Perovskite ceramic shaped body and method for producing the same

Abstract

A method for producing a dense perovskite ceramic shaped body containing an alkaline earth metal element, at least one element selected from Ti, Zr and Hf, and oxygen, and having a relative density of 60% or more, the method comprising a contact reaction step in which a precursor shaped body containing a gel containing at least one oxide selected from Ti, Zr and Hf and water alone, and a liquid containing a hydroxide of an alkaline earth metal element are brought into contact. The obtained shaped body is a collection of crystal domains (2) of a perovskite ceramic crystal (1), the crystal domains (2) being connected to each other.

Description

Technical Field

[0001] This invention relates to: dense perovskite-type ceramic molded bodies, methods for manufacturing the same, and precursor materials for manufacturing perovskite-type ceramic molded bodies used in the manufacturing of the same. Background Technology

[0002] Perovskite-type composite oxides such as barium titanate, barium zirconate, strontium zirconate, and calcium barium zirconate titanate are known as suitable piezoelectric and dielectric materials for electrical equipment and electronic products. It is said that components used in these products are preferably formed from high-density sintered bodies to fully utilize their performance. Furthermore, such sintered bodies (sintered molded bodies) can conventionally be manufactured by mixing powder or particles of the composite oxide with a desired binder, then forming a molded body of a predetermined shape, and subsequently heat-treating it at a high temperature, for example, 1700°C (in the case of barium zirconate).

[0003] Creating such high-temperature manufacturing conditions requires a large amount of thermal energy, which is not economically desirable. Therefore, for example, a method is sought to manufacture sintered bodies formed from perovskite-type composite oxides at temperatures below 200°C.

[0004] For example, Non-Patent Document 1 discloses a method for manufacturing a barium zirconate sintered molded body, the method being as follows: coating the surface of barium zirconate particles with zirconium oxide gel, then pressing the obtained composite particles to form a molded body of a specified shape, and then immersing the molded body in a saturated aqueous solution of barium hydroxide at 75°C.

[0005] Existing technical documents

[0006] Non-patent literature

[0007] Non-patent literature 1: Yuki Yamaguchi, J.Ceram.Soc.Jpn., 128

[10] (2020)747-755 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] The object of this invention is to provide a method for manufacturing a dense perovskite-type ceramic molded body having a relative density of 60% or more. Another object of this invention is to provide a raw material for a precursor molded body suitable for manufacturing such a molded body. Furthermore, another object of this invention is to provide a perovskite-type ceramic molded body that, by being dense, is suitable for use as an electrolyte in a solid oxide fuel cell, etc.

[0010] It should be noted that, in this invention, the relative density of perovskite ceramics is the measured density relative to the theoretical density obtained from X-ray diffraction and Rietveld analysis (in the case of barium zirconate, it is 6.117 g / cm³). 3 The ratio of the measured density to the apparent density of the oxide hydrogel particles as measured by the Archimedes method (3.869 g / cm³ in the case of zirconia gel). 3 The ratio of ). In addition, the measured density (hereinafter also simply referred to as "density") is the bulk density measured according to the size method.

[0011] Solution for solving the problem

[0012] The inventors have discovered that, compared to using composite particles (made by coating the surface of barium zirconate particles with zirconium oxide gel) as described in Non-Patent Document 1, if only zirconium oxide gel is used, that is, particles formed by a gel containing at least one oxide selected from Ti, Zr and Hf, a dense perovskite-type ceramic molded body with high relative density is obtained.

[0013] The present invention is as follows.

[0014] (1) A method for manufacturing a perovskite-type ceramic molded body, characterized in that it is a method for manufacturing a molded body formed from a perovskite-type ceramic containing an alkaline earth metal element, at least one element selected from Ti, Zr and Hf, and oxygen, wherein the manufacturing method comprises the following contact reaction step:

[0015] A precursor molded body containing a gel having an oxide selected from Ti, Zr, and Hf is brought into contact with a liquid containing a hydroxide of the aforementioned alkaline earth metal element.

[0016] (2) The method for manufacturing perovskite-type ceramic molded body according to (1) above, wherein the gel is amorphous.

[0017] (3) The method for manufacturing perovskite-type ceramic molded body according to (1) or (2) above, wherein the precursor molded body is a powder molded body of particles formed from the gel above.

[0018] (4) The method for manufacturing a perovskite-type ceramic molded body according to any one of (1) to (3) above, wherein the precursor molded body is a powder-pressed body of a mixture of particles formed from the gel and particles formed from the perovskite-type ceramic.

[0019] (5) A perovskite ceramic molded body, characterized in that the aggregate of perovskite ceramic crystals forms crystal domains and multiple crystal domains are connected together, the perovskite ceramic crystals contain alkaline earth metal elements, at least one element selected from Ti, Zr and Hf and oxygen, and the relative density of the perovskite ceramic molded body is 60% or more.

[0020] (6) The perovskite-type ceramic molded body according to (5) above, wherein the above-mentioned crystal domains include a plurality of the above-mentioned perovskite-type ceramic crystals oriented in the same direction.

[0021] (7) A raw material for a precursor molding body for manufacturing a perovskite-type ceramic molded body, characterized in that it is the raw material for a precursor molding body used in any one of the above-described (1) to (4) methods for manufacturing a perovskite-type ceramic molded body.

[0022] It comprises particles formed from a gel containing at least one oxide selected from Ti, Zr and Hf.

[0023] (8) The raw material for the precursor molding body for manufacturing perovskite-type ceramic molding body according to (7) above, wherein the gel is amorphous.

[0024] (9) The raw material for manufacturing a precursor molded body for perovskite-type ceramic molded body according to (7) or (8) above, wherein the volume average particle size of the gel particles is 0.05 to 10 μm.

[0025] The effects of the invention

[0026] According to the present invention, perovskite-type ceramic molded bodies containing crystals (perovskite-type ceramic crystals) formed from desired perovskite-type oxides with high density (relative density of 60% or more) can be manufactured efficiently and economically, such that the contact reaction process does not require high temperatures of 1000°C or higher, i.e., no large amount of thermal energy is needed. In a preferred embodiment, the relative density can be 80% or more.

[0027] According to the present invention, the above-mentioned dense perovskite-type ceramic molded body can be used as a dielectric for ceramic capacitors, an electrolyte for solid oxide fuel cells, an electrolyte for gas sensors, an electrode or electrolyte for all-solid-state batteries, a photocatalytic electrode, etc. Attached Figure Description

[0028] Figure 1 A schematic diagram illustrating an example of the crystal structure of the perovskite-type ceramic molded body of the present invention.

[0029] Figure 2 A schematic diagram illustrating another example of the crystal structure of the perovskite-type ceramic molded body of the present invention.

[0030] Figure 3 A graph showing the particle size distribution of the raw material particles X1 used in the [Example].

[0031] Figure 4 A graph showing the particle size distribution of the raw material particles X2 used in the [Example].

[0032] Figure 5 The image shows the SEM image of the precursor P1 used in Experiment Example 1.

[0033] Figure 6 The image shows the SEM image of the perovskite ceramic molded body Q1 obtained in Experiment Example 1.

[0034] Figure 7 for Figure 6 A magnified image.

[0035] Figure 8 This is a high-magnification FE-SEM image of the perovskite-type ceramic molded body Q1 obtained in Experiment Example 1.

[0036] Figure 9 for Figure 8 A magnified image.

[0037] Figure 10 This is a diagram showing the crystal orientation mapping of the perovskite-type ceramic molded body Q1 obtained in Experimental Example 1.

[0038] Figure 11 A graph showing the relative densities of the perovskite-type ceramic molded bodies Q1 to Q8 obtained in Experimental Examples 1 to 8.

[0039] Figure 12 The image shows the SEM image of the perovskite ceramic molded body Q8 obtained in Experiment Example 8.

[0040] Figure 13 This is a SEM image of the precursor P2 used in Experiment Example 9.

[0041] Figure 14 The image shows the SEM image of the perovskite ceramic molded body R1 obtained in Experiment Example 9.

[0042] Figure 15 The image shows the SEM image of the precursor P10 used in Experiment Example 12.

[0043] Figure 16 The image shows the SEM image of the perovskite ceramic molded body S1 obtained in Experiment Example 12.

[0044] Figure 17 for Figure 16 A magnified image.

[0045] Figure 18The image shows the X-ray diffraction pattern of the perovskite ceramic obtained in Experiment Example 13. Detailed Implementation

[0046] In this invention, the perovskite ceramic is a general formula M containing an alkaline earth metal element, at least one element selected from Ti, Zr, and Hf, and oxygen. 1 M 2 O3 (where M is in the formula) 1 M is an alkaline earth metal element. 2 The oxide of the element (selected from at least one element selected from Ti, Zr, and Hf). Alkali earth metal element M. 1 The preferred elements are Ca, Sr, and Ba.

[0047] The method for manufacturing perovskite-type ceramic molded articles of the present invention includes the following contact reaction step: contacting a precursor molded article containing a gel containing at least one oxide selected from Ti, Zr and Hf with a liquid containing a hydroxide of the aforementioned alkaline earth metal element, and a post-processing step may be included as needed (described later).

[0048] The precursor molding used in the above-described contact reaction process is an article that contains only the gel. "Contains only the gel" does not mean "composed solely of gel" without other components, but rather, when other components are included, for example, a complex is formed by dispersing other components within a gel matrix. As a result, it sometimes loses its "contains only the gel" composition, and such complexes are excluded. Therefore, the precursor molding of the present invention is an article that requires the gel and optionally contains other components. In the present invention, the preferred precursor molding is a powder-molded article formed by pressing a raw material containing granulated gel (hereinafter referred to as "particles formed from gel" or "gel particles") (referring to the "precursor raw material for manufacturing perovskite-type ceramic molded articles" of another present invention, hereinafter referred to as "precursor raw material") into powder. It should be noted that, from the viewpoint of the formability of molded articles formed from high-density perovskite-type ceramic crystals, the gel is preferably amorphous. Furthermore, the general formula M is commonly used... 2 O2·nH2O (where n is a positive number) represents this.

[0049] The shape of the aforementioned gel particles is not particularly limited; for example, they can be spherical (including approximately spherical), ellipsoidal, linear, plate-like, etc. The shape of the gel particles contained in the precursor raw material and the precursor molded body does not need to be the same in all particles; there may be only one of the aforementioned shapes, or there may be two or more of them.

[0050] Furthermore, the size of the aforementioned gel particles is not particularly limited. From the perspective of obtaining a high-density precursor molded body, the maximum length is preferably 100 μm, more preferably 1 μm. The minimum length is preferably 1 nm, more preferably 30 nm. In the case of spherical gel particles, the volume average particle size based on laser diffraction is preferably 0.01 to 10 μm, more preferably 0.05 to 1 μm.

[0051] The aforementioned precursor materials can be formed from gel particles, or from gel particles and other components. In the latter case, the other components are preferably inorganic compounds modified without being subjected to a liquid containing an alkaline earth metal hydroxide. For example, oxides, sulfides, carbides, nitrides, alkali-resistant metals, etc., can be formed, preferably oxides, more preferably perovskite ceramics, and particularly preferably the perovskite ceramic to be manufactured. The other components can be crystalline or amorphous, either is acceptable. Furthermore, the shape and size of the other components are preferably those described above in the gel particles.

[0052] When the precursor material is formed from gel particles and other components, the total mass of the precursor material is set to 100% by mass, and the lower limit of the content of gel particles is preferably 30% by mass, more preferably 50% by mass.

[0053] When producing a pressed powder molded body (precursor molded body) by compression molding, it is preferable to perform the process at a temperature above 10°C and below 150°C to suppress gel modification. The compression molding process can be performed using a method that leads to high density, depending on the shape of the precursor molded body. In this invention, for example, a method of sequentially performing uniaxial molding and cold isostatic pressing (CIP) can be applied. By using compression molding of gel particles, the gel particles undergo plastic deformation, which allows for high density of the precursor molded body.

[0054] The relative density of the above-mentioned pressed powder molded body (precursor molded body) is preferably 45-75%, more preferably 60-75%.

[0055] In the contact reaction process of this invention, a liquid containing a hydroxide of an alkaline earth metal element is used. Examples of such hydroxides include calcium hydroxide, strontium hydroxide, and barium hydroxide. The liquid may contain only one type of hydroxide or two or more types.

[0056] Examples of media contained in the aforementioned liquid include water and alcohols containing water. Furthermore, the liquid may contain other components such as organic compounds, provided that it does not impede the reaction between the gel constituting the precursor molded body and the aforementioned hydroxide.

[0057] The liquid is preferably a saturated aqueous solution of an alkaline earth metal hydroxide.

[0058] The contact method in the above-described contact reaction process is appropriately selected based on the shape and size of the precursor molded body, and is not particularly limited. Examples of contact methods include: immersing the precursor molded body in the liquid; spraying the liquid onto the precursor molded body; coating the precursor molded body with the liquid; etc. Among these, immersing the precursor molded body in the liquid is preferred from the perspective of efficiently obtaining a molded body containing high-density perovskite-type ceramic crystals.

[0059] When the above liquid comes into contact with the precursor molded body, in order to ensure that the reaction between the hydroxide contained in the above liquid and the gel proceeds smoothly without dissolving the precursor molded body, that is, without dissolving the gel contained in the precursor molded body, the upper limit of the contact temperature is preferably 200°C, more preferably 180°C, and even more preferably 160°C, and the lower limit is preferably 20°C, more preferably 50°C, and even more preferably 75°C.

[0060] In addition, the contact time between the liquid and the precursor molded body is appropriately selected according to the shape and size of the precursor molded body, usually more than 12 hours, preferably more than 50 hours.

[0061] The method for manufacturing the perovskite-type ceramic molded body of the present invention, as described above, may include a post-processing step as needed after the contact reaction step. Examples of post-processing steps include: a cleaning step for removing the remaining liquid adhering to the perovskite-type ceramic molded body during the contact reaction step; a trimming step for adjusting the product shape and size; and a heat treatment step.

[0062] In the cleaning process, methods such as spraying water or an aqueous acetic acid solution onto the perovskite ceramic molded body containing liquid, or immersing the perovskite ceramic molded body in water or an aqueous acetic acid solution, followed by drying, can be used. When drying the perovskite ceramic molded body, it can be done under normal or reduced pressure conditions, preferably at 20–200°C, more preferably at 70–150°C.

[0063] In the finishing process, grinding, drilling, and surface polishing can be performed to adjust the product to a specified shape and size.

[0064] In the heat treatment process, in order to form the internal particles of the perovskite ceramic molded body, a process of heating at 500°C to 1500°C in an atmospheric atmosphere can be performed, for example.

[0065] The perovskite-type ceramic molded body obtained by the manufacturing method of the present invention is a high-density molded body containing crystals formed from perovskite oxides such as barium titanate, barium zirconate, strontium zirconate, barium calcium zirconate titanate, strontium titanate, and strontium hafnium oxide, and by-product carbonates without alkaline earth metals. As mentioned above, precursor materials formed from gel particles or precursor materials formed from gel particles and other components can be used, but in any case, the resulting molded body is dense. In addition, the ratio of the measured density to the theoretical density of the molded body obtained by the manufacturing method of the present invention, i.e., the relative density, is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more.

[0066] The perovskite-type ceramic molded body of the present invention, such as Figure 1 and Figure 2 The diagram shows an aggregate of perovskite-type ceramic crystals 1 (in the diagram, only a portion of the hexagonal portion is shown with diagonal lines) forming crystal domains 2, and multiple crystal domains 2 being connected together. Figure 1 This is a schematic diagram illustrating the crystal structure of a perovskite-type ceramic molded body obtained from a precursor molded body made from a precursor material formed from gel particles. Figure 2 This is a schematic diagram illustrating the crystal structure of a perovskite-type ceramic molded body obtained from a precursor molded body made from a precursor material formed from gel particles and other components. Furthermore, multiple crystals contained within a single crystal domain... Figure 1 and Figure 2 As illustrated by arrows, crystals can be formed with the same orientation. The crystal size is preferably 1–200 nm, more preferably 10–100 nm.

[0067] The perovskite-type ceramic molded body of the present invention has Figure 1 and Figure 2 Such a crystal structure, comprising multiple interconnected domains 2, can be confirmed using EBSD analysis employing electron backscattering diffraction. Electrons generated by irradiating the molded body with an electron beam undergo inelastic scattering and are diffracted at the lattice planes. Reflected electrons, as diffraction patterns with a so-called EBSD diagram, are released. Therefore, by projecting these patterns and assigning orientation indices, the crystal orientation can be obtained. Scanning the electron beam and mapping the EBSD diagram, for example, yields an inverse pole diagram crystal orientation mapping, thereby confirming the orientation of crystal 1 and the domains 2 formed by their aggregation. The perovskite-type ceramic molded body of the present invention, by having this structure, is believed to reduce fluctuations in ion conduction and polarization direction, resulting in various functional improvements as described later.

[0068] The perovskite-type ceramic molded body of the present invention is obtained by the manufacturing method of the present invention described above, which does not require a process of forming a temperature of 1500°C or higher during conventional sintering manufacturing, i.e., does not require a large amount of heat energy. It can form a molded body with a high relative density, and therefore is suitable as a constituent material for dielectric elements, ion conduction elements, electrical conduction elements, piezoelectric elements, strong dielectric elements, strong magnetic elements, and photocatalysts.

[0069] Example

[0070] The following describes a manufacturing example of a perovskite-type ceramic molded body.

[0071] 1. Raw materials for manufacturing perovskite-type ceramic molded bodies

[0072] The following shows the alkaline earth metal hydroxides used in the manufacture of the molded articles and the raw material particles used as raw materials for the manufacture of the precursor molded articles.

[0073] (1) Hydroxides of alkaline earth metals

[0074] Barium hydroxide octhydrate was prepared using FUJIFILM Wako Pure Chemical Corporation.

[0075] (2) Raw material particles X1 and X2

[0076] Zirconium oxychloride prepared by FUJIFILM Wako Pure Chemical Corporation was added to ion-exchanged water and stirred to obtain an aqueous solution. Ammonia was then added to this aqueous solution, and the reaction was carried out at room temperature to obtain a reaction product containing an oxide hydrogel formed from ZrO2·nH2O. Subsequently, to remove byproducts, the oxide hydrogel was recovered by filtration and washing with water. Then, it was dried at 150°C for 12 hours to obtain a solidified gel. The solidified gel was evaluated by X-ray diffraction; no diffraction peaks originating from crystals were observed, therefore, it was determined to be amorphous.

[0077] Next, the solidified gel was pre-pulverized using a pestle and mortar. Then, the pre-pulverized material and ethanol were mixed at a mass ratio of 10:90, and an equal volume of zirconia balls (5 mm in diameter) and the mixture were sealed into a polyethylene container. The container was then rotated at 150 rpm for 10 hours to pulverize the solidified gel, and the mixture containing the pulverized material (precursor material, hereinafter referred to as "raw material particles X1") was recovered. Next, an equal volume of zirconia balls (0.5 mm in diameter) and the mixture were sealed into a zirconia grinding vessel. Then, a planetary ball mill was used to pulverize the mixture at 450 rpm for 3 hours, and the mixture containing the pulverized particles was recovered. Next, an equal volume of zirconia balls (0.1 mm in diameter) and the mixture were sealed into a zirconia grinding vessel. Then, a planetary ball mill was used to pulverize the mixture at 450 rpm for 3 hours to obtain a mixture containing the pulverized particles (precursor material, hereinafter referred to as "raw material particles X2").

[0078] Ethanol was removed from the mixtures containing raw material particles X1 and X2. These particles were then washed, recovered, and dried at 150°C. The particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring device “LA-960V2” (model name) manufactured by Horiba Corporation (see reference). Figure 3 and Figure 4 Average particle size d 50 The following are the characteristics of raw material particles: X1 is 2.182 μm and X2 is 0.083 μm.

[0079] (3) Raw material particles Y1

[0080] According to Yuki Yamaguchi, J.Ceram.Soc.Jpn., 128

[10] (2020)747-755, barium zirconate synthesized by solution method was calcined at 1300°C for 10 hours in an atmospheric atmosphere. Then, the powder obtained by pulverization and zirconium oxychloride prepared by FUJIFILM Wako Pure Chemical Corporation were added to ion-exchange water and stirred to prepare an aqueous solution containing barium zirconate particles. Then, ammonia water was added dropwise to the aqueous solution and the reaction was carried out at room temperature to obtain ZrO2·nH2O. The oxide hydrogel-covered composite particles formed by the obtained ZrO2·nH2O were used as raw material particles Y1. The particle size distribution of the raw material particles Y1 was measured, and the average particle size d was found to be 0. 50 It is 6.921 μm.

[0081] 2. Manufacturing and evaluation of molded parts

[0082] The aforementioned raw material particles were subjected to uniaxial pressure molding and cold isostatic pressing to obtain a circular plate-shaped precursor (20 mm in diameter, 0.5–1.0 mm in thickness). This precursor was then immersed in a saturated aqueous solution of barium hydroxide octhydrate to obtain a molded body formed from barium zirconate crystals, which are perovskite-type ceramics. The density of the obtained molded body was then measured, and the density was compared with the apparent density of the oxide hydrogel (3.869 g / cm³). 3 The theoretical density of barium zirconate (6.117 g / cm³) and barium zirconate. 3 The relative density is calculated from the ratio of ).

[0083] Experimental Example 1

[0084] Two 0.5 g samples of raw material particles (oxide hydrogel particles) were subjected to uniaxial compression molding (20 kN) and cold isostatic pressing (300 MPa) to obtain a precursor (hereinafter referred to as "precursor P1"). The density of precursor P1 was 2.717 g / cm³. 3 Its relative density is 71.38%.

[0085] Next, the precursor molded body P1 was immersed in a saturated aqueous solution of 20g of barium hydroxide octhydrate in a container. The mixture was then left to stand at 100°C for 100 hours under sealed conditions. Afterward, it was cleaned with an aqueous solution based on water and acetic acid, and dried at 150°C in an atmospheric atmosphere to obtain a perovskite-type ceramic molded body (hereinafter referred to as "molded body Q1") formed from dense barium zirconate crystals. The density of molded body Q1 is 5.138 g / cm³. 3 The relative density is 84.00% (refer to Table 1).

[0086] The fracture surface of the precursor P1 was observed using a scanning electron microscope, and the results were obtained. Figure 5 The image. According to... Figure 5 It can be seen that the interior of the precursor P1 is densely aggregated into fine particles, exhibiting a smooth structure. Furthermore, based on the fracture surface of the molded body Q1 observed using a scanning electron microscope, the results show... Figure 6 and Figure 7 The image. According to... Figure 6 Therefore, it can be seen that coarse particles and pores do not exist. Figure 7 for Figure 6 The magnified image, according to this Figure 7 It can be seen that a dense shaped body formed by fine crystals was obtained.

[0087] Next, the fracture surface of molded body Q1 was observed using a field emission scanning electron microscope "JSM-6330F" (model name) manufactured by Nippon Electron Ltd., and the results were obtained. Figure 8 and Figure 9According to Figure 8 Enlarged image Figure 9 It can be seen that crystal particles with a size of 10–100 nm aggregate to form crystal domains with a size of 0.5–10 μm. Furthermore, it can be seen that adjacent crystal domains are interconnected, exhibiting a three-level hierarchical structure. On the other hand, a sample for EBSD measurement was prepared by grinding the fracture surface of the molded body Q1. The microstructure was observed using a JSM-6500F (model name) heated field emission scanning electron microscope manufactured by Nippon Electron Ltd., and the crystal orientation mapping of barium zirconate was determined. The results were... Figure 10 .according to Figure 10 Therefore, Figure 8 and Figure 9 The observed crystal particles with sizes of 10–100 nm aggregated, and the crystal orientations within the resulting 0.5–10 μm crystal domains all showed the same direction. Therefore, the crystal particles with sizes of 10–100 nm within the crystal domains were oriented and aggregated.

[0088] Experimental Examples 2-4

[0089] Instead of 100 hours, the reaction time (immersion time of precursor molded body P1 in a saturated aqueous solution of barium hydroxide octhydrate) was changed to 12 hours, 50 hours, and 200 hours, respectively. Otherwise, the same operation as in Experimental Example 1 was performed to obtain perovskite-type ceramic molded bodies (hereinafter referred to as "molded bodies Q2 to Q4"). Then, the relative densities of these molded bodies Q2 to Q4 were calculated (refer to Table 1).

[0090] Experimental Examples 5-8

[0091] The reaction temperature was changed to 150°C instead of 100°C, and the reaction times were set to 12 hours, 70 hours, 100 hours, and 200 hours, respectively. Otherwise, the same procedures as in Experimental Example 1 were performed to obtain perovskite-type ceramic molded bodies (hereinafter referred to as "molded bodies Q5 to Q8"). Then, the relative densities of these molded bodies Q5 to Q8 were calculated (refer to Table 1 and...). Figure 11 Based on the surface of the molded body Q8 observed by electron microscopy, the results were obtained. Figure 12 The image. According to this... Figure 12 It can be seen that it is a dense shaped body formed by fine crystals.

[0092] [Table 1]

[0093] Table 1

[0094]

[0095] Experimental Example 9

[0096] Using raw material particles X1 (oxide hydrogel particles) instead of raw material particles X2, the same operation as in Experimental Example 1 was performed to prepare a precursor molded body (hereinafter referred to as "precursor molded body P2"). Then, it was immersed in a saturated aqueous solution of barium hydroxide 8 hydrate as in Experimental Example 1. After that, it was washed and dried to obtain a perovskite-type ceramic molded body (hereinafter referred to as "molded body R1") formed of dense barium zirconate crystals.

[0097] The density of the precursor P2 is 2.646 g / cm³. 3 The relative density is 69.50%. Additionally, the density of the obtained molded body R1 is 4.285 g / cm³. 3 Its relative density is 70.05%.

[0098] Based on electron microscopy observation of the fracture surface of the precursor P2, the results were obtained. Figure 13 The image. According to... Figure 13 It can be seen that large and fine particles are mixed within the precursor P2, and these particles are densely aggregated, exhibiting a smooth texture. Furthermore, based on electron microscopy observation of the fracture surface of the molded body R1, the results show... Figure 14 The image. According to this... Figure 14 It can be seen that it is a dense shaped body formed by fine crystals.

[0099] Experimental Example 10

[0100] The powder particles were obtained by pulverizing the molded body R1 and heat-treating it at 1300°C for 10 hours in an atmospheric atmosphere using 52.6% by mass of raw material particles X1 and 47.4% by mass of barium zirconate particles (with an average particle size d). 50 A mixture of 0.969 μm and a precursor molded body (hereinafter referred to as "precursor molded body P3") was prepared by performing the same operation as in Experimental Example 1. Then, it was similarly immersed in a saturated aqueous solution of barium hydroxide 8 hydrate, and then washed and dried to obtain a perovskite-type ceramic molded body (hereinafter referred to as "molded body R2") formed of dense barium zirconate crystals.

[0101] The relative density of the precursor P3 is 61.25%. Furthermore, the relative density of the resulting molded body R2 is 73.80%.

[0102] Experimental Example 11

[0103] The powder particles were obtained by pulverizing the molded body R1 and heat-treating it at 1300°C for 10 hours in an atmospheric atmosphere using 82.0% by mass of raw material particles X1 and 18.0% by mass of barium zirconate particles (with an average particle size d). 50A mixture of 0.969 μm and other materials was prepared, and the same procedure as in Experimental Example 1 was performed to prepare a precursor molded body (hereinafter referred to as "precursor molded body P4"). Then, it was similarly immersed in a saturated aqueous solution of barium hydroxide 8 hydrate, and then washed and dried to obtain a perovskite-type ceramic molded body (hereinafter referred to as "molded body R3") formed of dense barium zirconate crystals.

[0104] The relative density of the precursor P4 was 61.39%. Additionally, the density of the resulting molded part R3 was 4.569 g / cm³. 3 Its relative density is 74.69%.

[0105] Experimental Example 12 (Comparative Example)

[0106] Using raw material particles Y1 (composite particles) instead of raw material particles X2, the same operation as in Experimental Example 1 was performed to prepare a precursor molded body (hereinafter referred to as "precursor molded body P10"). Then, it was immersed in a saturated aqueous solution of barium hydroxide 8 hydrate as in Experimental Example 1. After that, it was washed and dried to obtain a perovskite-type ceramic molded body (hereinafter referred to as "molded body S1") formed of dense barium zirconate crystals.

[0107] The density of the precursor P10 is 2.579 g / cm³. 3 The relative density is 53.26%. Additionally, the density of the obtained molded body S1 is 3.291 g / cm³. 3 Its relative density is 53.80%.

[0108] Based on electron microscopy observation of the fracture surface of the precursor P10, the results were obtained. Figure 15 The image. According to... Figure 15 It can be seen that it is composed of a rough structure. Furthermore, based on the surface of the molded body S1 observed under an electron microscope, the results show... Figure 16 and Figure 17 The image. According to... Figure 16 Therefore, it can not be obtained as a dense substance, forming a brittle structure. Figure 17 for Figure 16 The magnified image, according to this Figure 17 As can be seen, a molded body with a large number of pores was obtained.

[0109] Experimental Example 13

[0110] Using the general formula M 2 O2·nH2O (where M is the formula) 2Each precursor molded body obtained from particles of gel formed from TiO2·nH2O or HfO2·nH2O, and strontium or barium hydroxide, was subjected to the same procedure as in Experimental Example 1 at a reaction temperature of 100°C and a reaction time of 12 hours. Figure 18 The X-ray diffraction patterns of various perovskite-type ceramic molded bodies are shown. Based on... Figure 18 It can be seen that, similar to barium zirconate, strontium titanate, barium titanate, strontium hafnium oxide, and barium hafnium oxide were obtained.

[0111] Industrial availability

[0112] The perovskite-type ceramic molded body of the present invention is a dense material, and therefore can be used as a dielectric for ceramic capacitors, an electrolyte for solid oxide fuel cells, an electrolyte for gas sensors, an electrode or electrolyte for all-solid-state batteries, a photocatalytic electrode, etc.

[0113] Explanation of reference numerals in the attached figures

[0114] 1: Crystal

[0115] 2: Crystal domains

[0116] 3: Other ingredients

Claims

1. A method for manufacturing a perovskite-type ceramic molded body, characterized in that, It is a method for manufacturing a molded body made of perovskite-type ceramic containing an alkaline earth metal element, at least one element selected from Ti, Zr and Hf, and oxygen, wherein the manufacturing method comprises the following contact reaction step: A precursor molded body comprising a gel containing at least one oxide selected from Ti, Zr, and Hf and water is brought into contact with a liquid containing a hydroxide of the alkaline earth metal element.

2. The method for manufacturing a perovskite-type ceramic molded body according to claim 1, wherein, The gel is amorphous.

3. The method for manufacturing a perovskite-type ceramic molded body according to claim 1 or 2, wherein, The precursor molding body is a powder molding body formed from particles formed by the gel.

4. The method for manufacturing a perovskite-type ceramic molded body according to claim 1 or 2, wherein, The precursor molded body is a powder-pressed molded body consisting of particles formed from the gel and particles formed from the perovskite ceramic.

5. A method for manufacturing a perovskite-type ceramic molded body, characterized in that, It is a method for manufacturing the perovskite-type ceramic molded body as described in claim 1 or 2. The precursor molding is obtained using a raw material comprising particles formed from a gel containing at least one oxide selected from Ti, Zr, and Hf and water.

6. The method for manufacturing a perovskite-type ceramic molded body according to claim 5, wherein, The gel is amorphous.

7. The method for manufacturing a perovskite-type ceramic molded body according to claim 5 or 6, wherein, The volume average particle size of the gel particles is 0.05~10μm.

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