted to synthesize a host material composed of a desired element. In some cases, undesirable elements may remain in the finally obtained piezoelectric material. Moreover, the process was complicated.

  Other techniques for increasing the degree of crystal orientation include the production of a thin film on a substrate by sputtering, CVD, sol-gel, etc., epitaxy utilizing lattice matching with the substrate surface, and the crystal orientation of the substrate. Regardless of this, self-texture that orients a specific crystal plane by surface energy difference or atomic supply difference is known. However, in these methods, since the piezoelectric material to be obtained is in close contact with the substrate, it is extremely difficult to peel the piezoelectric material from the substrate. Thus, in the conventional method, it was not possible to easily obtain a piezoelectric ceramic having a flat plate shape, crystal plane orientation, and a uniform composition.

  This invention is made | formed in view of such a subject, and makes it one of the objectives to provide the ceramic sheet with the higher degree of crystal orientation, its manufacturing method, and the manufacturing method of crystal orientation ceramics. Another object of the present invention is to provide a ceramic sheet having a more uniform composition, a method for producing the same, and a method for producing crystal-oriented ceramics. Another object of the present invention is to provide a ceramic sheet capable of increasing the degree of orientation of crystals by a simpler process, a method for producing the same, and a method for producing crystal oriented ceramics.

  In order to achieve at least a part of the object described above, the present inventors formed inorganic particles into a self-supporting flat plate-shaped molded body having a sheet thickness of 10 μm or less, and this molded body is substantially the same as the molded body. When it was made to adjoin the inactive layer which does not react to, or it baked with the said molded object, it discovered that the orientation degree of the crystal | crystallization contained in a sheet | seat could be raised more, and came to complete this invention.

That is, the ceramic sheet of the present invention is
A self-supporting plate-shaped ceramic sheet,
The sheet thickness is 10 μm or less,
The sheet surface has substantially one crystal particle including a specific crystal plane in the sheet thickness direction.

Alternatively, the ceramic sheet of the present invention is
A self-supporting plate-shaped ceramic sheet,
The sheet thickness is 10 μm or less,
Having one crystal grain in the sheet thickness direction including a specific crystal plane on the sheet surface and having an aspect ratio of 3 or more,
The orientation degree of the sheet may be 30% or more by the Lotgering method.

Moreover, the method for producing the ceramic sheet of the present invention comprises:
A method of manufacturing a self-supporting flat ceramic sheet,
A molding step of molding the inorganic particles into a self-supporting flat molded body having a sheet thickness of 10 μm or less;
A firing step in which the molded body is adjacent to an inert layer that does not substantially react with the molded body, or is fired as the molded body;
Is included.

Moreover, the method for producing the crystallographically-oriented ceramic of the present invention is as follows.
A mixing step of mixing the powder containing the crystal particles obtained by crushing the ceramic sheet described above and the raw material powder;
A second forming step of orienting a powder containing the crystal particles among the mixed powders in a predetermined direction to form a predetermined secondary compact;
A second firing step of firing the secondary molded body so as to orient the raw material powder in a direction in which the powder containing crystal particles is oriented;
Is included.

Alternatively, the method for producing a crystallographically-oriented ceramic of the present invention is as follows:
A laminating step of laminating the above-described ceramic sheet and the raw material powder sheet containing the raw material powder to produce a secondary compact;
A second firing step of firing the laminated secondary compact so as to orient the raw material powder in a direction in which the crystal particles contained in the ceramic sheet are oriented;
May be included.

  According to the ceramic sheet of the present invention, its manufacturing method, and crystal-oriented ceramic manufacturing method, it is simpler to form inorganic particles into a self-supporting flat plate-shaped body having a sheet thickness of 10 μm or less and to fire this. The degree of crystal orientation can be increased by simple treatment. Moreover, since it is not necessary to add an additive or the like or go through a composition containing an undesired element, a ceramic sheet having a more uniform composition can be obtained. Note that “no need to add an additive or the like” does not exclude the addition of an additive to the present invention to further increase the degree of orientation.

  The ceramic sheet of the present invention is formed to have a sheet thickness of 10 μm or less, includes a specific crystal plane in the direction of the sheet surface that is the surface with the larger area, and includes substantially one crystal particle in the sheet thickness direction. It is what you have. The ceramic sheet has a sheet thickness of 10 μm or less, more preferably a sheet thickness of 5 μm or less, and even more preferably 2 μm or less. The sheet thickness is preferably 0.1 μm or more. If the sheet thickness is 0.1 μm or more, it is easy to produce a self-supporting flat sheet, and if it is 5 μm or less, the degree of orientation can be further increased. Here, the “self-supporting sheet” refers to a sheet obtained by firing a sheet-like molded body having a sheet thickness of 10 μm or less, and is laminated and fired on another sheet. It does not include a film that is in a state of being supported on a substrate by being sputtered, sol-gel, aerosol deposition method, printing method, etc. is there. The “self-supporting sheet” includes a sheet that is attached to a certain substrate or formed into a film and peeled off from the substrate before or after firing.

In the ceramic sheet of the present invention, it is preferable that the crystal grains contained in the ceramic grains have a length of crystal grains in the sheet surface direction that is greater than or equal to the length in the thickness direction of the crystal grains. This makes it easy to orient the crystal grains. The aspect ratio of the crystal grains is preferably 2 or more, more preferably 3 or more, and further preferably 4 or more. When the aspect ratio is 2 or more, the crystal grains are easily oriented. This aspect ratio is preferably 100 or less. This aspect ratio is obtained as follows. First, an SEM photograph is taken using a scanning electron microscope, and the thickness of the ceramic sheet is obtained from the SEM photograph. Next, the sheet surface of the ceramic sheet is observed, and the area S per particle is calculated from {(area of the visual field) / (number of particles)} in a visual field including about 20 to 40 crystal particles. Further, assuming that the particle form is a circle, the particle diameter was calculated by the following equation (1), and the value obtained by dividing the particle diameter by the thickness of the sheet was defined as the aspect ratio.

In the ceramic sheet of the present invention, the degree of orientation of a specific crystal plane is preferably 25% or more, and more preferably 30% or more, according to the Lotgering method. When the degree of orientation is 30% or more, for example, it can be said that the degree of orientation is sufficient to obtain crystal-oriented ceramics by crushing the ceramic sheet and further performing secondary orientation. This is because it is possible to further increase the degree of crystal orientation even in the secondary orientation. This degree of orientation is more preferably 60% or more. In this way, higher characteristics can be obtained. This specific crystal plane may be a pseudo cubic (100) plane in the sheet plane of the ceramic sheet. This pseudo-cubic (100) is an isotropic perovskite type oxide, which has a slightly distorted structure such as tetragonal, orthorhombic and trigonal crystals, but the distortion is slight. It means to display with Miller index. Here, the degree of orientation by the Lotgering method was determined by measuring the XRD diffraction pattern of the target ceramic sheet and using the following equation (2). In this equation (2), ΣI (HKL) is the sum of X-ray diffraction intensities of all crystal planes (hkl) measured on the ceramic sheet, and ΣI0 (hkl) is the same composition as the ceramic sheet and is not oriented. Is the sum of the X-ray diffraction intensities of all the crystal planes (hkl) measured for the object, and Σ′I (HKL) is a specific crystallographically equivalent crystal plane (for example (100)) measured on the ceramic sheet Surface)), and the sum of the X-ray diffraction intensities of a specific crystal plane measured for a non-oriented sheet having the same composition as that of the ceramic sheet. Here, the XRD diffraction pattern is measured. When waviness is generated in the ceramic sheet, measurement is performed in a state where the surface of the ceramic sheet is exposed using the smallest waviness. In addition, when the surface is difficult to be surfaced such as a ceramic sheet in a roll shape, the crushed material is obtained by crushing it to an extent that the aspect ratio is not less than 3, and 1 to 10 weights in a solvent such as alcohol. % Of the crushed material is dispersed using, for example, ultrasonic waves for 30 minutes, and this dispersion is spin-coated under a condition of 1000 to 4000 rpm and coated on a substrate such as glass so that they do not overlap as much as possible. Further, the crystal plane contained in the pulverized product is dispersed in a thin layer so as to be parallel to the substrate surface, and the XRD diffraction pattern is measured in this state.

  The ceramic sheet of the present invention has substantially one crystal particle in the sheet thickness direction. This is because the ceramic sheet has a thickness of 10 μm or less, and thus the grains have grown throughout the sheet thickness direction. Since this ceramic sheet has a limited number of materials present in the sheet thickness direction, when grains are grown by firing or the like, the ceramic sheet has substantially one crystal grain in the sheet thickness direction. Further, since grain growth is promoted in the direction of the sheet surface rather than in the sheet thickness direction, flat crystal particles are arranged in the direction of the sheet surface, and a specific crystal surface is oriented. Here, “substantially one crystal grain in the thickness direction” means that even if there is a portion where the crystal particles overlap in part, the crystal grain does not overlap in most of the other parts. It means to contain only one crystal grain. Further, most of the ceramic sheet such as the central portion is in a state in which two or more crystal particles are overlapped, and only one end portion is not included in the thickness direction. In this ceramic sheet, there are cases in which the grain growth of crystal grains does not reach the thickness of the ceramic sheet during grain growth, and there are cases in which the direction of the crystal plane is different. Although the thing in which the direction where the crystal plane is facing differs locally exists, it generally contains only one crystal grain in the thickness direction. In this ceramic sheet, the portion containing only one crystal particle is preferably 70% or more, more preferably 80% or more, and most preferably 90% or more in terms of the area ratio of the ceramic sheet. In this ceramic sheet, the portion where the crystal particles overlap is a part of the whole (for example, 30% or less by area ratio) and can be crushed relatively easily at the grain boundary where the crystal particles are bonded.

In the ceramic sheet of the present invention, the crystal particles are mainly composed of an oxide represented by the general formula ABO ₃ , and the A site contains one or more selected from Li, Na, K, Bi and Ag, and the B site. There may be as a particle containing at least one selected from Nb, Ta and Ti, the out _{(Li X Na Y K Z)} Nb M Ta N O 3 and _{(Bi X Na Y K Z Ag} N) TiO _{3 and the} like (X, Y, Z, M, and N represent arbitrary numbers) are particularly preferable. If it carries out like this, it will be easy to be obtained as a crystal grain in the thickness of 10 micrometers or less. Note that elements other than those listed here may be included. At this time, it is preferable that A / B of the crystal particles is 1.0 or more and 1.1 or less before firing (referred to before the firing step described later). When the A / B of the oxide represented by the general formula ABO ₃ is 1.0 or more and 1.1 or less, the aspect ratio and the degree of orientation can be increased. Here, although an example of an oxide represented by the chemical formula ABO ₃ was shown, the present invention is not limited to this example, but includes, for example, Al ₂ O ₃ , ZrO ₂ , TiO ₂ , MgO, CaO, Y ₂ O ₃ , SnO. ₂ , oxides such as ZnO and SiO ₂ and composite oxides such as PZT, BaTiO ₃ , BiFeO ₃ and YBa ₂ Cu ₃ O ₇ , nitrides such as AlN, Si ₃ N ₄ and BN, CaB ₆ , MgB ₂ , Borides such as LaB ₆ , carbides such as TiC, SiC, and WC, and tellurium compounds such as Bi ₂ Te ₃ , Bi ₂ Sb ₈ Te ₁₅ , and PbTe, CrSi ₂ , MnSi _1.73 , FeSi ₂ , CoSi ₂ Other materials such as silicide-based materials, metals, alloys, and intermetallic compounds may be used. Alternatively, the crystal particle contains an oxide represented by the general formula ABO ₃ as a main component, the A site contains Pb, and the B site contains one or more selected from Mg, Zn, Nb, Ni, Ti, and Zr. It may be a particle.

  In the ceramic sheet of the present invention, the crystal particles may be composed of inorganic particles that grow into isotropic and polyhedral crystal particles, or may be composed of inorganic particles that grow into anisotropic crystal particles. However, among these, it is preferable to be composed of inorganic particles that grow into isotropic and polyhedral crystal particles. Growing into isotropic and polyhedral crystal grains is considered to be possible to grow a specific crystal plane depending on the situation. Here, even if inorganic particles that grow into isotropic and polyhedral crystal grains are included, grain growth in the sheet thickness direction is limited, and grain growth is further promoted in the sheet surface direction. When the specific crystal plane grows in the sheet plane, the aspect ratio is large and the degree of orientation is high. Of the polyhedral shapes, the hexahedral shape is most preferable. In the case of a hexahedron, particles having a surface parallel to the sheet surface are grown isotropically in the sheet because the other four surfaces except for the two surfaces are included as growth surfaces in all directions in the molded body. The remaining two surfaces existing on the surface of the sheet are expanded without difficulty, so that particles having a large aspect ratio can be easily obtained, which is preferable. The crystal particles are preferably composed of an oxide having a perovskite structure. Some oxides having a perovskite structure grow in the form of pseudocubic dice, and the (100) plane grows in the sheet plane, so that the crystal plane (100) is easily oriented in the direction perpendicular to the sheet plane. ,preferable. On the other hand, even when the crystal particles are composed of inorganic particles that grow into anisotropic crystal particles, grain growth in the sheet thickness direction is limited, and grain growth in the sheet surface direction, The aspect ratio is large and the degree of orientation is high.

  The method for producing a ceramic sheet of the present invention includes (1) a step of preparing inorganic particles as a raw material of the ceramic sheet, (2) a step of forming inorganic particles into a sheet, and (3) a step of firing the formed sheet. It demonstrates in order of each process.

(1) Preparation Step of Inorganic Particles As inorganic particles used for the ceramic sheet, those that grow into anisotropic shaped crystal particles under a predetermined firing condition, that is, the growth forms under the predetermined firing condition grow into anisotropic shaped crystal particles. And those that grow into isotropic and polyhedral crystal grains under predetermined firing conditions, that is, those that are isotropic and polyhedral crystal grains grown under predetermined firing conditions can be used. In this regard, in the present invention, since a sheet-like molded body having a thickness of 10 μm or less is fired to cause grain growth, grain growth in the thickness direction of the molded body is limited, and more grains are formed in the sheet surface direction. Since the growth is promoted, a ceramic sheet can be produced by using an isotropic and polyhedral crystal particle grown under a predetermined firing condition, for example, a cube. Here, the “growth form in a predetermined firing condition” is defined as a morphology that is observed when crystals of inorganic particles reach an equilibrium under a given heat treatment condition. For example, the bulk is fired to promote crystallization. In this case, it is obtained by observing the shape of the surface particles. Further, the “anisotropic shape” means, for example, a plate shape, a strip shape, a column shape, a needle shape, a scale shape, or the like having a large ratio (aspect ratio) between the major axis length and the minor axis length (for example, an aspect ratio of 2 or more) ). Further, “isotropic and polyhedral shape” refers to a cubic shape, for example. Here, in general, the morphology of crystal grains produced by grain growth is almost spherical when the grain growth temperature is sufficiently low, such as 400 ° C. or less, with respect to the melting point or decomposition temperature of the solid. Originally, although the atomic arrangement is anisotropic and there is a difference in the growth rate depending on the crystal plane, the spherical grains grow because the solid atoms are very difficult to move. On the other hand, when the melting point or decomposition temperature of the solid is close to the temperature at which the grain grows, for example, when the temperature difference between them is within 200 ° C., the movement of the atoms on the grain surface during grain growth becomes active, resulting in the crystal structure. Surface morphology appears. That is, in the grain growth, a difference in the growth rate due to the crystal plane comes out, and the slow growth crystal plane develops, but the fast growth crystal plane becomes smaller or disappears. The morphology determined by the difference in the plane growth rate is called a growth type. As described above, the growth shape is anisotropic or multi-faceted, and as described above, in addition to materials with a solid melting point or decomposition temperature close to the temperature at which grains grow, low melting point compounds such as glass are fluxed. A system is preferably selected which is added to cause grain growth via a flux. This is because the movement of solid constituent elements on the particle surface becomes active through the flux. In addition, among inorganic particles that grow in a polyhedral shape, inorganic particles that grow in a hexahedral shape can be used. If it is a hexahedron, when it is made into a flat plate shape, the particles having a surface parallel to the flat plate-like sheet surface are included in all orientations in the molded body as growth surfaces other than the two surfaces. Therefore, when the grains grow isotropically in the molded body, the two sheet surfaces expand without difficulty, which is preferable because it is easy to obtain particles having a large aspect ratio. For the same reason, a column shape such as a hexagonal column or an octagonal column can be used. An additive for promoting grain growth may be added for the purpose of obtaining crystal grains having a large aspect ratio. This inorganic particle is preferably an oxide having a perovskite structure. Further, the crystal after firing is an oxide represented by the general formula ABO ₃ , and this A site is Li, Na, K, Bi and Ag. It is preferable to use one that includes one or more selected from the group B and the B site includes one or more selected from Nb, Ta, and Ti. For example, as inorganic particles, a part of the NaNbO ₃ A site is substituted with Li, K, etc., and a part of the B site is substituted with Ta ((Li _X Na _Y K _Z ) Nb _M Ta _N O ₃ : X, Y, Z, M, and N represent an arbitrary number), since the growth shape at 900 ° C. to 1300 ° C. becomes a cubic shape. Note that elements other than those listed here may be added. In the case of using (Bi _0.5 Na _0.5-x K _x ) TiO ₃ as the main composition, X> 0.01 is preferable because the growth shape becomes a cubic shape. Moreover, what contains Pb as a main component as an A site and contains 1 or more types chosen from Mg, Zn, Nb, Ni, Ti, and Zr as a B site is also preferable. Further, as a flux, glass having a melting point of 1000 ° C. or lower, such as lead borate glass, zinc borate glass, borosilicate glass, lead-silicate glass, zinc-silicate glass, and bismuth-silicate glass, is 0.1 wt% or more. If added, the growth form at 900 ° C. to 1300 ° C. is more likely to be a cubic shape, which is preferable. In this case, from the viewpoint of the dispersibility of the glass, the glass powder is not made into a sheet as it is, but after calcination once the glass is sufficiently diffused, the calcined material is pulverized, and the pulverized powder is used to make ceramics. It is preferable to produce a sheet. When an oxide that is represented by ABO ₃ is used, it is preferable to prepare the raw material so that A / B, which is the ratio of the A site to the B site, is 1.0 or more and 1.1 or less. When A / B is in the range of 1.0 or more and 1.1 or less, the aspect ratio and the degree of orientation of the crystals contained in the fired ceramic sheet can be increased. Moreover, when A / B is in the range of 1.0 or more and 1.1 or less, it is preferable in terms of compensating for an alkali component that volatilizes during firing. In addition, when obtaining crystal particles from the obtained ceramic sheet, if A / B is in the range of 1.0 or more and 1.1 or less, the alkali present in the grain boundary part when the ceramic sheet is put in water or the like. This is preferable because the rich phase dissolves and the crystal particles may be easily separated into individual particle units. Furthermore, when the thickness of the molded sheet is extremely thin, such as 3 μm or less, or when the atmosphere inside the sheath during baking (vapor of alkali component or lead component, etc.) is thin, the alkaline component or lead from the molded sheet during firing Since composition change due to volatilization of components and the like may be large, a range where A / B is 1.1 or more and 1.3 or less is also preferable.

  In the step of preparing the inorganic particles, it is preferable to pulverize and mix the raw materials of the inorganic particles, calcine the mixed powder, and further pulverize the obtained inorganic particles. As the raw material of the inorganic particles, oxides, hydroxides, carbonates, sulfates, nitrates, and tartrates of the target component can be used, but it is preferable to mainly use oxides and carbonates. In the pulverization of the inorganic particles, the particle diameter is preferably set according to the thickness of the sheet, and the median diameter (D50) of the inorganic particles is preferably 2% or more of the sheet thickness, and is preferably 5% or more. It is more preferable. Further, it is preferable that the median diameter (D50) of the inorganic particles is 60% or less of the sheet thickness. If the median diameter is 2% or more of the sheet thickness, the pulverization process is easy, if it is 5% or more, the pulverization process is easier, and if it is 60% or less, the sheet thickness is easy to adjust. As this particle diameter, a value measured by dispersing in a dispersion medium (such as an organic solvent or water) using a laser diffraction / scattering particle size distribution measuring apparatus is used. The inorganic particles are preferably pulverized by wet pulverization. For example, a ball mill, a bead mill, a trommel, or an attritor may be used.

(2) Sheet Forming Step Inorganic particles are formed into a self-supporting flat plate-shaped body having a sheet thickness of 10 μm or less. As a method for forming the sheet, for example, a doctor blade method using a slurry containing inorganic particles, an extrusion method using a clay containing inorganic particles, or the like can be used. When using the doctor blade method, a slurry is applied to a flexible plate (for example, an organic polymer plate such as a PET film), and the applied slurry is dried and solidified to form a molded body, and the molded body and the board are peeled off. Thus, a molded body before firing the ceramic sheet may be produced. When preparing a slurry or clay before molding, inorganic particles may be dispersed in a suitable dispersion medium, and a binder, a plasticizer, or the like may be added as appropriate. Moreover, it is preferable to prepare the slurry so that the viscosity is 500 to 700 cP, and it is preferable to defoam under reduced pressure. The thickness of the sheet is 10 μm or less, more preferably 5 μm or less, and most preferably 2 μm or less. When it is 10 μm or less, a high degree of orientation can be obtained, and when it is 5 μm or less, a higher degree of orientation can be obtained. The sheet thickness is preferably 0.1 μm or more. If the sheet thickness is 0.1 μm or more, it is easy to create a self-supporting flat sheet. Other methods include film deposition on substrates such as resin, glass, ceramics and metals by high-speed spraying of particles, such as aerosol deposition methods, and vapor phase methods such as sputtering, CVD, and PVD. You may produce the molded object before baking of a ceramic sheet by peeling. In this case, since the density of the molded body before firing can be increased, there are advantages such as grain growth at a low temperature, prevention of volatilization of constituent elements, and the resulting ceramic sheet has a high density.

(3) Firing step of molded body An inactive layer (for example, a fired ceramic plate or Pt plate, a carbon plate, a graphite plate, a molybdenum plate, a non-reactive layer which does not substantially react with the molded body in the molding step) It fires in the state which adjoined the tungsten plate etc.), or it fires in the state as this molded object. For example, alumina sheets, zirconia, spinel, carbon, graphite, molybdenum, tungsten, platinum, and the like may be fired by alternately laminating green sheets on layers that are inactive at the firing temperature of the molded body. Alternatively, the molded body sheet and the inert sheet may be wound in a roll shape and fired. Or it is good also as what forms a molded object in a sheet form on an inactive layer, and makes it peel from this inactive layer after baking. Or it is good also as what forms a sheet-like molded object into an inactive layer, and removes an inactive layer after baking. For example, when using graphite for the inert layer, after firing in a non-oxidizing atmosphere (for example, in nitrogen) and obtaining a desired ceramic sheet in the presence of the inert layer, an oxidizing atmosphere (for example, lower than that temperature) The heat treatment may be performed again in the atmosphere) and the graphite may be burned to be removed. Moreover, it is preferable to bake a molded object in the volatilization suppression state which suppresses volatilization of the specific components (for example, alkali etc.) contained in a molded object. If it carries out like this, it can suppress that the composition of the ceramic sheet after baking shift | deviates by suppressing that a specific element from a molded object volatilizes. For example, the compact may be fired in a state where inorganic particles different from the compact are coexisting as a volatilization-suppressed state. If it carries out like this, it can suppress that a specific component volatilizes from a molded object comparatively easily by volatilizing a specific component from the coexisting inorganic particle. At this time, “another inorganic particle” may be in the form of a powder or a molded body. Alternatively, the compact may be fired in a sealed state in a sheath with a lid as a volatilization-suppressed state. At this time, it is preferable to make the space inside the sheath as small as possible. Here, if the atmosphere inside the sheath is too thick, for example, if the amount of other inorganic particles coexisting inside the sheath is excessively large, sintering and grain growth of the molded body are activated, resulting in sheet undulation. Or, the grain growth may reduce the surface area of the particle, that is, increase the thickness and reduce the aspect ratio. For this reason, it is important to empirically set the volume inside the sheath, the amount of the molded body, the amount of inorganic particles to coexist, etc. to an appropriate state so that the atmosphere inside the sheath is in an optimal state. In addition, when firing with inorganic particles coexisting, it is preferable to coexist inorganic particles having the same composition as the molded body, but coexist with particles that easily volatilize a specific component than the inorganic particles constituting the molded body. It is possible to replenish the ceramic sheet with a specific component. In the firing process, it is more important to provide an optimum atmosphere at an optimum timing. For example, firing is performed at the first firing temperature in a sheath controlled to the first atmosphere, and the temperature is returned to room temperature. Then, firing may be performed at a second firing temperature higher than the first firing temperature in the sheath controlled to the second atmosphere. The firing atmosphere may be in the air, but in terms of suppressing volatilization of constituent elements, reactivity with the inert layer, etc., in an oxygen atmosphere, a neutral atmosphere such as nitrogen, in the coexistence of hydrogen or hydrocarbons, etc. The reducing atmosphere may be in a vacuum. Further, from the viewpoint of promoting in-plane grain growth, weighted firing such as hot pressing may be performed.

  This firing process will be described with reference to the drawings. 1A and 1B are explanatory diagrams of the firing device 10, in which FIG. 1A is a side view and FIG. 1B is a cross-sectional view taken along line AA in FIG. The firing device 10 is used when firing the sheet molded body 20 in a firing furnace (not shown). The setter 12 is a fired ceramic plate on which the unfired sheet molded body 20 is placed, and sheet molding. An unfired co-fired unfired sheet molded body 14 formed of the same inorganic particles as the body 20 and having a thickness larger than that of the sheet molded body 20, and the sheet molded body 20 disposed on the coexisting unfired sheet molded body 14 It is comprised by the square plate 16 which is a baked ceramic board used as a lid | cover. As shown in FIG. 1, by enclosing the four sides of the sheet molded body 20 with a coexisting unfired sheet molded body 14, a specific component (for example, alkali) is volatilized from the sheet molded body 20 and the composition changes. Is prevented. Here, the setter 12 is assumed to be a flat plate, but a setter having a rough surface on the sheet mounting surface, a honeycomb setter having a plurality of through holes on the sheet mounting surface, and dimple processing. The contact area with the sheet molded body 20 such as a setter may be reduced to prevent the setter and the sheet molded body 20 from being welded. Further, alumina powder or zirconia powder that is stable at the firing temperature of the sheet molded body 20 may be placed on the mounting surface of the setter 12, and the sheet molded body 20 may be placed thereon and fired. Here, instead of coexisting the green sheet compact, in the case of coexisting in the powder inside the sheath, adjust the setting method and size of the setter inside the sheath, the method of stacking, the position of placing the powder, etc. Thus, the atmosphere inside the sheath can be adjusted uniformly, and when a plurality of sheets are fired, each sheet can have a uniform crystal particle structure.

Regarding the firing conditions, the sheet molded body 20 is fired at a firing temperature at which an equilibrium crystal is obtained by firing, for example, at a temperature higher by 10% or more than the firing temperature at which densification and grain growth occur by firing the bulk. It is preferable. At a temperature higher by 10% or more, the grain growth of the sheet molded body 20 of 10 μm or less can be sufficiently advanced. In addition, it is preferable to bake at a high temperature so as not to decompose the material of the molded body. In particular, when the thickness of the sheet becomes thinner, the grain growth becomes difficult, so it is preferable to set the firing temperature to be higher. For example, as inorganic particles, in the firing process of LiN, K, etc. added to the A site of NaNbO ₃ and Ta added to the B site ((Li _X Na _Y K _Z ) Nb _M Ta _N O ₃ ) The body firing temperature is preferably 900 ° C. or higher and 1250 ° C. or lower. When the firing temperature is 900 ° C. or higher, the growth of particle crystals is promoted, and when the firing temperature is 1250 ° C. or lower, volatilization of alkali components and the like can be suppressed to a low level and the material can be prevented from being decomposed. Thus, by firing, the inorganic particles contained in the sheet molded body 20 grow into crystal particles whose length in the sheet surface direction is not less than the length in the thickness direction and the degree of orientation is not less than 30%. is there.

  The obtained ceramic sheet may be crushed to an extent that the aspect ratio does not become 2 or less, more preferably 3 or less, to obtain powder of crystal particles, and may be used as a raw material for crystal oriented ceramics. This crystallographically-oriented ceramic can have an arbitrary shape whose thickness direction exceeds 10 μm, for example. That is, the ceramic sheet may be produced in order to obtain crystal particles used in the process for producing crystal-oriented ceramics. An example of a method for producing this crystal oriented ceramic will be described below. The crystal-oriented ceramic is subjected to a mixing step in which powder containing crystal particles obtained from a ceramic sheet, other raw material powder (for example, non-oriented inorganic particles), and a binder, a plasticizer, and the like are appropriately mixed. It is good also as what performs the secondary shaping | molding process shape | molded into the secondary molded object of a predetermined shape by performing orientation shaping | molding (secondary orientation) so that a crystal grain may face a fixed direction. Note that the powder containing the crystal particles may be one in which the crystal particles are separated or may be a combination of a certain number. Orientation molding can be performed by the above-described doctor blade method, extrusion molding method, or the like. Then, a secondary firing step of firing the secondary compact is performed so that other raw material powders are oriented in the direction in which the crystal particle powders are oriented, thereby obtaining crystal oriented ceramics. The firing temperature in the secondary firing step may be a firing temperature at which an equilibrium crystal is obtained under the above-mentioned predetermined firing conditions, or may be a temperature higher by 10% or more than this temperature. In addition, even when it is a case where it does not bake in the volatilization suppression state at the time of baking of the sheet | seat molded object 20 mentioned above, by adding the component volatilized at the mixing process or the secondary shaping | molding process, the composition ratio aiming at crystal orientation ceramics and can do. The degree of orientation of the ceramic sheet is preferably higher, but it can be increased by firing after this secondary orientation, so that it may be 30% or more.

  Alternatively, the crystallographically-oriented ceramic may be produced using a ceramic sheet without crushing. For example, the above-described ceramic sheet and the raw material powder sheet containing the raw material powder are laminated to produce a secondary compact, and the raw material powder is oriented in the direction in which the crystal particles contained in the ceramic sheet are oriented. And a second firing step in which the secondary molded body laminated so as to be oriented is fired. FIG. 8 is an explanatory view of an example of producing a crystal-oriented ceramic by laminating ceramic sheets. Specifically, a raw material paste containing raw material powder is prepared by mixing other raw material powders (for example, non-oriented inorganic particles, etc.) and a binder or a plasticizer as appropriate, and this raw material paste has a predetermined thickness. For example, the raw material powder sheet 32 having a thickness of 10 μm to 20 μm is formed by screen printing or a doctor blade method. The raw material powder sheet 32 is laminated with a ceramic sheet 30 containing crystal particles 31 grown in the plane direction (FIG. 8A), and this laminated one is dried at a drying temperature of 80 to 150 ° C. as appropriate. The process of laminating the ceramic sheets 30 and the raw powder sheets 32 alternately is repeated until the required thickness of the crystallographically oriented ceramics is reached (FIG. 8B), and the secondary compact 40 (laminate). ) Is produced (FIG. 8C). Subsequently, the secondary compact 40 is fired at a predetermined firing temperature, the raw material contained in the raw material powder sheet 32 is grown in the crystal direction of the crystal particles 31, and the crystal oriented ceramics 50 including many oriented crystals 52 is obtained. Is obtained (FIG. 8D). Prior to the firing, degreasing may be performed by calcining at a predetermined calcining temperature (for example, 600 ° C.). In the second firing step, firing the secondary compact 40 by, for example, hot pressing, which is performed while pressing, is preferable in order to further promote grain growth and densification. Even in this case, similarly to the above, other raw material powders can be oriented in the direction in which the crystal particles are oriented using the ceramic sheet, so that the crystal oriented ceramics can be easily produced. it can.

  According to the self-supporting flat plate-like ceramic sheet of the present embodiment described in detail above, the sheet thickness is 10 μm or less, and crystal grains including a specific crystal plane (pseudocubic (100)) are included in the sheet surface. Since there is one sheet in the thickness direction and the orientation degree of the sheet is 30% or more by the Lotgering method, higher characteristics can be obtained as a piezoelectric / electrostrictive body. In addition, according to the method for producing a ceramic sheet, it is possible to align without forming an additive for increasing the degree of orientation and without substituting components after firing only by forming the thickness to 10 μm or less and firing. Since highly crystalline grains can be obtained, a homogeneous composition can be obtained by a simpler treatment.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the ceramic sheet is crushed and used as a raw material for crystal-oriented ceramics, but may be used for other purposes. For example, the ceramic sheet of the present invention includes a dielectric material, a pyroelectric material, a piezoelectric material, a ferroelectric material, a magnetic material, an ion conductive material, an electron conductive material, a heat conductive material, a thermoelectric material, a superconductive material, It can be used for a polycrystalline material made of a substance whose function and characteristics such as wear-resistant material have crystal orientation dependency. Specifically, various sensors such as acceleration sensors, pyroelectric sensors, ultrasonic sensors, electric field sensors, temperature sensors, gas sensors, knocking sensors, yaw rate sensors, airbag sensors, piezoelectric gyro sensors, energy conversion elements such as piezoelectric transformers, Low-loss actuators or low-loss resonators such as piezoelectric actuators, ultrasonic motors, and resonators, capacitors, bimorph piezoelectric elements, vibration pickups, piezoelectric microphones, piezoelectric ignition elements, sonar, piezoelectric buzzers, piezoelectric speakers, oscillators, filters, dielectric elements, High performance when applied to microwave dielectric elements, thermoelectric conversion elements, pyroelectric elements, magnetoresistive elements, magnetic elements, superconducting elements, resistance elements, electron conducting elements, ion conducting elements, PTC elements, NTC elements, etc. Various elements can be obtained. At this time, the aspect ratio of the crystal grains is appropriately set to a value according to the application.

  Below, the example which manufactured the ceramic sheet concretely is demonstrated as an experiment example.

[Experimental Example 1]
(Inorganic particle synthesis process)
Each powder (Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ so as to have a composition ratio of Li _0.07 (Na _0.5 K _0.5 ) _0.93 Nb _0.9 Ta _0.1 O ₃ ) Was weighed. A weighed product, zirconia balls, and ethanol as a dispersion medium were placed in a polypot, and wet mixing and pulverization were performed for 16 hours with a ball mill. The obtained slurry was dried with an evaporator and a dryer, and then pre-fired under conditions of 850 ° C. and 5 hours. This calcined powder, zirconia balls, ethanol as a dispersion medium, wet pulverized with a ball mill for 5 hours, dried with an evaporator and a dryer, and Li _0.07 (Na _0.5 K _0.5 ) _0.93 Nb _0.9 Ta _0.1 O ₃ inorganic Particle powder was obtained. When the average particle diameter of this powder was measured using a laser diffraction / scattering particle size distribution analyzer LA-750 manufactured by HORIBA using water as a dispersion medium, the median diameter (D50) was 0.6 μm.
(Self-standing sheet forming process)
Into a mixture of equal amounts of toluene and isopropanol as a dispersion medium, the above inorganic particle powder, polyvinyl butyral (BM-2, manufactured by Sekisui Chemical) as a binder, a plasticizer (DOP, manufactured by Kurokin Kasei), and dispersion An agent (SP-O30, manufactured by Kao) was mixed to prepare a slurry-like forming raw material. The amount of each raw material used was 100 parts by weight of the dispersion medium, 10 parts by weight of the binder, 4 parts by weight of the plasticizer, and 2 parts by weight of the dispersant with respect to 100 parts by weight of the inorganic particles. Next, the obtained slurry was stirred and defoamed under reduced pressure to prepare a viscosity of 500 to 700 cP. The viscosity of the slurry was measured with an LVT viscometer manufactured by Brookfield. The obtained slurry was formed into a sheet on a PET film by a doctor blade method. The thickness after drying was 10 μm.
(Standing sheet firing process)
A sheet-like molded body peeled off from the PET film was cut into a 50 mm square with a cutter and placed on the center of a setter (dimension 70 mm square, height 5 mm) made of zirconia. In this setter, an unsintered sheet molded body (dimensions 5 mm × 40 mm, thickness 100 μm) made of the same molding raw material as the sheet-shaped molded body is placed outside the four sides of the sheet-shaped molded body, and enclosed. A zirconia square plate (size 70 mm square, height 5 mm) was further placed thereon. Thus, the space for the sheet-like molded body was made as small as possible, and the firing conditions were set such that the same molding raw material coexisted. Then, after degreasing at 600 ° C. for 2 hours, baking was performed at 1000 ° C. for 5 hours. After firing, the part not welded to the setter was taken out, and this was used as the ceramic sheet of Experimental Example 1.

[Experimental Examples 2 and 3]
Except for setting the firing temperature to 1050 ° C. and 1100 ° C. in the firing step, the same steps as in Experimental Example 1 were performed, and the obtained ceramic sheets were referred to as Experimental Examples 2 and 3, respectively.

[Experimental Examples 4 and 5]
In the molding step, the same steps as in Experimental Example 1 were performed except that the thickness of the sheet-like molded body was 5 μm and 15 μm and the firing temperature was 1100 ° C. It was set to 5.

[Experimental Examples 6 to 10]
In the synthesis step, the composition of the inorganic particles is Li _0.07 (Na _0.5 K _0.5 ) _0.93 NbO ₃ , Li _0.07 (Na _0.5 K _0.5 ) _0.97 NbO _3.02 , Li _0.07 (Na _0.5 K _0.5 ) _1.03 NbO _3.05 , Li _0.1 (Na _0.5 K _0.5 ) _1.1 NbO _3.1 , Li _0.07 (Na _0.5 K _0.5 ) _0.91 NbO _2.99 , that is, A / B = 1.00, 1.04, 1.10, 1.20, 0 in the general formula ABO ₃ Inorganic particle powder was prepared so as to be .98, and the same process as in Experimental Example 1 was performed except that the firing temperature was set to 1100 ° C., and the obtained ceramic sheets were set as Experimental Examples 6 to 10, respectively.

[Experimental Example 11]
Experimental Example 1 in which each powder (Bi ₂ O ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Ag ₂ O, TiO ₂ ) was weighed so that the composition ratio of (Bi _0.5 Na _0.35 K _0.1 Ag _0.05 ) TiO ₃ was obtained. After wet mixing, pulverization and drying in the same manner as in Example 1, the mixture was calcined at 900 ° C. for 2 hours, and the obtained calcined powder was pulverized and dried in the same manner as in Experimental Example 1 (Bi _0.5 Na _0.35 K). _0.1 Ag _0.05 ) TiO ₃ inorganic particle powder was obtained. This powder was obtained in the same manner as in Experimental Example 1 except that the thickness of the sheet was 5 μm in the molding step, the degreasing temperature was 600 ° C. for 2 hours, and the firing temperature was 1250 ° C. for 3 hours in the firing step. The obtained ceramic sheet was used as Experimental Example 11.

[Experimental example 12]
ZnO—B ₂ O ₃ —SiO ₂ glass powder to a synthetic powder having a composition ratio of 0.2 Pb (Mg _0.33 Nb _0.67 ) O ₃ −0.35 PbTiO ₃ −0.45 PbZrO ₃ with 1 wt% NiO added. 1% by weight (ASF 1891 manufactured by Asahi Glass (AGG)) was added, and this weighed product, zirconia balls and ion-exchanged water as a dispersion medium were placed in a polypot, and wet-mixed for 16 hours with a ball mill. The obtained slurry was dried with a dryer and calcined at 800 ° C. for 2 hours. This calcined powder, zirconia balls, and ion-exchanged water as a dispersion medium were added, wet-ground by a ball mill for 5 hours, and dried by a drier to obtain inorganic particle powder. This powder was molded at a sheet thickness of 1 μm in the molding process. The obtained sheet was placed on a zirconia square plate placed in an alumina sheath. Within this sheath, as a powder for adjusting the firing _{atmosphere, 0.2Pb (Mg 0.33 Nb 0.67)} O 3 -0.35PbTiO 3 coexist small amount of inorganic particles powder having a composition of -0.45PbZrO _3, firing The process was the same as in Experimental Example 1 except that the degreasing conditions were 600 ° C., 2 h and 1100 ° C., 5 h, and the obtained ceramic sheet was used as Experimental Example 12.

[Experimental Example 13]
An inorganic particle powder having a composition of 0.2Pb (Mg _0.33 Nb _0.67 ) O ₃ −0.35PbTiO ₃ −0.45PbZrO ₃ was used, NiO and glass powder were not added, and the sheet thickness was formed to 2 μm. Except for this, the same steps as in Experimental Example 12 were performed, and the obtained ceramic sheet was determined as Experimental Example 13.

[Experimental Example 14]
Except that the A / B of Experimental Example 12 0.2Pb (Mg _0.33 Nb _0.67 ) O ₃ −0.35PbTiO ₃ −0.45PbZrO ₃ was 1.1, the same steps as in Experimental Example 12 were performed, The obtained ceramic sheet was used as Experimental Example 14.

[Electron micrograph]
About the said Experimental Examples 1-14, the SEM photograph was image | photographed using the scanning electron microscope (JEOL JSM-6390). The thickness of the ceramic sheet was determined from the SEM photograph as a result of the photographing. Further, by observing the sheet surface of the ceramic sheet, the area S per particle is calculated from {(area of the visual field) / (number of particles)} in a visual field including about 20 to 40 crystal particles. Assuming that the particle form is a circle, the particle diameter was calculated by the above formula (1), and the value obtained by dividing the particle diameter by the thickness was defined as the aspect ratio.

[Orientation]
About the said Experimental Examples 1-14, the XRD diffraction pattern when X-rays were irradiated with respect to a sheet | seat surface was measured using the XRD diffraction apparatus (RAD-IB made from Rigaku), and pseudo cubic (100) was measured by the Lotgering method. The degree of orientation of the plane was calculated using the above formula (2) using the pseudo cubic (100), (110), and (111) peaks.

  The evaluation results of Experimental Examples 1 to 14 thus obtained are shown in Table 1 and FIGS. Table 1 shows the sample name, inorganic particles, average particle size according to median diameter (D50), firing temperature, sheet thickness, aspect ratio, and degree of orientation. FIG. 2 is an X-ray diffraction pattern of Experimental Example 4, FIG. 3 is an SEM photograph of Experimental Example 4, and FIG. 4 is a graph showing the aspect ratio of the crystals contained in the ceramic sheet and the degree of orientation by the Lotgering method. FIG. 5 is a diagram illustrating the relationship between the degree of orientation, the aspect ratio, and the A / B value. In FIG. 4, Experimental Examples 1 to 5 in which the firing temperature or thickness is changed are triangular, Experimental Examples 6 to 10 in which the composition ratio is changed are round, Experimental Example 11 is square, and Experimental Examples 12 to 12 14 is indicated by a rhombus. 4 and 5, the numbers of the experimental examples are assigned to each, and the preferred range (orientation degree of 25% or more) of the ceramic sheet is indicated by a shaded region, and the more preferred range (the aspect ratio is 3 or more, the orientation degree). Is indicated by a dotted line. 6 is an X-ray diffraction pattern of Experimental Example 12, and FIG. 7 is an SEM photograph of Experimental Example 12. According to the result of this example, as shown in FIGS. 3 and 7, the ceramic sheet of the present invention grows crystals in the surface direction of the sheet and includes one particle in the thickness direction of the sheet. Grown into grains. In these ceramic sheets, the portion containing only one crystal particle was 90% or more in terms of the area ratio of the ceramic sheet. As shown in FIG. 3 and FIG. 7, the ceramic sheet has almost no agglomeration such that crystals overlap each other, and can be crushed relatively easily at the grain boundary where the crystal particles are in contact with each other. In addition, as shown in FIGS. 4 and 5, in the soda potassium niobate, according to Experimental Examples 1 to 3, it was found that a preferable range was obtained when the firing temperature was 1100 ° C. or higher. Moreover, according to Experimental Examples 1-14, it turned out that it will become a more suitable range if sheet | seat thickness shall be 10 micrometers or less. In addition, according to Experimental Examples 6 to 10, 12, and 14, it was found that when A / B is in a range of 1.0 to 1.2, a more preferable range is obtained.

[Production of crystal-oriented ceramics]
Inorganic particles after calcination of Experimental Example 4 so that the composition of the crystal-oriented ceramic after firing is equal to Li _0.03 Na _0.475 K _0.475 Nb _0.82 Ta _0.18 O ₃ in a mixture of equal amounts of toluene and isopropanol as a dispersion medium Powder, a crushed material (powder containing crystal particles) obtained by pulverizing the ceramic sheet of Experimental Example 4 to have an aspect ratio of 3 or more, and polyvinyl butyral (BM-2, manufactured by Sekisui Chemical Co., Ltd.) as a binder, A plasticizer (DOP, manufactured by Kurokin Kasei) and a dispersant (SP-O30, manufactured by Kao) were mixed to prepare a slurry-like molding raw material. The amount of each raw material used was 30 parts by weight of the pulverized product containing crystal particles, 100 parts by weight of the dispersion medium, 10 parts by weight of the binder, 4 parts by weight of the plasticizer, and 2 parts by weight of the dispersant with respect to 100 parts by weight of the inorganic particles. . Next, the obtained slurry was stirred and defoamed under reduced pressure to prepare a viscosity of 2500 to 3000 cP. The viscosity of the slurry was measured with an LVT viscometer manufactured by Brookfield. The obtained slurry was formed into a flat plate shape by a doctor blade method so that crystal grains were oriented in one direction and the thickness after drying was 100 μm. This flat plate was dried at room temperature, degreased at 600 ° C. for 2 hours, and then fired at 1100 ° C. for 5 hours to grow the inorganic particle powder, thereby obtaining crystal oriented ceramics.

Moreover, the crystal-oriented ceramic was produced without crushing the ceramic sheet. First, the terpineol as the dispersion medium is mixed with the inorganic particle powder after the calcination of Experimental Example 6 so that the composition of the crystal-oriented ceramic after firing is Li _0.03 Na _0.475 K _0.475 Nb _0.82 Ta _0.18 O ₃ , and the binder Polyvinyl butyral (BM-2, manufactured by Sekisui Chemical Co., Ltd.) and a plasticizer (DOP, manufactured by Kurokin Kasei) were mixed to prepare a paste-like molding raw material. The amount of each raw material used was 25 parts by weight of the dispersion medium, 3 parts by weight of the binder, and 1 part by weight of the plasticizer with respect to 100 parts by weight of the inorganic particles. The obtained paste was formed into a raw material powder sheet having a thickness of 15 μm by a screen printing method, and after placing the ceramic sheet of Experimental Example 4 on this forming raw material powder sheet in a stage before drying, It was dried for 3 minutes with a dryer at 150 ° C. This process was repeated 100 times to produce a secondary molded body (laminate) having a thickness of about 2 mm. This was calcined at 600 ° C. for 3 hours, degreased, and then subjected to atmospheric hot pressing under the conditions of a firing temperature of 1050 ° C., a pressure of 30 MPa, and a keep time of 3 hours, to obtain a crystallographically oriented ceramic. FIG. 9 is an SEM photograph of the crystallographically-oriented ceramic produced from the laminate. The crystal-oriented ceramic produced in this way had a density of 98% and an orientation degree of 90%. Thus, it was possible to produce a crystallographically-oriented ceramic with a high degree of orientation by a very simple method of using a ceramic sheet produced with a thickness of 10 μm or less.

  INDUSTRIAL APPLICABILITY The present invention can be used in the field of manufacturing ceramics with oriented crystals, for example, piezoelectric / electrostrictive bodies.

It is explanatory drawing of the baking apparatus 10, FIG. 1 (a) is a side view, FIG.1 (b) is AA sectional drawing of (a). 7 is an X-ray diffraction pattern of Experimental Example 4. It is a SEM photograph of Experimental example 4, Fig.3 (a) is a sheet | seat surface, FIG.3 (b) is a torn surface. It is a figure showing the relationship between the aspect-ratio of the crystal | crystallization contained in a ceramic sheet, and the orientation degree by a Lotgering method. It is a figure showing the relationship between orientation degree and an aspect-ratio, and A / B value. 10 is an X-ray diffraction pattern of Experimental Example 11. 14 is a SEM photograph of Experimental Example 11. It is explanatory drawing which produces a crystal orientation ceramics by laminating | stacking a ceramic sheet. It is a SEM photograph of crystal orientation ceramics produced with a layered product.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sintering machine, 12 setters, 14 Unsintered sheet molded object for coexistence, 16 square plate, 20 sheet molded object, 30 ceramic sheet, 31 crystal particle, 32 raw material powder sheet, 40 secondary molded object, 50 crystal oriented ceramics, 52 Oriented crystal.

Claims (24)

A self-supporting plate-shaped ceramic sheet,
The sheet thickness is 10 μm or less,
Having substantially one crystal grain including a specific crystal face on the sheet surface in the sheet thickness direction;
Ceramic sheet.   2. The ceramic sheet according to claim 1, wherein a length of the crystal particles in the sheet surface direction is equal to or longer than a length in the thickness direction of the crystal particles.   The ceramic sheet according to claim 1 or 2, wherein the degree of orientation of the sheet is 30% or more by the Lotgering method.   The ceramic sheet according to any one of claims 1 to 3, wherein the sheet thickness is 0.1 μm or more and 5 μm or less. The crystal grains are mainly composed of an oxide represented by the general formula ABO ₃ , the A site includes one or more selected from Li, Na, K, Bi and Ag, and the B site is composed of Nb, Ta and Ti. The ceramic sheet according to any one of claims 1 to 4, which is a particle containing one or more selected. The crystal grains are mainly composed of an oxide represented by the general formula ABO ₃ , the A site contains Pb, and the B site contains one or more selected from Mg, Zn, Nb, Ni, Ti and Zr. The ceramic sheet according to any one of claims 1 to 4, wherein   The ceramic sheet according to claim 5 or 6, wherein the crystal particles have an A / B before firing of 1.0 or more and 1.3 or less.   The ceramic sheet according to claim 1, wherein the crystal particles are composed of inorganic particles that grow into isotropic and polyhedral crystal particles.   The ceramic sheet according to any one of claims 1 to 7, wherein the crystal particles are composed of inorganic particles that grow into anisotropic crystal particles.   The ceramic sheet according to any one of claims 1 to 9, wherein the crystal particles are made of an oxide having a perovskite structure. A method of manufacturing a self-supporting flat ceramic sheet,
A molding step of molding the inorganic particles into a self-supporting flat molded body having a sheet thickness of 10 μm or less;
A firing step in which the molded body is adjacent to an inert layer that does not substantially react with the molded body, or is fired as the molded body;
The manufacturing method of the ceramic sheet containing this.   The method for producing a ceramic sheet according to claim 11, wherein the forming step uses inorganic particles that grow into isotropic and polyhedral crystal particles under predetermined firing conditions.   The method for producing a ceramic sheet according to claim 11, wherein the forming step uses inorganic particles that grow into anisotropic crystal particles under predetermined firing conditions.   The method for producing a ceramic sheet according to claim 11, wherein inorganic particles having a perovskite structure are used in the forming step. In the molding step, the oxide represented by the general formula ABO ₃ is a main component, the A site includes one or more selected from Li, Na, K, Bi and Ag, and the B site is composed of Nb, Ta and Ti. The manufacturing method of the ceramic sheet of any one of Claims 11-14 using the inorganic particle used as the oxide containing 1 or more types chosen. In the molding step, the oxide A site represented by the general formula ABO ₃ contains one or more selected from Li, Na and K, and the B site contains one or more selected from Nb and Ta; Using inorganic particles
The method for producing a ceramic sheet according to claim 15, wherein in the firing step, a firing temperature of the formed body is set to 900 ° C. or more and 1250 ° C. or less. In the molding step, an oxide containing the oxide represented by the general formula ABO ₃ as a main component, the A site containing Pb, and the B site containing one or more selected from Mg, Zn, Nb, Ni, Ti and Zr. The manufacturing method of the ceramic sheet of any one of Claims 11-14 using the inorganic particle used as a thing.   The method for producing a ceramic sheet according to any one of claims 15 to 17, wherein in the forming step, inorganic particles of an oxide having an A / B of 1.0 or more and 1.3 or less are used.   The ceramic sheet according to any one of claims 11 to 18, wherein in the forming step, the formed body is formed using the inorganic particles having a median diameter of 2% to 60% of the sheet thickness. Production method.   The method for producing a ceramic sheet according to any one of claims 11 to 19, wherein, in the firing step, the compact is fired in a volatilization-suppressed state that suppresses volatilization of a specific component contained in the compact.   21. The method for producing a ceramic sheet according to claim 20, wherein in the firing step, the compact is fired in a state where the inorganic particles different from the compact are coexisting as the volatilization-suppressed state. A mixing step of mixing the powder containing the crystal particles obtained by crushing the ceramic sheet according to any one of claims 1 to 10 and a raw material powder,
A second forming step of orienting a powder containing the crystal particles among the mixed powders in a predetermined direction to form a predetermined secondary compact;
A second firing step of firing the secondary molded body so as to orient the raw material powder in a direction in which the powder containing crystal particles is oriented;
The manufacturing method of the crystal orientation ceramics containing this. A laminating step of laminating the ceramic sheet according to any one of claims 1 to 10 and a raw material powder sheet containing a raw material powder to produce a secondary compact,
A second firing step of firing the laminated secondary compact so as to orient the raw material powder in a direction in which the crystal particles contained in the ceramic sheet are oriented;
The manufacturing method of the crystal orientation ceramics containing this.   24. The method for producing a crystallographically-oriented ceramic according to claim 23, wherein in the second firing step, the raw material powder is oriented in a direction in which the crystal particles are oriented by firing the secondary compact while applying pressure. .