Zirconate compound powder

Abstract

This invention provides a zirconate compound powder that allows for the production of sintered bodies with a high shrinkage rate at a low sintering temperature, even without containing impurities. [Solution] The material has a perovskite structure ABO3, with at least one atom selected from the group consisting of barium, strontium, and calcium in the A site, and zirconium in the B site, and a BET specific surface area of ​​20 m². 2 A zirconate compound (A) having less than / g, and a perovskite structure ABO3 having at least one atom selected from the group consisting of barium, strontium, and calcium at the A site, and zirconium at the B site, with a BET specific surface area of ​​20m². 2 A zirconate compound powder containing zirconate compound (B) in an amount of 1 / g or more, wherein the content ratio of zirconate compound (B) in 100 ml of the total amount of zirconate compound (A) and zirconate compound (B) {B / (A+B)} is 0.1 to 50 mol%.

Description

Technical Field

[0001] The present invention relates to zirconic acid compound powder and a method for producing the same.

Background Art

[0002] A multilayer ceramic capacitor (MLCC) is an electronic material mainly composed of an electrode layer containing an active material and an ion conductive material, and a dielectric layer mainly containing an ion conductive material, and is roughly classified into a high dielectric constant type and a temperature compensation type according to temperature characteristics. These two types have different ion conductive materials. The high dielectric constant type often uses a barium titanate-based compound, and the temperature compensation type often uses a calcium zirconate-based compound.

[0003] Both the electrode layer and the dielectric layer are formed into a sheet shape, laminated, and then sintered. This sintering temperature is generally 1000 °C or higher. However, as the temperature becomes higher, the conductor material for wiring that can be used is limited, and a high-temperature sintering furnace or an ultra-high-temperature sintering furnace is required, so the equipment cost becomes high, and the energy cost inevitably becomes high, resulting in a high product price.

[0004] Therefore, an additive of a sintering aid for lowering the sintering temperature of the solid electrolyte material has been added, and a new sintering aid has been studied. [[ID=2②]]

[0005] As conventional sintering aids, for example, those obtained by adding a low-melting glass to an alumina (Al2O3)-based base material (see, for example, Patent Document 1), those obtained by adding a glass and CuO to a base material composed of oxides of Ca, Nb, and Ti (see, for example, Patent Document 2), a ceramic dielectric containing a sintering aid composed of at least one of manganese and magnesium, silicon, and boron (Patent Document 3), etc. are disclosed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, these conventional methods did not sufficiently reduce the sintering temperature in relation to the addition of the sintering aid per unit weight to the main component, nor did they yield satisfactory sintering shrinkage rates. Furthermore, increasing the amount of sintering aid added to lower the sintering temperature resulted in the inclusion of many foreign substances, leading to a greater degree of deterioration in the properties of the base material itself.

[0008] Therefore, the present invention aims to provide a zirconate compound powder that can produce a sintered body with a high shrinkage rate at a low sintering temperature, even without containing impurities. [Means for solving the problem]

[0009] The present invention provides the following means. [1] Having a perovskite structure ABO3, the A site contains at least one atom selected from the group consisting of barium, strontium, and calcium, and the B site contains zirconium, with a BET specific surface area of ​​20 m². 2 Zirconate compounds (A) that are less than / g, and It has a perovskite structure ABO3, with at least one atom selected from the group consisting of barium, strontium, and calcium in the A site, and zirconium in the B site, and a BET specific surface area of ​​20 m². 2 Zirconate compounds (B) that are 1 / g or more Includes, A zirconate compound powder in which the content ratio {B / (A+B)} of zirconate compound (B) in a total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%. [2] The zirconate compound powder described in [1] above, wherein the cumulative value of pore volumes in the range of pore diameters from 1.5 to 50.5 nm in the pore distribution curve is 0.01 ml / g or more and 0.27 ml / g or less. [3] A solid electrolyte sintered body obtained by sintering the zirconate compound powder described in [1] or [2] above. [4] Having a perovskite structure ABO3, the A site contains at least one atom selected from the group consisting of barium, strontium, and calcium, and the B site contains zirconium, with a BET specific surface area of ​​20 m². 2 A zirconate compound (A) having a density of less than 1 / g, and a perovskite structure ABO3 having at least one atom selected from the group consisting of barium, strontium, and calcium at the A site, and zirconium at the B site, with a BET specific surface area of ​​20 m². 2 A method for producing zirconate compound powder, comprising a mixing step (7) of mixing zirconate compound (B) in a quantity of 1 / g or more with zirconate compound (A) in a ratio such that the content ratio of zirconate compound (B) {B / (A+B)} in 100 ml of the total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%. [5] A method for producing zirconate compound powder according to [4] above, comprising, before step (7), a step (4) of mixing at least one compound selected from a barium-containing compound, a strontium-containing compound, and a calcium-containing compound with a zirconium-containing compound to obtain a raw material mixture, and a step (6) of calcining the raw material mixture at 700°C or higher to obtain zirconate compound (A) and zirconate compound (B). [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a zirconate compound powder that can produce a sintered body with a high shrinkage rate at a low sintering temperature, even without containing impurities. [Modes for carrying out the invention]

[0011] The zirconate compound powder of the present invention will be described in detail below. The definitions and meanings of terms and notations used in this specification are given below. The notation "X~Y" (where X and Y are numerical values) refers to a numerical range with X as the lower limit and Y as the upper limit. For numerical ranges (for example, ranges of content, etc.), the lower and upper limits described in stages may be combined independently. The lower and upper limits of the numerical range may be replaced with the numerical values ​​described in the examples. In this specification, the property of zirconate compound powders that allows for the production of sintered bodies with a high shrinkage rate at a low sintering temperature may be referred to as "excellent sinterability." A "zirconate compound" refers to a complex oxide having a perovskite structure ABO3, containing at least one atom selected from barium, strontium, and calcium at the A site, and containing zirconium at the B site.

[0012] [Zirconate compound powder] The zirconate compound powder in one embodiment of the present invention has a perovskite structure ABO3, containing at least one atom selected from the group consisting of barium, strontium, and calcium at the A site, and containing zirconium at the B site, with a BET specific surface area of ​​20 m². 2 Zirconate compounds (A) that are less than / g, and It has a perovskite structure ABO3, with at least one atom selected from the group consisting of barium, strontium, and calcium in the A site, and zirconium in the B site, and a BET specific surface area of ​​20 m². 2 Zirconate compounds (B) that are 1 / g or more Includes, This is a zirconate compound powder in which the content ratio {B / (A+B)} of zirconate compound (B) in a total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%. Zirconate compound powders that meet the above requirements exhibit excellent sinterability and can be suitably used as raw materials in various applications such as ceramic capacitors, piezoelectric elements, abrasives, and catalysts, taking advantage of these properties. In particular, they are suitable as raw materials for dielectric materials where thin films are required, i.e., as raw materials for ceramic capacitors.

[0013] (Zirconate compound (A) and zirconate compound (B)) The zirconate compound (A) and the zirconate compound (B) have a perovskite structure ABO3, with at least one atom selected from the group consisting of calcium, barium, and strontium at the A site, and zirconium at the B site. Here, the B site refers to the 12-coordinate portion in the perovskite structure, and the A site refers to the 6-coordinate portion in 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.

[0014] Calcium, strontium, and barium are all Group 2 atoms and, in particular, share similarities in chemical reactions as alkaline earth metals. When these atoms are used in dielectric materials, their dielectric constant and electrical properties are improved, and their temperature stability is enhanced.

[0015] The content of atoms contained in the A site of the zirconate compound (zirconate compound (A) and zirconate compound (B)) is preferably 0.05 to 2.0 moles per mole of zirconium (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 zirconate compound.

[0016] Site B may further contain, for example, Ti or Hf. Including Ti or Hf has the effect of improving high dielectric constant properties, improving temperature stability, improving mechanical properties, reducing electrical losses, adjusting phase transition properties, and improving changes in dielectric properties due to external electrodes. The zirconate compound powder may be, for example, barium calcium zirconate.

[0017] From the viewpoint of increasing the dielectric constant, the total content of calcium, barium, and strontium in 100 mol% of atoms contained in the A site of the perovskite structure is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 75 to 100 mol%, and even more preferably 80 to 100 mol%. From the viewpoint of increasing the dielectric constant, the proportion of zirconium atoms (Zr) in 100 mol% of atoms contained in the B site of the perovskite structure is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 75 to 100 mol%, and even more preferably 80 to 100 mol%.

[0018] In this invention, zirconium may contain hafnium atoms (Hf) as unavoidable impurities that are difficult to separate and originate from the raw materials of the zirconium-containing compound. This is based on the fact that zirconium and hafnium have similar chemical properties and are very difficult to separate industrially, and therefore, in the raw materials of the zirconate compound powder used in this invention, the zirconium content is generally expressed as a value that includes the unavoidable impurity Hf (usually about 2% by mass relative to 98% by mass of zirconium). The content of each constituent atom in the zirconate compound powder can be measured by X-ray fluorescence (XRF) analysis. Specifically, it can be determined by the method described in the examples.

[0019] (Content) In one embodiment of the present invention, the zirconate compound powder is a zirconate compound powder in which the content ratio {B / (A+B)} of zirconate compound (B) in a total amount of zirconate compound (A) and zirconate compound (B) of 100 ml is 0.1 to 50 mol%. When the content ratio {B / (A+B)} is 0.1 mol% or more, the shrinkage rate when creating a sintered body increases, and sintering proceeds more easily. This is presumed to be due to improved packing and improved adhesion due to the small particle size of the zirconate compound (B) (large BET specific surface area). From a similar viewpoint, the content ratio {B / (A+B)} is preferably 1 mol% or more, and more preferably 3 mol% or more. When it is 50 mol% or less, the powder physical properties such as specific surface area do not change significantly, and the impact on the physical properties and handling of the powder is small. From a similar viewpoint, it is preferably 10 mol% or less, and more preferably 5 mol% or less. The content ratio {B / (A+B)} is preferably 0.1 to 50 mol%, more preferably 1 to 10 mol%, and even more preferably 3 to 5 mol%.

[0020] The zirconate compound powder according to this embodiment may contain other components in addition to zirconate compound (A) and zirconate compound (B), as long as they do not hinder the effects of the present invention, but it is preferable that they are not included. The total content of zirconate compound (A) and zirconate compound (B) in 100 mol% of the total amount of zirconate compound powder is preferably 80-100 mol%, preferably 90-100 mol%, more preferably 95-100 mol%, even more preferably 98-100 mol%, even more preferably 99-100 mol%, and may be 100 mol%, based on metal atoms (including metalloid atoms (boron, silicon, germanium, arsenic, antimony, and tellurium)). The total content of zirconate compound (A) and zirconate compound (B) in 100% by mass of the total amount of zirconate compound powder is preferably 80-100% by mass, preferably 90-100% by mass, preferably 95-100% by mass, more preferably 98-100% by mass, even more preferably 99-100% by mass, and may be 100% by mass.

[0021] (BET specific surface area) In one embodiment of the present invention, the zirconate compound powder has a BET specific surface area of less than 20 m 2 / g for the zirconate compound (A). When it is less than 20 m 2 / g, the balance between the dielectric constant and the high-temperature stability when used in the dielectric phase of a ceramic capacitor is good, and the durability also tends to be good. From the same perspective, more preferably, it is 18 m 2 / g or less, still more preferably 17 m 2 / g or less. When the BET specific surface area of the zirconate compound (A) is 1 m 2 / g or more, it is suitable for miniaturization of ceramic capacitors. From the same perspective, more preferably, it is 5 m 2 / g or more, still more preferably 10 m 2 / g or more, even more preferably 15 m 2 / g or more. From this perspective, the BET specific surface area of the zirconate compound (A) is preferably 1 m 2 / g or more and less than 20 m 2 / g, more preferably 5 to 18 m 2 / g, still more preferably 10 to 17 m 2 / g, even more preferably 15 to 17 m 2 / g.

[0022] The zirconate compound (B) has a BET specific surface area of 20 m 2 / g or more. When it is in this range, it effectively acts as an aid for reducing the sintering temperature. From the same perspective, preferably, it is 22 m 2 / g or more, more preferably 25 m 2 / g or more. The BET specific surface area is preferably 400 m 2 / g or less. When it is in this range, the deterioration of handling properties can be suppressed, and it becomes easier to maintain the dielectric constant and durability of the dielectric layer. From the same perspective, more preferably, it is 40 m 2 / g or less, still more preferably 30 m 2 / g or less. From this viewpoint, the BET specific surface area of ​​the zirconate compound (B) is preferably 20 to 400 m². 2 / g, more preferably 22-40m 2 / g, more preferably 25-30m 2 It is / g.

[0023] One embodiment of the present invention aims to provide a zirconate compound powder that has a small specific surface area and can produce a sintered body with a high shrinkage rate at a low sintering temperature even without containing impurities. In the zirconate compound powder according to this embodiment, the content ratio of zirconate compound (B) {B / (A+B)} in the total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%, and therefore the BET specific surface area is 20 m². 2 Because the zirconate compound (A), which has a content of less than 50 / g, has a high content of 50-99.9 mol%, the specific surface area of ​​the zirconate compound powder is small. As a result, when used as the dielectric phase of a ceramic capacitor, it has a good balance between dielectric constant and high-temperature stability, and tends to have good durability. Furthermore, the zirconate compound powder according to this embodiment has a BET specific surface area of ​​20 m². 2 Because it contains zirconate compound (B) in a specific proportion of 1 / g or more, it effectively acts as an aid to lower the sintering temperature, and therefore a sintered body can be obtained at a low sintering temperature with a high shrinkage rate even without impurities. From this viewpoint, the BET specific surface area of ​​the zirconate compound powder is preferably 1.0 to 25.0 m². 2 / g, more preferably 5.0~25.0m 2 / g, more preferably 10.0 to 25.0m 2 / g, more preferably 15.0-25.0m 2 / g, more preferably 16.3-25.0m 2 / g, more preferably 16.4~22.0m 2 / g, more preferably 16.4-21.0m 2 It is / g.

[0024] 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 examples below. This BET specific surface area is an indicator of the fineness of the zirconate compound powder, and the larger the value of this BET specific surface area, the finer the zirconate compound powder is considered to be.

[0025] (pore volume) In one embodiment of the present invention, the integrated value of the differential pore volume in the pore diameter range of 1.5 to 50.5 nm in the pore distribution curve of the zirconate compound powder is preferably 0.01 ml / g or more, more preferably 0.05 ml / g or more, and even more preferably 0.09 ml / g or more. Within this range, there is a certain amount of pores, which improves the density and uniformity after firing during the firing process of the multilayer ceramic capacitor, suppresses changes in dielectric properties, and improves the stability of the material. The integrated value of the differential pore volume in the pore diameter range of 1.5 to 50.5 nm in the pore distribution curve is preferably 0.27 ml / g or less, more preferably 0.16 ml / g or less, and even more preferably 0.10 ml / g or less. Within this range, the viscosity does not increase excessively when dispersed in the dispersion medium, making it easy to handle during reactions and slurry preparation using zirconate compound powder, and resulting in high production efficiency. From this viewpoint, the integrated value of the differential pore volume in the pore diameter range of 1.5 to 50.5 nm in the pore distribution curve of the zirconate compound powder is preferably 0.01 to 0.27 ml / g, more preferably 0.05 to 0.16 ml / g, even more preferably 0.09 to 0.16 ml / g, and even more preferably 0.09 to 0.10 ml / g. Pore ​​volume can be measured by the method described in the examples.

[0026] [Solid electrolyte sintered body] The solid electrolyte sintered body in one embodiment of the present invention is obtained by sintering the zirconate compound powder. The solid electrolyte sintered body can be suitably manufactured by pressurizing and molding the zirconate compound powder and then heating it.

[0027] (Application) The aforementioned zirconate compound powder can be suitably used as a raw material for dielectric materials, oxygen sensor materials, and zirconia-based ceramics. Furthermore, a solid electrolyte sintered body obtained by mixing the zirconate compound powder with other materials as appropriate and sintering it can be suitably used as a dielectric material.

[0028] [Method for producing zirconate compound powder] The method for producing the zirconate compound powder of the present invention is not limited, but preferably includes the following step (7), more preferably includes steps (4), (6), and (7), and even more preferably includes steps (1), (2), (4) to (8).

[0029] Step (1) is a step in which a zirconium hydroxide slurry is obtained by neutralizing a zirconium salt with an alkaline solution. Step (2) is a step of washing the zirconium hydroxide slurry. Step (3) is the process of maintaining the zirconium hydroxide slurry at 60 to 130°C. Step (4) is a step in which a raw material mixture is obtained by mixing a zirconium-containing compound with a metal compound. Step (5) is the process of drying the raw material mixture. Step (6) is a step of firing the raw material mixture at 700°C or higher to obtain zirconate compound (A) and zirconate compound (B). Step (7) is a step in which zirconate compound (A) and zirconate compound (B) are mixed in such a ratio that the content ratio of zirconate compound (B) {B / (A+B)} in a total amount of 100 ml of zirconate compound (A) is 0.1 to 50 mol%. Step (8) is the step of drying the zirconate compound.

[0030] <Process (1)> Step (1) is a step in which the zirconium salt is neutralized to obtain a zirconium hydroxide slurry. In step (1), it is preferable to neutralize an aqueous zirconium salt solution containing water as a dispersion medium with an alkaline solution to obtain a zirconium hydroxide slurry. Examples of the aforementioned zirconium salts include zirconium oxychloride octahydrate, zirconium nitrate dihydrate, zirconium sulfate tetrahydrate, and zirconium oxyacetate. These may be used individually or in combination of two or more. Of these, zirconium oxychloride octahydrate and zirconium nitrate dihydrate are preferred, with zirconium oxychloride octahydrate being more preferred. This is because it is commonly used as a raw material for zirconia compounds and is favorable in terms of price and supply.

[0031] In the present invention, the water content in the total amount of dispersion medium in the slurry is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

[0032] Neutralization is preferably carried out on the alkaline side with a pH greater than 7.0, more preferably in the pH range of 7.5 to 9.0, and even more preferably in the pH range of 7.5 to 8.5. Specifically, by dropwise mixing an acidic aqueous solution of the zirconium salt into a sufficient amount of alkaline solution and carrying out the reaction while maintaining the pH on the alkaline side, fine zirconium hydroxide with a large specific surface area can be obtained. When the neutralization reaction is carried out on the alkaline side, 300m 2 It is easy to obtain zirconium hydroxide in quantities of / g or more.

[0033] Examples of alkaline solutions used in the neutralization reaction include aqueous ammonia and aqueous solutions of various hydroxides. These may be used individually or in combination of two or more. From an environmental and contamination standpoint, the hydroxide is preferably a hydroxide of a metal atom (A) constituting the A site or a metal atom (B) constituting the B site of the target product. Specifically, calcium hydroxide, barium hydroxide, and strontium hydroxide are more preferred. The neutralization reaction can be carried out in air at room temperature, but it is preferable to carry it out at a low temperature because it requires less alkaline agent for precipitation. The temperature of the reaction atmosphere is preferably 10 to 60°C, more preferably 15 to 55°C, and even more preferably 25 to 50°C.

[0034] The concentration of the zirconium salt in the aqueous solution of the zirconium salt is preferably 0.1 to 5 mol / L, more preferably 0.3 to 2 mol / L, and even more preferably 0.4 to 1.5 mol / L. A concentration of 0.1 mol or more results in high reaction efficiency, while a concentration of 5 mol or less results in high reaction uniformity.

[0035] <Process (2)> Step (2) is a step to wash the zirconium hydroxide slurry obtained in step (1), and is performed with the aim of washing away chlorine and nitric acid contained in the zirconium salt raw material. Specifically, washing can be performed by decantation, which involves adding a large amount of water to the zirconium hydroxide slurry, stirring, and then discarding the supernatant. Alternatively, the zirconium slurry can be centrifuged using a centrifuge to form a precipitate, discarding the supernatant, adding pure water, stirring and mixing, and then centrifuging again. Other methods, such as ultrafiltration and filter pressing, can also be used, provided that the microstructure of the zirconium hydroxide is not destroyed. The cleaning is preferably carried out in the atmosphere at room temperature. The temperature during cleaning is preferably 10 to 40°C, more preferably 15 to 30°C, and even more preferably 15 to 25°C.

[0036] <Process (3)> Step (3) is a step of maintaining the zirconium hydroxide slurry obtained in step (1) or (2) at 60 to 130°C. Including this step increases the BET specific surface area to 300 m². 2 This allows us to obtain zirconium hydroxide with a concentration of 1 / g or more. This enhances the reactivity in step (4). From the viewpoint of increasing the fineness of the slurry, the holding temperature is preferably 60 to 130°C, more preferably 60 to 120°C, even more preferably 70 to 100°C, even more preferably 75 to 90°C, and most preferably 75 to 85°C. For example, if the zirconium hydroxide slurry obtained in step (2) is kept warm at 80°C for 12 hours and then dried at 120°C for 24 hours, the BET specific surface area will be 400 m². 2 It becomes possible to obtain a fine structure of approximately / g. On the other hand, if dried in the same way at 120°C without heating, 300-350m 2 This results in zirconium hydroxide per gram.

[0037] The heat retention time is preferably 1 hour or more, more preferably 5 to 96 hours, even more preferably 10 to 48 hours, and even more preferably 10 to 24 hours, from the viewpoint of improving the fineness of the slurry and shortening the manufacturing time.

[0038] <Process (4)> Step (4) is a step of mixing a zirconium-containing compound with a metal compound to obtain a raw material mixture. The zirconium-containing compound is preferably a slurry containing zirconium hydroxide because it has high reactivity, and more preferably a slurry containing zirconium hydroxide and water. It is preferable to use zirconium hydroxide produced by step (2) or (3) above.

[0039] The metal compound is a metal compound containing metal atoms other than zirconium (Zr) atoms, and is preferably a metal compound containing at least one metal atom (A) selected from the group consisting of barium, strontium, and calcium. Specific examples of metal compounds include metal hydroxides such as calcium hydroxide, barium hydroxide, and strontium hydroxide, and metal carbonates such as calcium carbonate, barium carbonate, and strontium carbonate. From a cost perspective, calcium hydroxide, barium hydroxide, calcium carbonate, and barium carbonate are preferred. The metal compound containing metal atom (A) may be one type or multiple types.

[0040] Furthermore, a compound containing a metal atom (B) may be added, and one or more compounds selected from oxides and peroxides containing a metal atom (A) may also be added. The compound containing a metal atom (B) is a compound containing at least one of titanium (Ti) atoms, hafnium (Hf) atoms, or cerium (Ce) atoms. It may be an oxide, specifically titanium oxide, hafnium oxide, cerium oxide, etc., and titanium oxide is preferred.

[0041] For every 1 mole of zirconium atoms and metal atoms (B) in the aforementioned zirconium hydroxide, 0.80 moles or more and less than 1.20 moles of metal atoms (A) may be added, or 0.85 moles or more and less than 1.15 moles may be added. The proportion of zirconium atoms (Zr) in 100 mol% of the atoms constituting the B site is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, even more preferably 75 to 100 mol%, and even more preferably 80 to 100 mol%.

[0042] Step (4) can be carried out at room temperature in an atmospheric environment. The temperature during mixing is preferably 10 to 40°C, more preferably 15 to 30°C, and even more preferably 15 to 25°C. Mixing can be done using a ball mill, bead mill, etc., or by stirring with a stirring blade in a container. The mixing and stirring time in step (4) is preferably 1 to 36 hours, more preferably 2 to 24 hours, and even more preferably 3 to 20 hours.

[0043] (Step (5)) The method for producing zirconate compound powder may include a step (5) in which the raw material mixture obtained in step (4) is dried. This allows the liquid to evaporate and a high-purity zirconate compound powder to be obtained. Drying methods include, but are not limited to, hot air drying, heating drying using a hot plate, vacuum drying, and natural drying. Drying atmospheres include, but are not limited to, drying under an inert gas atmosphere or drying under atmospheric conditions.

[0044] The drying temperature is 400°C or lower, preferably 300°C or lower, more preferably 200°C or lower, even more preferably 160°C or lower, and even more preferably 150°C or lower. Drying at 400°C or lower allows for the maintenance of a high specific surface area. Drying at higher temperatures, such as heat treatment (calcination) above 400°C, promotes aggregation of the resulting zirconate compound and reduces its fineness. From the viewpoint of evaporating the liquid, a temperature of 0°C or higher is preferred, and 20°C or higher is more preferred. The drying time is preferably 1 to 96 hours, more preferably 12 to 72 hours, and even more preferably 20 to 48 hours.

[0045] <Process (6)> Step (6) is a step of calcining the raw material mixture obtained in step (4) or step (5) to obtain zirconate compound (A) and zirconate compound (B). From the viewpoint of forming a perovskite structure, a firing temperature of 700°C or higher is preferable. From the same viewpoint, 800°C or higher is more preferable, and 950°C or higher is even more preferable. By firing at 1200°C or lower, aggregation is less likely to occur and the specific surface area can be maintained. The BET specific surface area of ​​the zirconate compound can be controlled by the firing temperature, and at temperatures above 1010°C, the BET specific surface area can be increased to 20 m². 2 It is easy to reduce the BET specific surface area to less than 20 m² at temperatures below 1000°C. 2 It's easy to make it more than / g. The firing time is preferably 1 to 54 hours, more preferably 1 to 48 hours, and even more preferably 1 to 16 hours. The firing atmosphere may be an atmospheric environment.

[0046] <Process (7)> Process (7) has a BET specific surface area of ​​20 m². 2 A zirconate compound (A) with a BET specific surface area of ​​less than 20 m² 2Mixing step (7) involves mixing zirconate compound (B) in amounts of 1 / g or more with zirconate compound (A) in such a ratio that the content ratio of zirconate compound (B) {B / (A+B)} in 100 ml of the total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%. Mixing can be done using wet mixing methods such as ball mills, bead mills, or spray mixing, or dry mixing methods such as paddle mixers, shaker mixers, or ball mills. From the viewpoint of dispersibility, mixability, and efficiency, wet mixing is preferred, and wet mixing using a ball mill is particularly preferred. In wet mixing, water, an organic dispersion medium, or a mixture thereof can be used as the dispersion medium. From the viewpoint of ease of handling and drying efficiency, methanol and ethanol are preferred as the organic dispersion medium.

[0047] <Process (8)> Step (8) is a step of drying the zirconate compound obtained in step (7). If step (7) was a wet mixing process, this process allows the dispersion medium to evaporate, thereby obtaining the zirconate compound powder. The drying method, drying temperature, drying time, and drying atmosphere are the same as in step (5).

[0048] The obtained zirconate compound powder can be used as a material for ceramic capacitors without grinding or crushing, but depending on the application, it may be ground or crushed and classified by known methods to prepare a graded product with a desired particle size. [Examples]

[0049] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0050] [Manufacturing of zirconate compound powder] The raw materials and apparatus used in the examples and comparative examples are as follows:

[0051] <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. • Barium carbonate (BaCO3): Manufactured by Kanto Chemical Co., Ltd. • Calcium carbonate (CaCO3): Manufactured by Shiraishi Calcium Co., Ltd. • Titanium dioxide (TiO3): "Super Titania (registered trademark) F-6", manufactured by Resonac Co., Ltd. • Silicon powder: Sigma-Aldrich, average particle size 15nm

[0052] <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 7000g, 3000rpm, 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. • Ball mill: "Tabletop Pot Mill ANZ-50S", manufactured by Nittokagaku Co., Ltd.; Beads used: 3mm diameter yttrium-stabilized zirconia beads (YTZ3Φ balls), rotation speed 70 rpm, peripheral speed 0.17 m / s

[0053] (Example 1) (1) Production of zirconate compound (A1) In a 500 mL fluororesin beaker at room temperature (25°C) in the atmosphere, 32.2 g (0.10 mol) of zirconium oxychloride octahydrate was added, and 200.0 g of pure water was added. The mixture was stirred to dissolve the zirconium oxychloride and prepare an aqueous solution. To the aqueous solution, a suspension of 7.4 g (0.10 mol) of calcium hydroxide added 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). The temperature of the suspension was maintained between room temperature (25°C) and 50°C.

[0054] The resulting reaction product was cooled to room temperature and then centrifuged in air at room temperature (25°C) using a centrifuge to generate 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 thorough washing and removal of the salts was confirmed by the conductivity of the supernatant being less than 50 μS / cm. In this way, a zirconium hydroxide (Zr(OH)4) slurry was obtained.

[0055] To 180 g of zirconium hydroxide slurry (Zr atom content 0.09 mol) containing the precipitate obtained as described above, 4.70 g (0.047 mol) of calcium carbonate, 9.87 g (0.05 mol) of barium carbonate, 0.80 g (0.01 mol) of titanium dioxide, and 5 g of dispersant were added. The resulting raw material mixture (Ca atoms + Ba atoms / Zr atoms + Ti atoms = 1 (molar ratio)) was wet-milled in a bead mill for 4 hours under air at room temperature to obtain a slurry-like raw material mixture.

[0056] The slurry-like raw material mixture was dried in a constant-temperature drying oven at 100°C in an atmospheric environment for 24 hours to obtain a dried raw material mixture.

[0057] 50g of the dried raw material mixture obtained above was placed on an alumina firing dish and heated in an electric furnace in an air atmosphere at a heating rate of 6°C / min to 1050°C. After firing at 1050°C for 2 hours, it was allowed to cool naturally to below 200°C, resulting in a specific surface area of ​​16.6m². 2 A zirconate compound (A1) of 1 / g was obtained. Compositional analysis described later revealed Ca 0.5 Ba 0.5 Zr 0.9 Ti 0.1 I confirmed that it was O3.

[0058] (2) Production of zirconate compound (B1) Similarly, 50g of the dried raw material mixture obtained above was placed on an alumina firing dish and heated in an electric furnace in an air atmosphere at a heating rate of 6°C / min to 950°C. After firing at 950°C for 2 hours, it was allowed to cool naturally to below 200°C, resulting in a specific surface area of ​​25.5m². 2 A zirconate compound (B1) of 1 / g was obtained. Compositional analysis revealed Ca 0.5 Ba 0.5 Zr 0.9 Ti 0.1 I confirmed that it was O3.

[0059] (3) Production of zirconate compound powder 9.8 g of the zirconate compound (A1) and 0.2 g of the zirconate compound (B1) obtained above, 50 g of ethanol, and 150 g of YTZ3Φ balls were placed in a 100 ml container and mixed in a ball mill at 70 rpm for 16 hours. The mixed slurry was dried on a hot plate at 50°C in air for 6 hours to obtain zirconate compound powder. Various evaluations were then performed. The results are summarized in Table 1.

[0060] (Example 2) A zirconate compound powder was obtained in the same manner as in Example 1, except that 9.6 g of zirconate compound (A1) and 0.4 g of zirconate compound (B1) were used. Various evaluations were then performed. The results obtained are summarized in Table 1.

[0061] (Example 3) A zirconate compound powder was obtained in the same manner as in Example 1, except that 9.2 g of zirconate compound (A1) and 0.8 g of zirconate compound (B1) were used. Various evaluations were then performed. The results obtained are summarized in Table 1.

[0062] (Example 4) A zirconate compound powder was obtained in the same manner as in Example 1, except that 8.4 g of zirconate compound (A1) and 1.6 g of zirconate compound (B1) were used. Various evaluations were then performed. The results obtained are summarized in Table 1.

[0063] (Example 5) A zirconate compound powder was obtained in the same manner as in Example 1, except that 5.0 g of zirconate compound (A1) and 5.0 g of zirconate compound (B1) were used. Various evaluations were then performed. The results obtained are summarized in Table 1.

[0064] (Comparative Example 1) 50g of the dried raw material mixture obtained in Example 1 was placed on an alumina firing dish and heated in an electric furnace in an air atmosphere at a heating rate of 6°C / min to 1100°C. After firing at 1100°C for 2 hours, it was allowed to cool naturally to below 200°C, resulting in a specific surface area of ​​10.3m². 2 A zirconate compound (A2) of 1 / g was obtained. Compositional analysis revealed Ca 0.5 Ba 0.5 Zr 0.9 Ti 0.1 I confirmed that it was O3. 9.8 g of the zirconate compound (A2) obtained above, 50 g of ethanol, and 150 g of YTZ3Φ balls were placed in a 100 ml container and mixed in a ball mill at 70 rpm for 16 hours. After mixing 0.2 g of silicon powder into the slurry, the mixture was dried on a hot plate at 50°C in air for 6 hours to obtain zirconate compound powder. Various evaluations were then performed. The results are summarized in Table 1.

[0065] (Comparative Example 2) A zirconate compound powder was obtained by processing under the same conditions as in Comparative Example 1, except that 9.6 g of zirconate compound (A2) and 0.4 g of silicon powder were used. Various evaluations were then performed. The results are summarized in Table 1.

[0066] (Comparative Example 3) 50g of the dried raw material mixture obtained in Example 1 was placed on an alumina firing dish and heated in an electric furnace in an air atmosphere at a heating rate of 6°C / min to 925°C. After firing at 925°C for 2 hours, it was allowed to cool naturally to below 200°C, resulting in a specific surface area of ​​28.0 m². 2 A zirconate compound (B2) of / g was obtained. Compositional analysis revealed Ca 0.5 Ba 0.5 Zr 0.9 Ti 0.1 I confirmed that it was O3. A zirconate compound powder was obtained by processing under the same conditions as in Comparative Example 1, except that 9.8 g of zirconate compound (B2) and 0.2 g of silicon powder were used. Various evaluations were then performed. The results are summarized in Table 1.

[0067] (Comparative Example 4) A zirconate compound powder was obtained by processing under the same conditions as in Comparative Example 1, except that 9.6 g of zirconate compound (B2) and 0.4 g of silicon powder were used. Various evaluations were then performed. The results are summarized in Table 1.

[0068] (Reference examples 1~4) Various evaluations were performed on each of the following: elemental zirconate compound (A2) (Reference Example 1), elemental zirconate compound (B2) (Reference Example 2), elemental zirconate compound (A1) (Reference Example 3), and elemental zirconate compound (B1) (Reference Example 1). The results obtained are summarized in Table 1.

[0069] [evaluation] (Composition (atomic content)) The zirconate compound powder was analyzed for its composition by measuring its XRF spectrum using the Simultix 14 multi-element simultaneous X-ray fluorescence analyzer (manufactured by Rigaku Corporation), and its constituent atomic composition was confirmed.

[0070] (BET specific surface area) In accordance with JIS R 1626:1996, the BET specific surface area of ​​zirconate compounds (A1), (A2), (B1), (B2), and zirconate compound powder was measured using a fully automated BET specific surface area analyzer ("Macsorb® HM model-1208", manufactured by Mountec Co., Ltd.). As a pretreatment, the zirconate compound or zirconate compound powder was heated to 180°C, then cooled to room temperature (25°C) by flowing nitrogen gas through it for 20 minutes to obtain a sample. For this sample, the BET specific surface area was measured using the BET 3-point method with nitrogen gas as the adsorbate. The applicable range of the BET method was set to P / P0 = 0.00 to 0.95.

[0071] (pore volume) As a pretreatment, zirconate compound powder was heated to 180°C, then cooled to room temperature (25°C) by flowing nitrogen gas through it for 20 minutes to obtain a sample. For this sample, the pore volume (pore volume from 1.5 nm to 50.5 nm (ml / g)) was measured using nitrogen gas with a NOVA4200e manufactured by Quantachrome, in accordance with JIS Z 8831-3:2010 (Method for measuring micron pores by gas adsorption).

[0072] (Shrinkage rate) 1.50 g of the obtained zirconate compound powder was weighed, placed in a Φ30 mm circular mold, and compressed at 20 MPa to obtain pellets. The diameter of the obtained pellets was measured. The pellets were then placed on an alumina firing dish and heated in an electric furnace in an air atmosphere at a heating rate of 5°C / min to 1200°C. After maintaining the temperature for 2 hours, the heater was cut off and the pellets were allowed to cool naturally to obtain a sintered pellet body. The diameter of the obtained sintered pellet body was measured. The shrinkage rate was calculated from (diameter of pellet before sintering mm - diameter of sintered pellet body mm) / (diameter of sintered pellet body mm).

[0073] (Simple average of contraction rates) The simple average shrinkage rate of zirconate compound powder (a mixture of zirconate compound (A) x parts by mass and zirconate compound (B) y parts by mass) is the shrinkage rate of zirconate compound (A) (S A ) and the shrinkage rate (S) of the zirconate compound (B) B ) and the weighted average value obtained by their respective mixing ratios (mass ratios) ((S A ·x+S B The value is (x + y) / (x + y). If the shrinkage rate is higher than this value, it can be seen that mixing zirconate compound (A) and zirconate compound (B) and sintering them can increase the shrinkage rate.

[0074] (Rate of contraction increase) The "shrinkage rate / simple average shrinkage rate" is defined as the shrinkage rate increase rate. This represents how much the shrinkage rate has increased compared to the simple average shrinkage rate. If this value exceeds 100%, it can be said that the addition of zirconate compound (B) has the effect of promoting an increase in the shrinkage rate compared to zirconate compound (A).

[0075] [Table 1]

[0076] Comparative Examples 1 and 2 involved adding 2 mol% or 4 mol% of silicon powder, commonly used as a sintering aid, to zirconate compound (A2). However, the shrinkage rate decreased compared to the case of zirconate compound (A2) alone (Reference Example 1). This indicates that silicon powder does not act as a sintering aid for zirconate compound (A2). Comparative Examples 3 and 4 involved adding 2 mol% or 4 mol% of silicon powder, which is commonly used as a sintering aid, to the zirconate compound (B2). However, the shrinkage rate decreased compared to the case of zirconate compound (B2) alone (Reference Example 2). This indicates that the silicon powder does not act as a sintering aid for zirconate compound (B2). On the other hand, the zirconate compound powder obtained by mixing zirconate compound (A1) and zirconate compound (B1) from Examples 1 to 5 showed improved shrinkage compared to the case of zirconate compound (A) alone (Reference Example 3). Furthermore, the shrinkage rates of the zirconate compound powders from Examples 1 to 5 were greater than the simple average shrinkage rate calculated simply from the mixing ratio of zirconate compound (A1) and zirconate compound (B1). From these results, a BET specific surface area of ​​20 m² was obtained. 2 A zirconate compound (A) with a BET specific surface area of ​​less than 20 m² 2 It can be seen that when zirconate compound powder is mixed with zirconate compound (B) at a ratio of 0.1 mol% to 50 mol% of B / (A+B), the shrinkage rate during sintering is significantly improved.

Claims

1. Perovskite structure ABO ３ It has a BET specific surface area of ​​20 m², with at least one atom selected from the group consisting of barium, strontium, and calcium in site A, and zirconium in site B. ２ Zirconate compounds (A) that are less than / g, and Perovskite structure ABO ３ It has a BET specific surface area of ​​20 m², with at least one atom selected from the group consisting of barium, strontium, and calcium in site A, and zirconium in site B. ２ Zirconate compounds (B) that are 1 / g or more Includes, A zirconate compound powder in which the content ratio of zirconate compound (B) {B / (A+B)} in a total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%.

2. The zirconate compound powder according to claim 1, wherein the cumulative value of pore volumes in the range of pore diameters from 1.5 to 50.5 nm in the pore distribution curve is 0.01 ml / g or more and 0.27 ml / g or less.

3. A solid electrolyte sintered body obtained by sintering the zirconate compound powder according to claim 1 or 2.

4. Perovskite structure ABO ３ It has a BET specific surface area of ​​20 m², with at least one atom selected from the group consisting of barium, strontium, and calcium in site A, and zirconium in site B. ２ A zirconate compound (A) with a concentration of less than / g and a perovskite structure ABO ３ It has a BET specific surface area of ​​20 m², with at least one atom selected from the group consisting of barium, strontium, and calcium in site A, and zirconium in site B. ２ A method for producing zirconate compound powder, comprising a mixing step (7) of mixing zirconate compound (B) in a quantity of 1 / g or more with zirconate compound (A) in a proportion such that the content ratio of zirconate compound (B) {B / (A+B)} in 100 mol% of the total amount of zirconate compound (A) and zirconate compound (B) is 0.1 to 50 mol%.

5. A method for producing a zirconate compound powder according to claim 4, comprising, before step (7) above, a step (4) of mixing at least one compound selected from a barium-containing compound, a strontium-containing compound, and a calcium-containing compound with a zirconium-containing compound to obtain a raw material mixture, and a step (6) of calcining the raw material mixture at 700°C or higher to obtain zirconate compound (A) and zirconate compound (B).

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