Strontium zirconate-based powder and method for producing the same

Abstract

To provide strontium zirconate-based powder that is fine, has high dielectric constants, and shows superior reactivity (contractility) upon sintering, a molded product thereof, a sintered product, and a method for producing the same.SOLUTION: A strontium zirconate-based powder has a BET specific surface area of 90.0 m2 / g or more and 200.0 m2 / g or less and includes more than 50 at% of strontium atoms at the A site of the perovskite structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a strontium zirconate-based powder and a method for producing the powder. [Background technology]

[0002] Strontium zirconate and its solid solution powder (collectively referred to as "strontium zirconate-based powder" in this invention) are used as dielectric materials for multilayer ceramic capacitors (MLCCs). In recent years, various electronic components have been increasingly miniaturized and increased in capacity. Consequently, MLCCs require miniaturization of the dielectric material and thinning of the dielectric film.

[0003] Methods for producing strontium zirconate-based powders include, for example, solid-phase methods and hydrothermal methods. A common solid-phase method involves heating a mixture of fine strontium carbonate powder and fine zirconium oxide powder to induce a solid-phase reaction.

[0004] Furthermore, as a hydrothermal method, for example, Patent Document 1 describes a first step of hydrothermally reacting a hydrated oxide of a group B element (Zr) to dehydrate it, and then hydrothermally reacting the reaction product of the group B element with a hydroxide of a group A element (Sr) in an aqueous medium to produce an average particle size of 70 nm and a specific surface area of ​​16 m². 2 It is stated that strontium zirconate can be obtained. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-120850 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In order to obtain fine strontium zirconate powder using the solid-phase method described above, the raw materials, strontium carbonate powder and zirconium oxide powder, must themselves be fine, and the cost burden of preparing and supplying such fine raw material powders is significant.

[0007] On the other hand, even by the hydrothermal method described in Patent Document 1 above, the specific surface area of ​​the composition obtained is 16 m². 2 The average particle size is 70 nm, making it difficult to obtain finer strontium zirconate powder. Furthermore, grinding the strontium zirconate powder produced by this hydrothermal method requires significant energy and cost, making it difficult to obtain a uniform, fine powder with few impurities.

[0008] This invention was made under such circumstances and aims to provide a strontium zirconate-based powder that is fine, has a high dielectric constant, and exhibits excellent reactivity (shrinkage) during sintering, as well as molded articles thereof, sintered articles thereof, and a method for manufacturing the same. Because the strontium zirconate-based powder has a high dielectric constant and excellent reactivity (shrinkage) during sintering, it is suitable as a material for ceramic capacitors. [Means for solving the problem]

[0009] This invention is based on the discovery that a strontium zirconate-based powder that is fine, has a high dielectric constant, and exhibits excellent reactivity during sintering can be obtained, and on the discovery of a suitable manufacturing method for obtaining such a strontium zirconate-based powder.

[0010] In other words, the present invention provides the following [1] to

[15] . [1] BET specific surface area 90.0m 2 / g or more 200.0m 2 A strontium zirconate-based powder containing more than 50 at% strontium atoms at the A site of the perovskite structure, with a concentration of less than / g. [2] A strontium zirconate-based powder as described in [1] above, having an average primary particle size of 5.0 to 50.0 nm. [3] A solid solution containing at least one metal atom (A) selected from barium atoms and calcium atoms, wherein the total content of the metal atom (A) is less than 1.0 mol with respect to 1 mol of strontium atoms, the strontium zirconate-based powder according to [1] or [2] above. [4] A solid solution containing at least one metal atom (B) selected from titanium atoms, hafnium atoms and cerium atoms, wherein the total content of the metal atom (B) is less than 1.0 mol with respect to 1 mol of zirconium atoms, the strontium zirconate-based powder according to any one of [1] to [3] above. [5] The content of strontium atoms is 0.05 to 2.0 mol with respect to 1 mol of zirconium atoms, the strontium zirconate-based powder according to any one of [1] to [4] above.

[0011] [6] The atoms contained in the A site of the perovskite structure are only strontium atoms, the strontium zirconate-based powder according to any one of [1] to [5] above. [7] A method for producing a strontium zirconate-based powder, comprising: (1) A step of preparing an aqueous slurry containing zirconium atoms at 90°C or lower; (2) A step of adding an additive raw material containing a strontium compound to the aqueous slurry containing zirconium atoms to obtain a raw material mixture; (3) A step of wet-grinding the raw material mixture to obtain a grinding slurry; (4) A step of drying the grinding slurry at 400°C or lower to obtain a dried powder; (5) A step of firing the dried powder at a temperature of 600°C or higher and lower than 800°C to obtain a fired powder; (6) A step of wet-grinding the fired powder using an organic dispersion medium and then drying it to obtain a strontium zirconate-based powder. A method for producing a strontium zirconate-based powder. [8] The aqueous slurry containing zirconium atoms is at least one selected from the following (1a) and (1b): (1a) A slurry obtained by neutralizing an aqueous zirconium salt solution and removing the resulting salt (1b) A slurry obtained by adding zirconium hydroxide to water The strontium compound is one or more selected from strontium carbonate, strontium hydroxide, strontium oxide, and strontium peroxide, In the raw material mixture, the content of strontium atoms is 0.05 to 2.0 moles per 1 mole of zirconium atoms, and the total content of any one or more metal atoms (A) selected from barium atoms and calcium atoms is 1.0 mole or less per 1 mole of strontium atoms. The total content of any one or more metal atoms (B) selected from titanium atoms, hafnium atoms, and cerium atoms is 1.0 mole or less per 1 mole of zirconium atoms. The method for producing strontium zirconate-based powder according to [7] above. [9] The method for producing strontium zirconate-based powder according to [8] above, wherein the added raw material added in the step (2) contains a compound having the metal atom (A).

[10] The method for producing strontium zirconate-based powder according to [8] or [9] above, wherein the added raw material added in the step (2) contains a compound having the metal atom (B).

[0012]

[11] The method for producing strontium zirconate-based powder according to any one of [8] to

[10] above, wherein the neutralizing agent used for neutralizing the aqueous zirconium salt solution in (1a) is one or more selected from calcium hydroxide, barium hydroxide, strontium hydroxide, and ammonia.

[12] The method for producing strontium zirconate-based powder according to any one of [8] to

[11] above, wherein the zirconium salt in (1a) is one or more selected from zirconium oxychloride octahydrate and zirconium nitrate dihydrate.

[13] The method for producing strontium zirconate-based powder according to any one of [7] to

[12] above, wherein in the step (2), an organic polymer-based dispersant is further added to obtain the raw material mixture.

[14] A molded article of strontium zirconate powder as described in any one of the above items [1] to [6].

[15] A sintered product of strontium zirconate powder as described in any one of the above items [1] to [6]. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a strontium zirconate-based powder that is fine, has a high dielectric constant, and exhibits excellent reactivity during sintering. Furthermore, since the manufacturing method of the present invention yields a strontium zirconate-based powder with good crushability, it is possible to efficiently obtain a fine strontium zirconate-based powder. [Brief explanation of the drawing]

[0014] [Figure 1] This is a chart of the X-ray diffraction spectrum for Example 1. [Figure 2] This is a chart of the X-ray diffraction spectrum for Example 2. [Figure 3] This is a chart of the X-ray diffraction spectrum for Example 3. [Figure 4] This is a chart of the X-ray diffraction spectrum for Example 4. [Figure 5] This is a chart of the X-ray diffraction spectrum for Comparative Example 1. [Figure 6] This is a chart of the X-ray diffraction spectrum for Comparative Example 2. [Figure 7] This is a chart of the X-ray diffraction spectrum for Comparative Example 3. [Modes for carrying out the invention]

[0015] The following describes in detail embodiments of the strontium zirconate powder and its manufacturing method according to the present invention. In addition, the strontium zirconate-based powder in the present invention includes, in addition to strontium zirconate (SrZrO3) powder, strontium zirconate powder containing a predetermined metal atom other than zirconium and strontium (hereinafter sometimes referred to as a solid solution). However, the strontium zirconate-based powder shall contain more than 50 at% of strontium atoms at the A site of the perovskite structure. If the strontium atoms are not contained more than 50 at% at the A site, that is, if the strontium atoms are 50 at% or less, the dielectric constant cannot be increased. Also, as used in this specification, the term "room temperature" means a normal temperature of 25 ± 5°C.

[0016] [Strontium zirconate-based powder] The strontium zirconate-based powder of this embodiment has a BET specific surface area of 90.0 m 2 / g or more and 200.0 m 2 / g or less, and is a strontium zirconate-based powder containing more than 50 at% of strontium atoms at the A site of the perovskite structure. Such a strontium zirconate-based powder is fine, and a molded product obtained using the strontium zirconate-based powder has a high dielectric constant. Therefore, the strontium zirconate-based powder can be suitably used as a raw material in various applications such as ceramic capacitors, piezoelectric elements, oxygen sensors, abrasives, catalysts, etc., by taking advantage of such characteristics. In particular, it is suitable as a dielectric material for electronic components.

[0017] (BET specific surface area) The BET specific surface area is 90.0 m 2 / g or more and 200.0 m 2 / g or less, preferably 100.0 to 150.0 m 2 / g, more preferably 103.0 to 120.0 m 2 / g. When the BET specific surface area is 90 m 2If the value is less than / g, it cannot sufficiently achieve the fineness required for the raw materials of dielectric materials such as ceramic capacitors. Furthermore, the upper limit of the BET specific surface area is 200.0m² from the viewpoint of practicality and ease of handling. 2 It is less than / g. In this invention, the BET specific surface area is a value measured by the BET flow method (3-point method) using nitrogen gas as the adsorbate, in accordance with JIS R 1626:1996. Specifically, it is the value measured by the fully automated BET specific surface area measuring device described in the following examples. This BET specific surface area is an indicator of the fineness of the strontium zirconate-based powder, and the larger the value of this BET specific surface area, the finer the strontium zirconate-based powder is considered to be.

[0018] (Average primary particle size) As described above, the strontium zirconate powder of this embodiment has a large BET specific surface area and is fine, and the particle size is preferably such that the average primary particle diameter is 5.0 to 50.0 nm, more preferably 10.0 to 30.0 nm, and even more preferably 15.0 to 20.0 nm. Such fine strontium zirconate powder is suitable as a dielectric material for ceramic capacitors and the like. In this invention, the average primary particle diameter is calculated by taking the arithmetic mean of the major and minor axes of any 20 particles in a transmission electron microscope (TEM) image of the sample powder, removing the 5 data points with the largest values ​​and the 5 data points with the smallest values, and then calculating the arithmetic mean of the remaining 10 data points. Specifically, it can be determined by the method described in the examples below.

[0019] (Crystal structure) The strontium zirconate-based powder has a perovskite-type crystal structure. This allows for a high dielectric constant.

[0020] In this invention, "having a perovskite crystal structure" means a compound having at least a strontium atom (Sr) at the A site of the perovskite structure and at least a zirconium atom (Zr) at the B site. Here, the A site refers to the 6-coordinate portion of the perovskite structure, and the B site refers to the 12-coordinate portion of the perovskite structure. The chemical formula is ABO3, where A represents the A site, B represents the B site, and O represents the oxygen atom. The presence of a perovskite crystal structure can be confirmed by the presence of a peak in the range of 29.5° to 33.0° in the powder X-ray diffraction spectrum of strontium zirconate powder using CuKα as a source. Furthermore, the presence of only one peak in this range confirms that it has only a perovskite crystal structure.

[0021] (solid solution) If the strontium zirconate-based powder is a solid solution, the solid solution may contain one or more metal atoms (A) selected from barium atoms (Ba atoms) and calcium atoms (Ca atoms) at the A site. Such solid solutions have a crystalline structure in which strontium atoms (Sr atoms) are partially substituted with metal atoms (A). That is, at least strontium (Sr) atoms are present at the A sites of the zirconate compound having a perovskite structure, but one or more of the above-mentioned metal atoms (A) may also be present.

[0022] Furthermore, if the strontium zirconate-based powder is a solid solution, the solid solution may contain one or more metal atoms (B) selected from titanium atoms (Ti atoms), hafnium atoms (Hf atoms), and cerium atoms (Ce atoms) at the B site. Such solid solutions have a crystalline structure in which zirconium atoms (Zr atoms) are partially substituted with metal atoms (B). That is, the B site of a zirconate compound having a perovskite structure contains at least zirconium (Zr) atoms, but may also contain one or more of the above-mentioned metal atoms (B). Furthermore, the strontium zirconate powder may be a solid solution containing metal atoms (A) and metal atoms (B).

[0023] The Sr atom content in the strontium zirconate-based powder is preferably 0.05 to 2.0 moles per mole of Zr atoms, more preferably 0.1 to 1.5 moles, even more preferably 0.2 to 1.0 moles, even more preferably 0.55 to 1.0 moles, and even more preferably 0.6 to 1.0 moles, from the viewpoint of maintaining the perovskite-type crystal structure in the strontium zirconate-based powder, even when the strontium zirconate-based powder is a solid solution as described above.

[0024] The composition of the strontium zirconate powder can be measured by X-ray fluorescence (XRF) analysis. Specifically, it can be determined by the method described in the examples below.

[0025] (Metal atom (A)) The metal atom (A) is a metal atom that constitutes the A site other than strontium, and is preferably one or more selected from calcium (Ca) atoms and barium (Ba) atoms. From the viewpoint of increasing the dielectric constant, the proportion of strontium atoms (Sr) in 100 at% of atoms contained in the A site of the perovskite structure is more than 50 at% and 100 at% or less, preferably 55 at% or more and 100 at% or less, more preferably 60 at% or more and 100 at% or less, even more preferably 70 at% or more and 100 at% or less, and even more preferably 80 at% or more and 100 at% or less. From a similar viewpoint, the total content of metal atoms (A) is preferably less than 1.0 mole, more preferably 0.8 moles or less, and even more preferably 0.7 moles or less, per mole of strontium atoms. The atoms contained in site A may consist solely of strontium atoms.

[0026] (Metal atom (B)) The metal atom (B) is a metal atom other than zirconium that constitutes the B site, and is preferably one or more selected from titanium (Ti) atoms, hafnium (Hf) atoms, and cerium (Ce) atoms. From the viewpoint of increasing the dielectric constant, the proportion of zirconium atoms (Zr) in 100 at% of atoms contained in the B site of the perovskite structure is preferably more than 50 at% and 100 at% or less, more preferably 60 at% to 100 at%, even more preferably 70 at% to 100 at%, and even more preferably 80 at% to 100 at%. From a similar viewpoint, the total content of metal atoms (B) is preferably less than 1.0 mole, more preferably 0.8 moles or less, even more preferably 0.5 moles or less, even more preferably 0.4 moles or less, and even more preferably 0.2 moles or less, per mole of zirconium atoms.

[0027] [Method for producing strontium zirconate-based powder] The strontium zirconate powder can be suitably produced by the manufacturing method of this embodiment, as described below. The above manufacturing method comprises the steps of: (1) preparing a zirconium atom-containing aqueous slurry at 90°C or below; (2) adding an additive raw material containing a strontium compound to the zirconium atom-containing aqueous slurry to obtain a raw material mixture; (3) wet grinding the raw material mixture to obtain a pulverized slurry; (4) drying the pulverized slurry at 400°C or below to obtain a dried powder; (5) calcining the dried powder at a temperature of 600°C or higher and less than 800°C to obtain calcined powder; and (6) wet grinding the calcined powder using an organic dispersion medium and then drying it to obtain the zirconate strontium powder. In this way, by mixing a zirconium atom-containing aqueous slurry with a strontium compound and wet grinding it, a strontium zirconate powder with good pulverizability can be obtained at a relatively low calcination temperature of less than 800°C. The strontium zirconate powder obtained by this hydrothermal method is obtained as a fine strontium zirconate powder.

[0028] (Process (1)) In step (1), a predetermined zirconium atom-containing aqueous slurry is prepared. In this invention, an aqueous slurry refers to a liquid in which the dispersion medium contains 90% by mass or more of water. Examples of the zirconium atom-containing aqueous slurry are (1a) and (1b) below. These may be used individually or in combination of two or more. (1a) Slurry obtained by neutralizing the zirconium salt aqueous solution and removing the resulting salt. (1b) Slurry obtained by adding zirconium hydroxide to water

[0029] When either slurry (1a) or (1b) is used, a calcined powder with good pulverizability is obtained, and the strontium zirconate-based powder obtained by wet grinding this calcined powder is a fine powder. Among these, when slurry (1a) is used, an even finer strontium zirconate-based powder can be obtained.

[0030] Specifically, the zirconium salts in (1a) above include zirconium oxychloride octahydrate (ZrCl2O·8H2O), zirconium nitrate dihydrate (ZrO(NO3)2·2H2O), zirconium sulfate tetrahydrate (ZrSO4·4H2O), and zirconium oxyacetate (ZrO(CH3COO)2). These may be used individually or in combination of two or more. Of these, zirconium oxychloride octahydrate and zirconium nitrate dihydrate are preferred.

[0031] From the viewpoint of safely and efficiently carrying out the neutralization reaction, the aqueous solution of the zirconium salt is preferably prepared so that the concentration of the zirconium salt is 0.05 to 1.0 mol / kg, more preferably 0.1 to 0.9 mol / kg, and even more preferably 0.2 to 0.8 mol / kg.

[0032] In the neutralization reaction described above, zirconium hydroxide is produced from the zirconium salt. By thoroughly neutralizing the zirconium salt to produce zirconium hydroxide, the hydrolysis reaction of the remaining zirconium salt during heating in a later step can be suppressed, preventing the growth of monoclinic zirconium oxide.

[0033] The neutralization reaction can be carried out, for example, by adding the entire amount of the neutralizing agent to an aqueous solution of the zirconium salt all at once, or by adding it in small amounts sequentially, and then stirring and mixing. Alternatively, the zirconium salt and the neutralizing agent may be added to water and mixed simultaneously. From the viewpoint of ease of operation, it is preferable to prepare an aqueous solution or dispersion (suspension) containing the entire amount of the neutralizing agent in advance, and then add this aqueous solution to the aqueous solution of the zirconium salt. In this case, although the concentration of the aqueous solution of the neutralizing agent depends on the solubility and dispersibility of the neutralizing agent used in water, from the viewpoint of carrying out the neutralization reaction safely and efficiently, it is generally preferable that the concentration is approximately the same as that of the aqueous solution of the zirconium salt.

[0034] As the neutralizing agent, a general alkali can be used, such as calcium hydroxide, barium hydroxide, strontium hydroxide, ammonia (water), etc. Furthermore, in order to obtain strontium zirconate powder with high purity, it is preferable not to use sodium hydroxide, which may contain sodium, an alkali metal, as an impurity. When producing strontium zirconate (SrZrO3) powder, the neutralizing agent is preferably strontium hydroxide and / or ammonia, and more preferably strontium hydroxide, from the viewpoint of suppressing impurities as much as possible. Furthermore, when producing a solid solution containing the aforementioned metal atom (A), barium hydroxide and / or calcium hydroxide, which are neutralizing agents containing Ba atoms and / or Ca atoms corresponding to the metal atom (A), can also be suitably used. The neutralization reaction may be carried out at a temperature below a predetermined temperature. This predetermined temperature is preferably 90°C or lower, more preferably 50°C or lower. This makes it easy to obtain a strontium zirconate-based powder with a small average primary particle size. The neutralization reaction may also be carried out at a temperature above the predetermined temperature. From the viewpoint of reaction rate, this predetermined temperature is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 25°C or higher. The pH after neutralization may be 6.8 to 8.5, 7.0 to 8.1, or 7.5 to 8.0.

[0035] After the neutralization reaction, the mixture is cooled to room temperature, and then the resulting salt is removed. For example, when zirconium oxychloride octahydrate is used as the zirconium salt, the salt produced by neutralization contains chlorine atoms (Cl atoms). It is preferable to remove the salt to sufficiently remove the Cl atoms, which would interfere with the reaction between zirconium hydroxide and the strontium compound in a later step.

[0036] The method for removing the salt produced by neutralization is not particularly limited. Since the zirconium hydroxide produced by neutralization is insoluble in water, while the salt is usually water-soluble, it is preferable to dissolve the salt in water and wash it away by washing. The removal method using water is also preferable from the viewpoint of ease of operation. The reaction product obtained by neutralization is a slurry containing zirconium hydroxide. The salt can be removed by, for example, generating a precipitate by centrifugation, separating the salt dissolved in the supernatant, and recovering the precipitate and washing it with water. From the viewpoint of thoroughly removing the salt, it is more preferable to separate and remove the supernatant after washing with water and repeat the same washing operation with water multiple times.

[0037] As described above, the slurry obtained by removing the salt produced by neutralization is subjected to the next step (2) as a zirconium atom-containing aqueous slurry. The zirconium atom (Zr atom) content in the zirconium atom-containing aqueous slurry is preferably 0.1 to 1.0 mol / kg, more preferably 0.2 to 0.9 mol / kg, and even more preferably 0.3 to 0.8 mol / kg, from the viewpoint of facilitating a uniform reaction with the strontium compound in step (2) and obtaining a fine zirconate strontium powder.

[0038] As the zirconium atom-containing aqueous slurry, a slurry obtained by adding powdered zirconium hydroxide to water without undergoing a neutralization reaction and salt removal operation, as in the slurry of (1a), may be used, i.e., the slurry shown in (1b). The slurry described in (1b) allows for the simple and low-cost preparation of a zirconium atom-containing aqueous slurry. However, the slurry prepared in (1a) is more likely to yield a finer strontium zirconate powder. Furthermore, when using zirconium hydroxide powder, it is preferable that the zirconium hydroxide particles in the prepared slurry are fine in order to obtain a fine strontium zirconate-based powder. From this viewpoint, the zirconium hydroxide powder has a BET specific surface area of ​​100 m². 2 It is preferable that it be 150m or more / g. 2 / g or more, more preferably 200m 2 It is 1 / g or more.

[0039] The process of preparing the zirconium atom-containing aqueous slurry is carried out at a temperature of 90°C or lower, preferably 50°C or lower, and more preferably at room temperature. This is because carrying out the process at a temperature of 90°C or lower prevents grain growth and allows for the production of fine particles. From the viewpoint of maintaining reactivity, a temperature of 5°C or higher is preferred.

[0040] (Process (2)) In step (2), an additive raw material containing a strontium compound is added to the zirconium atom-containing aqueous slurry obtained in step (1) to obtain a raw material mixture. That is, the raw material mixture is a mixture of the zirconium atom-containing aqueous slurry and the additive raw material.

[0041] From the viewpoint of obtaining a fine strontium zirconate-based powder, strontium carbonate (SrCO3), strontium hydroxide (Sr(OH)2), strontium oxide (SrO), and strontium peroxide (SrO2) are preferably used as the strontium compound in the aforementioned additive raw material, and strontium carbonate is more preferably used. These may be used individually or in combination of two or more. Furthermore, strontium chloride (CaCl2) is undesirable because residual chlorine may make it difficult to obtain fine strontium zirconate powder.

[0042] In order to obtain the strontium zirconate-based powder, the raw material mixture preferably contains 0.05 to 2.0 moles of Sr atoms per mole of Zr atoms, more preferably 0.2 to 1.5 moles, the total content of metal atoms (A) preferably 1.0 mole or less per mole of Sr atoms, and the total content of metal atoms (B) preferably 1.0 mole or less per mole of Zr atoms. In other words, it is preferable that the additive raw materials be added appropriately so that the content of Sr atoms, the total content of metal atoms (A), and the total content of metal atoms (B) in the raw material mixture are all within the range required to obtain the strontium zirconate-based powder. If the strontium zirconate powder to be manufactured is strontium zirconate (SrZrO3) powder, then the raw material mixture shall not contain metal atoms (A) and metal atoms (B).

[0043] If the strontium zirconate-based powder to be manufactured is the solid solution, a raw material mixture containing metal atoms (A) and / or metal atoms (B) is prepared using additive raw materials containing metal atoms (A) and / or metal atoms (B) in addition to the strontium compound. When producing the solid solution containing a metal atom (A), it is preferable to use an additive raw material containing a compound having a metal atom (A). Examples of compounds having a metal atom (A) include barium carbonate, barium hydroxide, calcium carbonate, and calcium hydroxide. When producing the solid solution containing metal atoms (B), it is preferable to use additive raw materials containing a compound having metal atoms (B). Examples of compounds having metal atoms (B) include titanium dioxide, hafnium oxide, and cerium oxide. When producing the solid solution containing both metal atom (A) and metal atom (B), additive raw materials containing a compound having metal atom (A) and a compound having metal atom (B) may be used.

[0044] In step (2) above, when obtaining the raw material mixture, an organic polymer-based dispersant may be added. Adding the organic polymer-based dispersant to the raw material mixture makes it easier to obtain a fine and uniform pulverized slurry in the wet grinding step (3) that follows.

[0045] The organic polymer-based dispersant can be any known dispersant used to improve the dispersibility of inorganic particles, particularly ceramics, in aqueous slurries. Preferably, the strontium zirconate-based powder is a dispersant obtained as a high-purity powder that contains as few metal impurities as possible. Examples of the organic polymer-based dispersants include polyoxyalkylene-based, polyacrylic acid-based, polycarboxylic acid-based, and polystyrene sulfonic acid-based polymer-based dispersants. Among these, polycarboxylic acid-based dispersants are preferably used.

[0046] The organic polymer dispersant should be added in an amount that is sufficient to improve the dispersibility of the pulverized slurry, from the viewpoint of the production efficiency of the strontium zirconate powder, etc. When the organic polymer dispersant is added, the amount added is preferably 10 parts by mass or less, more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of zirconium atoms.

[0047] (Step (3)) In step (3), the raw material mixture obtained in step (2) is wet-ground to obtain a ground slurry. After wet grinding the raw material mixture, it is calcined in the subsequent step (5), resulting in a BET specific surface area of ​​40.0 m². 2 It is possible to obtain fine calcined powder of 1g or more.

[0048] The raw material mixture to be crushed is an aqueous slurry with water as the dispersion medium. The aforementioned wet grinding method is not particularly limited, and general grinding methods such as ball mills and bead mills can be used. Specific grinding conditions can be appropriately set depending on the grinding equipment and the mixed components in the raw material mixture to be ground.

[0049] (Step (4)) In step (4), the pulverized slurry obtained in step (3) is dried at a temperature of 400°C or lower to obtain a dried powder. The drying process only needs to involve evaporating the water in the pulverized slurry, and the drying method is not particularly limited and can be carried out using known methods.

[0050] The drying may be done at room temperature, but from the viewpoint of manufacturing efficiency, heating is preferred. The drying temperature is preferably 50 to 300°C, more preferably 100 to 180°C, from the viewpoint of drying efficiency, maintaining the fineness of the dried powder, and ease of handling. From the same viewpoint, the drying time is preferably 6 to 60 hours, more preferably 10 to 50 hours, and even more preferably 12 to 48 hours. The drying atmosphere may be an atmospheric atmosphere.

[0051] (Step (5)) In step (5), the dried powder obtained in step (4) is calcined at a temperature of 600°C or higher but less than 800°C to obtain calcined powder. By firing the aforementioned dried powder at a temperature of 600°C to less than 800°C, a BET specific surface area of ​​40.0 to 100.0 m² is typically obtained. 2A fine calcined powder can be obtained at a density of / g.

[0052] The firing temperature is preferably 620 to 780°C, more preferably 650 to 750°C, from the viewpoint of manufacturing efficiency and maintaining the fineness and handling of the produced strontium zirconate-based powder. From a similar viewpoint, the drying time is preferably 0.2 to 10 hours, more preferably 0.5 to 8 hours, and even more preferably 1 to 5 hours. The firing atmosphere may be an atmospheric atmosphere.

[0053] (Process (6)) In step (6), the calcined powder obtained in step (5) is wet-milled using an organic dispersion medium and then dried to obtain a strontium zirconate powder. The calcined powder obtained in step (5) has excellent crushability, and can be made into an even finer powder by wet grinding using an organic dispersion medium. Therefore, the strontium zirconate powder obtained through step (6) has a BET specific surface area of ​​90 m². 2 / g or more, for example, 100m 2 It can be obtained as a fine powder exceeding / g.

[0054] Examples of organic dispersion media include methanol and ethanol, from the viewpoint of ease of handling and drying efficiency.

[0055] The aforementioned wet grinding method is not particularly limited, and general grinding methods such as ball mills and bead mills can be used. Specific grinding conditions can be appropriately set depending on the grinding equipment and the composition of the calcium zirconate powder to be ground. A finer powder can be obtained by using a bead mill than by using a ball mill.

[0056] The drying may be done at room temperature, but from the viewpoint of manufacturing efficiency, heating is preferred. The drying temperature is preferably 20 to 180°C, more preferably 30 to 150°C, and even more preferably 40 to 100°C, from the viewpoint of drying efficiency, maintaining the fineness of the dried powder, and ease of handling. From the same viewpoint, the drying time is preferably 1 to 48 hours, more preferably 2 to 36 hours, and even more preferably 3 to 24 hours. The drying atmosphere may be an atmospheric atmosphere.

[0057] [Molded products, sintered products] The molded article according to this embodiment is a molded article of the aforementioned strontium zirconate-based powder. The sintered product according to this embodiment is a sintered product of the strontium zirconate-based powder described above. The sintering temperature when obtaining a sintered product from the strontium zirconate-based powder is preferably 500 to 900°C, more preferably 600 to 800°C, and even more preferably 650 to 750°C. The sintering time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 4 hours, and even more preferably 1 to 3 hours. Sintering can be carried out, for example, in the atmosphere.

[0058] Strontium zirconate powder was produced by the method described in the following examples and comparative examples. Details of the raw materials and equipment (conditions) used are shown below. [Examples]

[0059] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0060] Strontium zirconate (hereinafter abbreviated as SZ) powder having a perovskite structure was produced by the method described in the Examples and Comparative Examples below. Details of the raw materials and equipment (conditions) used are shown below.

[0061] <Raw materials used> • Zirconium oxychloride octahydrate (ZrCl2O·8H2O): Manufactured by Kanto Chemical Co., Ltd. • Calcium hydroxide (Ca(OH)2): Manufactured by Kanto Chemical Co., Ltd. • Strontium carbonate (SrCO3): Manufactured by Kanto Chemical Co., Ltd. • Calcium carbonate (CaCO3): Manufactured by Shiraishi Calcium Co., Ltd. • Titanium dioxide (TiO2): "Super Titania (registered trademark) F-6", manufactured by Showa Denko Corporation. • Dispersant: "Kaocera (registered trademark) 2000", manufactured by Kao Corporation; polycarboxylic acid-based dispersant

[0062] <Device> • pH measurement (conductivity measurement) device: Portable pH meter "D-74", manufactured by Horiba, Ltd. • Centrifugal separator: "H-2000B", manufactured by Kokusan Co., Ltd.; centrifugal force 7000 × g, 3000 rpm, 5 minutes • Bead mill: "PicoMill (registered trademark) PCM-LR", manufactured by Asada Iron Works Co., Ltd.; Beads used: 0.3mm diameter yttrium-stabilized zirconia beads, rotation speed 40Hz, peripheral speed 8m / s • Electric furnace: Ultra-fast heating electric furnace "FUS622PB", manufactured by Advantec Toyo Co., Ltd.; heating rate 6°C / min, maximum temperature reached 700°C, holding time 2 hours.

[0063] (Example 1) 32.2 g (0.10 mol) of zirconium oxychloride octahydrate was placed in a 500 mL fluororesin beaker, 200.0 g of pure water was added, and the mixture was stirred to dissolve and prepare an aqueous solution. To the aforementioned aqueous solution, a suspension prepared by adding 7.4 g (0.10 mol) of calcium hydroxide to 200.0 g of pure water was added while stirring, and the mixture was stirred and mixed for 3 hours to neutralize (pH 7.6) (Step 1a). The temperature of the suspension was maintained between room temperature (25°C; the same applies below) and 50°C. The resulting reaction product was cooled to room temperature and then centrifuged to form a precipitate. The supernatant was replaced with pure water, stirred and mixed, and then centrifuged again. This process was repeated 10 times to wash away the salts from the reaction product. The salts were confirmed to have been sufficiently washed away by checking that the conductivity of the supernatant was less than 100 μS / cm, thereby obtaining a zirconium hydroxide (Zr(OH)4) slurry. To 200 g of the zirconium hydroxide (Zr(OH)4) slurry obtained as described above (aqueous slurry containing 0.10 moles of Zr atoms), strontium carbonate 14.32 (0.097 moles) and 5 g of dispersant were added. The resulting raw material mixture (Sr atoms / Zr atoms = 1 (molar ratio)) was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry was dried in a constant temperature oven at 100°C in an atmospheric environment for 48 hours to obtain a dried powder. The aforementioned dried powder was placed on an alumina firing dish and fired in an electric furnace at 700°C for 2 hours in an air atmosphere. After firing, it was allowed to cool naturally to below 200°C to obtain fired powder. The calcined powder was wet-milled in a bead mill using ethanol as a dispersion medium for 8 hours, and then allowed to stand and dry on a hot plate at 40°C for 24 hours to obtain SZ-based powder (SrZrO3).

[0064] (Example 2) 32.2 g (0.10 mol) of zirconium oxychloride octahydrate was placed in a 500 mL fluororesin beaker, 200.0 g of pure water was added, and the mixture was stirred to dissolve and prepare an aqueous solution. To the aforementioned aqueous solution, 10% by mass of ammonia water was added dropwise while stirring until the pH reached 8.0. The temperature of the suspension was maintained at room temperature (25°C) or higher and 50°C or lower. The resulting reaction product was cooled to room temperature and then centrifuged to form a precipitate. The supernatant was replaced with pure water, stirred and mixed, and then centrifuged again. This process was repeated 10 times to wash away the salts from the reaction product. The salts were confirmed to have been sufficiently washed away by checking that the conductivity of the supernatant was less than 100 μS / cm, thereby obtaining a zirconium hydroxide (Zr(OH)4) slurry. To this zirconium hydroxide slurry (aqueous slurry containing 0.10 moles of Zr atoms), 14.76 g (0.10 moles) of strontium carbonate and 5 g of dispersant were added. The resulting raw material mixture (Sr atoms / Zr atoms = 1 (molar ratio)) was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry was dried in a constant temperature oven at 100°C in an atmospheric environment for 48 hours to obtain a dried powder. The aforementioned dried powder was placed on an alumina firing dish and fired in an electric furnace at 700°C for 2 hours in an air atmosphere. After firing, it was allowed to cool naturally to below 200°C to obtain fired powder. The calcined powder was wet-milled in a bead mill using ethanol as a dispersion medium for 8 hours, and then allowed to stand and dry on a hot plate at 40°C for 24 hours to obtain SZ-based powder (SrZrO3).

[0065] (Example 3) A Zr atom-containing aqueous slurry was prepared in the same manner as in Example 1. To 180 g of this Zr atom-containing aqueous slurry (Zr atom content 0.09 mol), 4.00 g (0.04 mol) of calcium carbonate, 8.86 g (0.06 mol) of strontium carbonate, and 5 g of dispersant were added. The resulting raw material mixture was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry is then dried, calcined, wet-ground, and dried again in the same manner as in Example 1 to obtain SZ-based powder (Ca 0.4 Sr 0.6 We obtained ZrO3.

[0066] (Example 4) A Zr atom-containing aqueous slurry was prepared in the same manner as in Example 1. 180 g of this Zr atom-containing aqueous slurry (Zr atom content 0.09 mol) was mixed with 4.00 g (0.04 mol) of calcium carbonate, 8.86 g (0.06 mol) of strontium carbonate, 0.89 g (0.01 mol) of titanium dioxide, and 5 g of dispersant with pure water and stirred. The resulting raw material mixture was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry is then dried, calcined, wet-ground, and dried again in the same manner as in Example 1 to obtain SZ-based powder (Ca 0.4 Sr 0.6 Zr 0.9 Ti 0.1 O3) was obtained.

[0067] (Comparative Example 1) 32.2 g (0.10 mol) of zirconium oxychloride octahydrate was weighed into a 500 mL fluororesin beaker, 400 g of pure water was added, and the mixture was stirred to dissolve it. The top of the beaker was covered, a Liebig condenser was placed inside, and the liquid in the beaker was heated to 98°C using a mantle heater while stirring, and the mixture was heated under reflux in an atmospheric environment for 72 hours. Subsequently, the reaction product was neutralized with 25% by mass aqueous ammonia (pH 8.2), cooled to room temperature, and then centrifuged to form a precipitate. The supernatant was replaced with pure water, stirred and mixed, and then centrifuged again. This process was repeated 10 times to wash away the ammonia and chlorine components from the reaction product. The complete removal of ammonia and chlorine components was confirmed by the conductivity of the supernatant being less than 100 μS / cm. The obtained precipitate was dried in an 80°C constant temperature oven in an air atmosphere for 48 hours. The resulting dried material was crushed in a mortar and pestle, and the sieved powder was passed through a 200 μm mesh sieve to obtain zirconium oxide powder (Zr atom source; BET specific surface area 180 m²). 2 It was obtained as ( / g). To the Zr atom-containing aqueous slurry obtained by adding 10.0 g (0.081 mol) of the aforementioned zirconium oxide powder to 200 g of pure water, 11.81 g (0.08 mol) of strontium carbonate and 5 g of dispersant were added, and the resulting raw material mixture (Sr atom / Zr atom = 1 (molar ratio)) was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry was subjected to drying, calcination, wet grinding, and drying in the same manner as in Example 1 to obtain a powder containing SZ.

[0068] (Comparative Example 2) The powder obtained in Comparative Example 1 was heat-treated at 900°C for 2 hours to obtain heat-treated powder. The heat-treated powder was wet-milled in a bead mill using ethanol as a dispersion medium for 8 hours, and then allowed to stand and dry on a hot plate at 40°C for 24 hours to obtain SZ-based powder.

[0069] (Comparative Example 3) 32.2 g (0.10 mol) of zirconium oxychloride octahydrate was placed in a 500 mL fluororesin beaker, 200.0 g of pure water was added, and the mixture was stirred to dissolve and prepare an aqueous solution. To the aforementioned aqueous solution, a suspension prepared by adding 7.4 g (0.10 mol) of calcium hydroxide to 200.0 g of pure water was added while stirring, and the mixture was stirred and mixed for 3 hours to neutralize (pH 7.6) (Step 1a). The temperature of the suspension was maintained at 50°C or below. The resulting reaction product was cooled to room temperature and then centrifuged to form a precipitate. The supernatant was replaced with pure water, stirred and mixed, and then centrifuged again. This process was repeated 10 times to wash away the salts from the reaction product. The salts were confirmed to have been sufficiently washed away by checking that the conductivity of the supernatant was less than 100 μS / cm, thereby obtaining a zirconium hydroxide slurry. To the zirconium hydroxide (Zr(OH)4) slurry obtained above (aqueous slurry containing Zr atoms: Zr atom content 0.10 mol), 5.00 g (0.05 mol) of calcium carbonate, 7.38 g (0.05 mol) of strontium carbonate, and 5 g of dispersant were added. The resulting raw material mixture (Ca atom / Zr atom = 1 (molar ratio)) was wet-milled in a bead mill for 4 hours to obtain a pulverized slurry. The pulverized slurry was dried in a constant temperature oven at 100°C in an atmospheric environment for 48 hours to obtain a dried powder. The aforementioned dried powder was placed on an alumina firing dish and fired in an electric furnace at 700°C for 2 hours in an air atmosphere. After firing, it was allowed to cool naturally to below 200°C to obtain fired powder. The fired powder was wet-milled for 8 hours using ethanol as a dispersion medium in a bead mill, and then left to dry statically on a hot plate at 40 °C for 24 hours to obtain calcium zirconate-based powder.

[0070] [Analysis and measurement of powder] For each of the powders in the above Examples and Comparative Examples, analysis and measurement of the following items were performed. The measurement results are summarized in Table 1 below. In each of the following analysis and measurements, the powders obtained in the above Examples and Comparative Examples that had been crushed in a mortar were used as sample powders.

[0071] <Composition (element content)> For the sample powder, an XRF spectrum was measured with a multi-element simultaneous X-ray fluorescence analyzer "Simultix 14" (manufactured by Rigaku Corporation) to perform a composition analysis of the SZ-based powder and confirm the constituent atomic composition.

[0072] <BET specific surface area> In accordance with JIS R 1626:1996, the BET specific surface area was measured by the BET three-point method using nitrogen gas as an adsorbate with a fully automatic BET specific surface area measuring device ("Macsorb (registered trademark) HM model-1208", manufactured by Mountech Co., Ltd.).

[0073] <Average primary particle size> The average primary particle size of the sample powder was determined by TEM observation. For TEM observation, the sample powder was dispersed in an ethanol solution, and the recovered product with a microgrid mesh was used as a TEM observation sample. Observation was performed at a magnification of 100,000 times using an electrolytic emission transmission electron microscope ("HF-2200", manufactured by Hitachi High-Technologies Corporation; acceleration voltage 200 kV) and a CCD camera ("Orius SC600", manufactured by Gatan). In the observed images, the major and minor axes of 20 arbitrary particles were measured, and their arithmetic mean was defined as the particle diameter. The major axis is the length (maximum length) when any two points on the contour line of a single particle shape are selected such that the distance between them is maximized. The minor axis is the length (minimum length) when any two points on the contour line of a single particle shape are selected such that the distance between them is minimized. From the 20 particle size data points, the 5 data points with the largest values ​​and the 5 data points with the smallest values ​​were removed, and the arithmetic mean of the remaining 10 data points was calculated. This value was defined as the average primary particle size.

[0074] <Powder X-ray diffraction measurement (perovskite structure)> X-ray diffraction measurements were performed using an X-ray diffractometer ("X'pert PRO", manufactured by Panalytical). The measurements were performed under the following conditions: copper target, CuKα radiation (Cu-Kα1), tube voltage 45kV, tube current 40mA, measurement range 2θ = 18°~80°, sampling width 0.0167°, and scanning speed 3.3° / min. The powder XRD charts for the examples and comparative examples are shown in Figures 1 to 7. Figures 1 to 4 are the powder XRD charts for the heat-treated powders of Examples 1 to 4, respectively, and Figures 5 to 7 are the powder XRD charts for the heat-treated powders of Comparative Examples 1 to 3, respectively.

[0075] <Dielectric constant> Using the powders obtained in the examples and comparative examples, pellets were formed using a hydraulic press with an inner diameter of 30 mm in a tablet molder, applying a pressure of 100 MPa. The thickness of the molded product was measured with a micrometer, and the volume of the molded product was calculated. The mass of the molded product was also measured, and the compaction density was calculated. Using these pellets, the dielectric constant at 1 MHz was measured using a dielectric measurement electrode (Keysight 16451B) and a precision LCR meter (Agilent Technologies 4284A).

[0076] <Shrinkage rate> 2.50 g of the powder obtained in the examples and comparative examples was weighed, placed in a Φ30 mm circular mold, and compressed at 10 MPa to form the product. The product was then heated in an oven at a heating rate of 5°C / min until it reached a thermocouple reading of 1150°C. After maintaining the temperature for 2 hours, the heater was turned off, and the product was removed after 12 hours to obtain a sintered product. The shrinkage rate was measured by taking the average of two perpendicular diameters (A mm) and calculating the value from (A / 30)-1. The temperature indicated by a Refatherm (JFCC Practical Standard Material Series TYPE L1) placed simultaneously was 1147°C.

[0077] [Table 1]

[0078] As shown in Table 1, according to the embodiment of the present invention, the BET specific surface area is 90.0 m². 2 It was confirmed that fine SZ-based powders of 1 / g or more could be obtained. Furthermore, Figures 1-4 confirmed that the crystal structure of Examples 1-4 was all perovskite. These powders showed high dielectric constants of 46 or higher and large shrinkage rates of 5.8% or higher at 1150°C. A large shrinkage rate indicates that dense films can be made at low temperatures, making it possible to manufacture ceramic capacitors at lower temperatures than conventional methods. Therefore, the zirconate compounds obtained in these examples can be said to be suitable materials for dielectrics where thin films are required. On the other hand, when the slurry was prepared by heating to 98°C during the slurry preparation process (Comparative Example 1, Figure 5), SZ was not sufficiently generated at the same reaction temperature as the example (700°C). Furthermore, the BET specific surface area was also low. When high-temperature treatment (900°C) was applied (Comparative Example 2, Figure 6), although the SZ generation reaction progressed, the BET specific surface area decreased, and even after wet grinding, the BET specific surface area was 100.0 m². 2 Fine SZ-based powders with a particle size greater than / g could not be obtained. This is thought to be because the high-temperature treatment caused the powder particles to condense more firmly, making them difficult to break down. Furthermore, the compound obtained in Comparative Example 3 has a strontium content of 50 at% or less at the A site, which suggests that both its dielectric constant and shrinkage rate are inferior.

Claims

1. BET specific surface area 90.0m 2 / g or more 120.0m 2 A strontium zirconate-based powder containing more than 50 at% strontium atoms at the A site of the perovskite structure, with a concentration of less than / g.

2. The strontium zirconate-based powder according to claim 1, wherein the average primary particle size is 5.0 to 50.0 nm.

3. The BET specific surface area is 90.0 m² / g or more and 200.0 m² / g or less, and the A site of the perovskite structure contains more than 50 at% strontium atoms. A strontium zirconate-based powder with an average primary particle size of 5.0 to 50.0 nm.

4. A strontium zirconate-based powder according to any one of claims 1 to 3, comprising a solid solution containing one or more metal atoms (A) selected from barium atoms and calcium atoms, wherein the total content of the metal atoms (A) is less than 1.0 mole per mole of strontium atoms.

5. The BET specific surface area is 90.0 m² / g or more and 200.0 m² / g or less, and the A site of the perovskite structure contains more than 50 at% strontium atoms. A strontium zirconate-based powder comprising a solid solution containing one or more metal atoms (A) selected from barium atoms and calcium atoms, wherein the total content of the metal atoms (A) is less than 1.0 mole per mole of strontium atoms.

6. A strontium zirconate-based powder according to any one of claims 1 to 5, comprising a solid solution containing one or more metal atoms (B) selected from titanium atoms, hafnium atoms, and cerium atoms, wherein the total content of the metal atoms (B) is less than 1.0 mole per mole of zirconium atoms.

7. The BET specific surface area is 90.0 m² / g or more and 200.0 m² / g or less, and the A site of the perovskite structure contains more than 50 at% strontium atoms. A strontium zirconate-based powder comprising a solid solution containing one or more metal atoms (B) selected from titanium atoms, hafnium atoms, and cerium atoms, wherein the total content of the metal atoms (B) is less than 1.0 mole per mole of zirconium atoms.

8. A strontium zirconate-based powder according to claims 1 to 7, used as a material for ceramic capacitors.

9. A method for producing strontium zirconate-based powder, (1) A step of preparing a zirconium atom-containing aqueous slurry at a temperature of 90°C or below, Step (2) involves adding an additive raw material containing a strontium compound to the aforementioned zirconium atom-containing aqueous slurry to obtain a raw material mixture. (3) A step of wet grinding the raw material mixture to obtain a ground slurry, The process (4) involves drying the pulverized slurry at a temperature of 400°C or lower to obtain a dried powder, The process (5) involves firing the aforementioned dried powder at a temperature of 600°C or higher but less than 800°C to obtain fired powder, A method for producing strontium zirconate powder, comprising the steps (6) of wet grinding the calcined powder using an organic dispersion medium and then drying it to obtain strontium zirconate powder.

10. The aforementioned zirconium atom-containing aqueous slurry is one or more selected from (1a) and (1b) below. (1a) A slurry obtained by neutralizing an aqueous zirconium salt solution and removing the resulting salt. (1b) Slurry obtained by adding zirconium hydroxide to water The strontium compound is one or more selected from strontium carbonate, strontium hydroxide, strontium oxide, and strontium peroxide. The method for producing strontium zirconate powder according to claim 9, wherein the raw material mixture contains 0.05 to 2.0 moles of strontium atoms per mole of zirconium atoms, the total content of one or more metal atoms (A) selected from barium atoms and calcium atoms is 1.0 mole or less per mole of strontium atoms, and the total content of one or more metal atoms (B) selected from titanium atoms, hafnium atoms and cerium atoms is 1.0 mole or less per mole of zirconium atoms.

11. A method for producing strontium zirconate powder according to claim 10, wherein the additive raw material added in step (2) includes a compound having the metal atom (A).

12. A method for producing strontium zirconate powder according to claim 10 or 11, wherein the additive raw material added in step (2) includes a compound having the metal atom (B).

13. A method for producing strontium zirconate powder according to any one of claims 10 to 12, wherein the neutralizing agent used for neutralizing the zirconium salt aqueous solution in (1a) is one or more selected from calcium hydroxide, barium hydroxide, strontium hydroxide, and ammonia.

14. A method for producing strontium zirconate powder according to any one of claims 10 to 13, wherein the zirconium salt in (1a) is one or more selected from zirconium oxychloride octahydrate and zirconium nitrate dihydrate.

15. A method for producing strontium zirconate powder according to any one of claims 9 to 14, wherein in step (2) above, an organic polymer-based dispersant is further added to obtain the raw material mixture.

16. A sintered product of strontium zirconate powder according to any one of claims 1 to 8.

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