JP2021042094A - Zirconic acid-based perovskite type composite oxide particle and method for producing the same - Google Patents

Abstract

To provide a method for producing fine and highly crystalline zirconic acid-based perovskite type composite oxide particles by a hydrothermal method.SOLUTION: A method is provided for producing, by a hydrothermal method, zirconic acid-based perovskite type composite oxide particles represented by a composition formula (I) ABxO3-δ (In the formula, A is at least one kind of element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9≤x≤1.1, and δ is an oxygen deficiency amount). The method comprises the steps of (a) obtaining a first slurry by mixing hydroxide of an element A, zirconium hydroxide and seed crystals of a zirconic acid-based perovskite type composite oxide containing the element A with water, (b) obtaining a second slurry containing a particulate solid having an average particle diameter of 2.0 μm or less by wet grinding the first slurry, (c) obtaining a third slurry by adding a hydroxide of the element A to the second slurry, (d) obtaining a fourth slurry by hydrothermal reaction of the third slurry, and (e) subjecting the fourth slurry to acid treatment and then washing with water to remove an excess hydroxide of the element A. An element A/B molar ratio of the first slurry is 0.1 or more in the step (a), and an A/B molar ratio of the third slurry is 1.2 or more in the step (c).SELECTED DRAWING: None

Description

The present invention relates to a zirconate-based perovskite-type composite oxide particle and a method for producing the same. Specifically, the present invention is a zirconate-based perovskite-type composite that is fine, has a crystallite diameter / specific surface area equivalent particle diameter close to 1, and is highly crystalline. Regarding oxide particles and their production methods.

Zirconate-based perovskite-type composite oxide particles such as barium zirconate and strontium zirconate are widely used as derivatives due to their high dielectric constant. In particular, in recent years, particles having a small particle diameter or crystallite diameter have been required due to the demand for high dispersibility in a matrix resin.

Conventionally, a solid-phase method and a solvothermal method are well known as a method for producing the zirconate-based perovskite-type composite oxide.

However, according to the solid-phase method, a high calcination temperature is required to make the crystal phase of the obtained reactant monophasic, and therefore it is difficult to obtain a zirconate-based perovskite-type composite oxide as a fine powder. is there.

Of course, the obtained zirconate-based perovskite-type composite oxide can be subjected to wet pulverization to be finely divided, but on the other hand, the A-site element is eluted from the composite oxide during the wet pulverization. In addition, contamination of the composite oxide derived from the pulverized media may occur, and the electrical characteristics of the composite oxide may deteriorate.

Further, as an example of the solvothermal method, for example, a precursor of element A containing barium and strontium, a precursor of element B containing Ti and Zr, and amines can be used as A / B mol in the obtained perovskite-type composite oxide. The mixture was mixed so that the ratio was greater than 1, and reacted at a temperature in the range of 100 to 240 ° C. in the presence of an oxygen-containing organic solvent to obtain a slurry-like synthetic solution containing a solid content, which was described as, for example, acrylic acid. A method of obtaining the desired perovskite-type composite oxide by treating with the alcohol solution of the above can be mentioned (see Patent Document 1).

However, in the solvothermal method, in order to obtain fine perovskite-type composite oxide particles, as described above, an organic substance is used during the pretreatment and the reaction, which increases the production cost and the above. There is a problem that waste liquid treatment costs including organic substances are incurred.

Further, there is also known a method of obtaining barium dilconate particles whose average particle size can be controlled in the range of 0.2 to 0.35 μm by a hydrothermal method using a seed crystal of barium dilconate (Non-Patent Document). 1). However, since this method uses a zirconium-triethanolamine complex as the zirconium source, there are problems in terms of manufacturing cost and waste liquid treatment, similar to the above-mentioned solvothermal method.

Japanese Unexamined Patent Publication No. 2019-26542

K. Kanie et al., Size-controlled hydrothermal synthesis of monodispersedBaZrO3 sphere particles by seeding, Advanced Powder Technology, 28 (1), 55-60, 2017

The present invention has been made to solve the above-mentioned problems in the production of a zirconate-based perovskite-type composite oxide, and is fine, has a crystallite diameter / specific surface area equivalent particle diameter close to 1, and has high crystallinity. It is an object of the present invention to provide a method for producing zirconate-based perovskite-type composite oxide particles, which is a zirconate titer, by a hydrothermal method without using an organic substance. Furthermore, an object of the present invention is to provide zirconate-based perovskite-type composite oxide particles having the above-mentioned characteristics.

According to the present invention, the composition formula (I)
AB _x O _3-δ
(In the formula, A is at least one element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9 ≦ x ≦ 1.1, and δ is oxygen. The amount of deficiency.)
A method for producing zirconate-based perovskite-type composite oxide particles represented by.
(A) A step of mixing a hydroxide of element A, a zirconium hydroxide, and a seed crystal of a zirconic acid-based perovskite-type composite oxide containing the element A with water to obtain a first slurry.
(B) A step of wet-pulverizing the first slurry to obtain a second slurry containing a particulate solid having an average particle diameter of 2.0 μm or less.
(C) A step of adding a hydroxide of element A to the second slurry to obtain a third slurry.
(D) The step of hydrothermally reacting the third slurry to obtain a fourth slurry, and (e) the fourth slurry is acid-treated and then washed with water to obtain excess water of the element A. Including the step of removing oxides
In the above step (a), the A / B molar ratio of the first slurry is set to 0.1 or more.
In the step (c), a method for producing zirconate-based perovskite-type composite oxide particles is provided, wherein the A / B molar ratio of the third slurry is 1.2 or more.

In the present invention, the A / B molar ratio means the (Ba and / or Sr) / Zr molar ratio depending on the hydroxide of the element A used, that is, the hydroxide of Ba and / or Sr.

According to the present invention, in the step (a), the seed crystal is used in the range of 1 to 20 mol parts with respect to 100 mol parts of zirconium in the zirconium hydroxide contained in the first slurry. Is desirable.

Further, according to the present invention, the hydrothermal reaction is preferably carried out in a temperature range of 120 to 300 ° C.

Further, according to the present invention, the composition formula (I)
AB _x O _3-δ
(In the formula, A is at least one element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9 ≦ x ≦ 1.1, and δ is oxygen. The amount of deficiency.)
Provided are zirconic acid-based perovskite-type composite oxide particles having a specific surface area of 12 m ² / g or more and a crystallite diameter / specific surface area equivalent particle diameter in the range of 0.7 to 1.3.

According to the method of the present invention, it is possible to obtain zirconate-based perovskite-type composite oxide particles that are fine, have a crystallinity diameter / specific surface area equivalent particle diameter close to 1, and are highly crystalline.

Since the zirconate-based perovskite-type composite oxide particles according to the present invention have such characteristics, they have a high dielectric constant, and therefore can contribute to the miniaturization of the multilayer capacitor in particular.

Further, unlike the solvothermal method, since no organic substance is used, there is no need for waste liquid treatment, and the manufacturing cost can be suppressed at a lower cost as compared with the solvothermal method.

The method for producing zirconate-based perovskite-type composite oxide particles according to the present invention is described in the composition formula (I).
AB _x O _3-δ
(In the formula, A is at least one element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9 ≦ x ≦ 1.1, and δ is oxygen. The amount of deficiency.)
A method for producing zirconate-based perovskite-type composite oxide particles represented by.
(A) A step of mixing a hydroxide of element A, a zirconium hydroxide, and a seed crystal of a zirconic acid-based perovskite-type composite oxide containing the element A with water to obtain a first slurry.
(B) A step of wet-pulverizing the first slurry to obtain a second slurry containing a particulate solid having an average particle diameter of 2.0 μm or less.
(C) A step of adding a hydroxide of element A to the second slurry to obtain a third slurry.
(D) The step of hydrothermally reacting the third slurry to obtain a fourth slurry, and (e) the fourth slurry is acid-treated and then washed with water to obtain excess water of the element A. Including the step of removing oxides
In the above step (a), the A / B molar ratio of the first slurry is set to 0.1 or more.
The step (c) is characterized in that the A / B molar ratio of the third slurry is 1.2 or more.

In the present invention, the A / B molar ratio in the steps (a) and (c) is the amount of barium hydroxide and / or strontium hydroxide and zirconium hydroxide used in each step, that is, the amount charged. based on. On the other hand, the A / B molar ratio in the zirconate-based perovskite-type composite oxide particles finally obtained in the present invention is based on the analysis method described later.

In the method for producing zirconate-based perovskite-type composite oxide particles according to the present invention, in the steps (a) and (c), the steps are performed while adjusting the A / B molar ratio of the obtained slurry to a predetermined value. A slurry is obtained from (a) through step (c), and this slurry is subjected to a hydrothermal reaction in step (d) to obtain the desired fine and highly crystalline zirconate-based perovskite-type composite oxide particles. Obtainable.

In the present invention, examples of the barium hydroxide include anhydrous barium hydroxide, monohydrate, and octahydrate. Examples of the strontium hydroxide include anhydrous strontium hydroxide and octahydrate.

As the zirconium hydroxide, commercially available products of anhydrous zirconium hydride and various hydrates can be used. However, the above-mentioned commercial product easily absorbs water and is unstable. Therefore, in the present invention, as the zirconium hydroxide, a water-soluble zirconium compound such as zirconium oxychloride, zirconium acetate, or zirconium sulfate is used in an excess amount of an alkaline compound such as sodium hydroxide, potassium hydroxide, or aqueous ammonia and in water. It is preferable to react to generate zirconium hydroxide almost quantitatively, and to use the zirconium hydroxide as the wet cake thus obtained.

Seed crystal particles of barium hydroxide and / or strontium hydroxide, zirconate hydroxide and zirconate-based perovskite-type composite oxide, that is, barium zirconate and / Or Even if the seed crystal particles of strontium zirconate are slurried in water and subjected to a hydrothermal reaction in step (d), the zirconate-based perovskite-type composite oxide particles that are the object of the present invention cannot be obtained. ..

Hereinafter, a method for producing zirconate-based perovskite-type composite oxide particles according to the present invention will be described for each step.

In step (a), barium hydroxide and / or strontium hydroxide, zirconium hydroxide, and seed crystals of barium zirconate and / or strontium zirconate are mixed with water to obtain a first slurry. It is a process.

The seed crystal particles of the zirconate-based perovskite-type composite oxide used in the step (a) are preferably selected in composition according to the target zirconate-based perovskite-type composite oxide. For example, the case of obtaining a BaZrO ₃ high purity, using a seed crystal of BaZrO _3, the case of obtaining SrZrO _3, it is preferable to use seed crystals of SrZrO _3.

The amount of the seed crystal added is preferably in the range of 1 to 20 mol parts with respect to 100 mol parts of zirconium in the zirconium hydroxide contained in the first slurry. When the amount added is less than 1 mol part with respect to 100 mol parts of zirconium in the zirconium hydroxide contained in the first slurry, ^{the specific surface area is 12 m 2} / g or more, preferably 20 m ² / g or more. It is not possible to obtain zirconate-based perovskite-type composite oxide particles having the above. When the amount added exceeds 20 mol parts with respect to 100 mol parts of zirconium in the zirconium hydroxide contained in the first slurry, it takes a long time to pulverize, which makes it economical as an industrial production method. In addition to causing problems, impurities derived from the pulverization medium may be mixed into the pulverized product.

In the step (a), the A / B molar ratio of the first slurry is 0.1 or more. In step (a), when barium hydroxide and / or strontium hydroxide is used at a value having an A / B molar ratio smaller than 0.1, it is 12 m ² / g or more, preferably 20 m ² /. In order to obtain a zirconate-based perovskite-type composite oxide particle having a specific surface area of g or more, pulverization for a very long time is required in the step (b). As a result, impurities derived from the pulverized media are mixed in the obtained pulverized product, and finally it is not possible to obtain high quality zirconate-based perovskite-type composite oxide particles.

According to the present invention, in the step (a), the A / B molar ratio of the first slurry may be 0.1 or more. There is no particular upper limit to the A / B molar ratio, but in step (c) described later, barium hydroxide and / or strontium hydroxide is added to determine the A / B molar ratio of the obtained slurry. Since it is necessary to set the ratio to 2 or more, in the step (a), the A / B molar ratio of the first slurry may be less than 1.2, and is usually 1.1 or less, preferably 1. 0 or less is sufficient.

The step (b) is a step of wet-pulverizing the first slurry to obtain a second slurry containing a particulate solid having an average particle diameter of 2.0 μm or less.

In step (b), when the particulate solid in the obtained second slurry has an average particle size of more than 2.0 μm, the target fine and highly crystalline zirconate-based perovskite-type composite oxide particles Cannot be obtained.

In the step (b), the lower limit of the average particle size of the particulate solid matter in the obtained slurry is not particularly limited, but is usually preferably about 0.1 μm. When the average particle size of the particulate solid matter in the obtained slurry is made too small in the step (b), it takes an unnecessarily long time for pulverization, which is economically problematic as an industrial production method. In addition to this, impurities derived from the pulverized medium may be mixed into the pulverized product.

A planetary ball mill or a bead mill is usually used for the wet pulverization in the step (b). As the pulverization medium, zirconia balls having an appropriate diameter, for example, a diameter of about 0.3 to 3.0 mm, or the like is preferably used in consideration of the required average particle diameter.

Step (c) is a hydrothermal reaction in which barium hydroxide and / or strontium hydroxide is added to the second slurry obtained in step (b) to have excess barium and / or strontium. This is a step of obtaining a third slurry containing a raw material mixture for the purpose.

That is, the third slurry contains excess barium hydroxide and / or strontium hydroxide as well as zirconium hydroxide. Here, the fact that the third slurry has an excess of barium and / or strontium means that the amount of barium and / or the amount of strontium exceeds 1 mol by mole with respect to 1 mol of zirconium contained in the third slurry. Is. That is, in the step (c), it is preferable that the A / B molar ratio of the obtained third slurry is 1.2 or more.

When the molar ratio is smaller than 1.2, barium and / or strontium does not sufficiently react with zirconium in the hydrothermal reaction in the next step (d), and the obtained barium zirconate and / or strontium A / The B molar ratio may be lower than the target value, and the crystallinity may be lowered. In the present invention, the molar ratio is particularly preferably in the range of 1.3 to 2.5.

In the step (c), the A / B molar ratio was set to 1.2 or more, and in the next step (d), the surplus barium hydroxide and / or the strontium hydroxide that did not participate in the hydrothermal reaction was removed from the step. In (e), since it is removed from the reaction system by acid treatment and washing with water, the upper limit of the A / B molar ratio is not particularly limited. However, usually, the A / B molar ratio is preferably 5.0 or less, and more preferably 3.0 or less.

Even if the molar ratio exceeds 5.0, the desired zirconate-based perovskite-type composite oxide particles can be obtained. However, even with too much barium and / or strontium, they are no longer involved in the hydrothermal reaction, and in the next step (e), after acid treatment of the fourth slurry obtained by the hydrothermal reaction. , Removed by washing with water. Thus, the excess barium and / or strontium requires the use of a large amount of acid and water for the acid treatment and the subsequent washing treatment, respectively, which has the disadvantage of increasing the production cost.

The step (d) is a step of hydrothermally reacting the third slurry obtained in the step (c) to obtain a fourth slurry. The temperature of this hydrothermal reaction is usually in the range of 120 to 300 ° C, preferably in the range of 130 to 250 ° C, and most preferably in the range of 150 to 230 ° C.

The fourth slurry contains zirconate-based perovskite-type composite oxide particles produced from the raw material mixture by a hydrothermal reaction in the presence of excess barium hydroxide and / or strontium hydroxide.

Therefore, in the step (e), the fourth slurry obtained by the hydrothermal reaction is acid-treated and then washed with water. That is, in the step (e), an acid such as nitric acid is added to the fourth slurry, and the excess barium hydroxide and / or strontium water is added from the obtained zirconic acid-based perovskite-type composite oxide particles. The step of removing the oxide as a water-soluble salt such as barium nitrate and / or strontium nitrate.

Thus, the fourth slurry is acid-treated, then washed with water, and if necessary, filtered and dried to obtain zirconate-based perovskite-type composite oxide particles that do not contain barium carbonate and / or strontium as heterogeneous phases. Obtainable.

The acid used for the acid treatment may be either an inorganic acid or an organic acid, but usually nitric acid, hydrochloric acid, acetic acid and the like are preferably used. The reaction mixture obtained in step (e) is acid-treated so as to have a pH of about 8. Further, ion-exchanged water or pure water is preferably used for the water washing treatment. The water washing treatment is preferably carried out until the electrical conductivity of the filtrate becomes 5 ms / m or less.

According to the present invention, in this way, the single-phase particles represented by the composition formula (I) ^{have a specific surface area of 12 m 2} / g or more, are fine, and are 0.7. It is possible to obtain zirconate-based perovskite-type composite oxide particles having a crystallite diameter / specific surface area equivalent particle diameter in the range of about 1.3 and having excellent crystallinity.

According to a preferred embodiment, the zirconic acid-based perovskite-type composite oxide particles according to the present invention ^{have a specific surface area of 20 m 2} / g or more, are fine, and have a crystallite diameter / specific surface area equivalent particle diameter of 1. It has a crystallite diameter / specific surface area equivalent particle diameter in the range of 0.9 to 1.3, which is a close value, and is excellent in crystallinity. Generally, the closer the crystallite diameter / specific surface area conversion particle diameter is to 1, the closer the geometric particle diameter is to the size of the single crystal, and therefore the particles are more crystallinity.

Usually, the specific surface area equivalent diameter of a particle is larger than the crystallite diameter. That is, the value of the crystallite diameter / specific surface area equivalent particle diameter is often smaller than 1, but the specific surface area equivalent diameter is calculated assuming that each particle is spherical, so the particle shape is not spherical. In this case, the value of the crystallite diameter / specific surface area equivalent particle diameter may be larger than 1 due to the influence of the difference from the actual particle shape.

According to the present invention, when the amount of barium and / or the amount of strontium in the obtained zirconate-based perovskite-type composite oxide particles is deficient, that is, when the A / B molar ratio is less than 1, the above-mentioned zirconate The perovskite-type composite oxide can be supplemented with barium and / or strontium to obtain zirconate-based perovskite-type composite oxide particles having a desired A / B molar ratio.

That is, for example, after a hydrothermal reaction, the obtained reaction mixture (solid) is filtered, acid-treated, washed with water, and barium hydroxide and / or strontium hydroxide dissolved in water in the reaction mixture. After removing the substance, the A / B molar ratio of the obtained reaction product is analyzed, and then a barium compound and / or a strontium compound is added to the reaction product so as to obtain a desired A / B molar ratio. In addition as an agent, each of them has a desired A / B molar ratio, and when this is sintered, a zirconic acid-based perovskite-type composite oxide sintered body having a desired A / B molar ratio can be obtained.

The above-mentioned additives have low solubility in water, and even if the additives are thermally decomposed when the reaction mixture to which the additives are added is sintered in this way, those other than barium and / or strontium are used. Those that do not remain in the sintered body, for example, carbonates, organic acid salts, oxides, and the like are preferably used.

The zirconate-based perovskite-type composite oxide sintered body preferably has an alkali metal content of not exceeding 0.03% by mass. When the content of the alkali metal exceeds 0.03% by mass, the dielectric constant may not reach the target value, or the defective rate of the obtained capacitor may increase.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. In the following, unless otherwise specified, "part" means "part by mass" and "%" means "% by mass". In addition, various measurements were performed as follows.

Particle size distribution and average particle size of particulate solids in the second slurry in step (b) A part of the second slurry obtained in step (b) was fractionated and used as a sample, and sodium hexametaphosphate was used as a sample. As a dispersant, disperse with an ultrasonic homogenizer, and use a light diffraction / scattering method, that is, a laser diffraction / scattering particle size distribution meter (MT-3300 EXII manufactured by Microtrac Bell Co., Ltd.) to: It was measured under the conditions of.

Measurement mode: MT-3000
Upper limit of measurement: 1408 μm
Lower limit of measurement: 0.021 μm
Refractive index of particles: 2.07
Particle shape: Non-spherical Solvent refractive index: 1.333

The volume median diameter (medium volume diameter) obtained in the measurement of the particle size distribution was taken as the average particle diameter.

Specific surface area The specific surface area was measured by the BET flow method using a specific surface area measuring device (Macsorb HM-1220 manufactured by Mountech Co., Ltd.). Pure nitrogen was used as the adsorbed gas, and the mixture was held at 230 ° C. for 30 minutes.

Powder X-ray diffraction pattern The powder X-ray diffraction pattern was measured under the following conditions by a powder X-ray diffractometer (manufactured by Rigaku Corporation, sample horizontal strong X-ray diffractometer RINT-TTRIII).

Optical system: Parallel beam optical system (long slit: PSA200 / opening angle: 0.057 degrees)
Tube voltage: 50kV
Current: 300mA
Measurement method: Parallel method (continuous)
Measurement range (2θ): 10 to 60 degrees Sampling width: 0.04 degrees Scan speed: 5 degrees / minute

Crystallite diameter From the half-value width of the diffraction line with respect to the perovskite phase (400) plane of strontium zirconate or the (200) plane of the perovskite phase of barium zirconate in the X-ray diffraction pattern measured by the method described above. The crystallite diameters were calculated using the formulas.

Crystallite diameter = K × λ / βcosθ
However,
K = Scheller constant (= 0.94)
λ = X-ray wavelength (Cu-Kα line 1.5418 Å)
β = half price range (radian unit)
θ = Bragg angle (1/2 of the diffraction angle 2θ)

Specific surface area equivalent particle size From the specific surface area measured by the above method, the specific surface area equivalent particle size was calculated using the following conversion formula.

S = 6 / (ρ × d)
S = Specific surface area ρ = Sample powder density d = Specific surface area equivalent particle size However, ρ (density of sample powder) is the theoretical density, SrZrO ₃ is 5.23 g / cm ³ , and BaZrO ₃ is 5. It is 70 g / cm ³ .

A / B molar ratio analysis (pretreatment) of the obtained zirconate-based perovskite-type composite oxide particles by ICP emission spectroscopy.
0.2 g of the obtained perovskite-type composite oxide particles were weighed in a platinum crucible, and then 1 g of lithium borate (Fuji Film Wako Pure Chemical Industries, Ltd.) was weighed. 25 g of potassium bromide (Fuji Film Wako Pure Chemical Industries, Ltd.) was weighed in a beaker, 75 mL of ion-exchanged water was added, and the mixture was stirred and dissolved with a glass rod to prepare a 25% aqueous potassium bromide solution. 20 μL of this 25% potassium bromide aqueous solution was dispensed with a micropipettor, and the perovskite-type composite oxide particles and lithium tetraborate were added to the weighed platinum crucible. The platinum crucible was attached to a bead & fuse sampler (TK-4100 type high frequency melting device manufactured by Amena Tech Co., Ltd.), and the contents of the crucible were heated and melted at 1000 ° C. After heating and melting, a stirrer, 10 mL of hydrochloric acid (for precision analysis manufactured by Kanto Chemical Co., Ltd.) and 20 mL of ion-exchanged water were added to the platinum crucible, and the mixture was heated to 120 ° C. and dissolved while stirring with a hot stirrer. After this, the obtained lysate was transferred to a Teflon beaker and heated again at 120 ° C. The dissolved sample was transferred to a 100 mL nylon volumetric flask, and 10 mL of a 100 ppm scandium standard solution (Fuji Film Wako Pure Chemical Industries, Ltd.) was added as an internal standard to adjust the volume to 100 mL, and a sample was obtained.
(Measurement)
The molar concentration of each element was measured by the calibration curve method using the ICP emission spectroscopic analyzer (SPS-3100, manufactured by Hitachi High-Tech Science Co., Ltd.), and the composition ratio was calculated.

Permittivity The quartz tube of a 1 GHz hollow resonator (manufactured by AET Co., Ltd.) is filled with perovskite oxide particles, and the high-frequency dielectric constant is measured with a compact network analyzer MS46122B (manufactured by Anritsu Co., Ltd.) to determine the permittivity. Obtained.

In the above measuring method, the dielectric constant was measured according to JIS-2565 “Ferrite core test method for microwaves”.

Manufacturing example 1
(Manufacture of wet cake of zirconium hydroxide)
84.65 g of zirconium oxychloride octahydrate (manufactured by Yoneyama Yakuhin Kogyo Co., Ltd.) and 1.42 L of ion-exchanged water were added to a glass beaker, and the mixture was stirred and dissolved to obtain an aqueous solution. Further, 79.98 g of sodium hydroxide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 4 L of ion-exchanged water were added to a nylon beaker, and the mixture was stirred and dissolved to obtain an aqueous solution.

The above zirconium oxychloride aqueous solution was added to a beaker equipped with another stirrer containing 600 mL of ion-exchanged water at 45 mL / min using a tube pump, and the pH was adjusted to 8.5 to 9.5. The sodium hydroxide aqueous solution was added to the beaker using another tube pump.

After completion of the addition, the mixture was stirred as it was for 1 hour to obtain a slurry. Then, the obtained slurry was filtered, and the obtained solid substance was washed with ion-exchanged water until the electric conductivity of the filtrate became 5 ms / m or less, and 401 g of a wet cake of zirconium hydroxide (hydroxylide) was washed. A concentration of 10.42% and a yield of 97%) were obtained.

Since zirconium hydroxide easily absorbs moisture and it is difficult to accurately weigh the concentration of zirconium hydroxide in the obtained wet cake, the concentration of zirconium hydroxide in the wet cake is as follows. I asked for it. That is, the zirconium concentration in the oxide residue when the wet cake was heated to 500 ° C. was determined, and these were _{converted into hydroxide, that is, Zr (OH) 4} , and the concentration and yield of hydroxide were obtained. I asked. It was confirmed by thermogravimetric analysis that the physically adsorbed water and the hydroxyl groups were completely removed and the oxide was formed by heating the cake to 500 ° C.

Manufacturing example 2
(Production of seed crystals of strontium zirconate)
91.65 g of the zirconium hydroxide wet cake obtained in Production Example 1 was dispensed into a titanium container, and 21.21 g of strontium hydroxide octahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was further added thereto. And 0.1 L of ion-exchanged water were added to the mixture and stirred to obtain a slurry.

The titanium container was placed in an autoclave and heated at 200 ° C. for 2 hours to cause a hydrothermal reaction between the zirconium hydroxide and strontium hydroxide. The obtained slurry was transferred to a polyethylene beaker equipped with a stirrer, a 0.2% aqueous nitric acid solution was added thereto, the pH was adjusted to 7, and the mixture was stirred as it was for 30 minutes. At this time, since the pH of the slurry increased, the pH of the slurry was readjusted to 7 by adding a 0.2% aqueous nitric acid solution again.

This slurry is filtered, the obtained solid substance is washed with ion-exchanged water until the electrical conductivity of the filtrate becomes 3 ms / m or less, and the resulting cake is dried in a dryer set at a temperature of 150 ° C. for 10 hours. Then, strontium zirconate particles represented by the composition formula SrZrO _{3 were obtained as seed crystals.}

Manufacturing example 3
(Manufacturing seed crystals of barium zirconate)
45.82 g of the wet cake of zirconium hydroxide obtained in Production Example 1 was dispensed into a titanium container, and 18.93 g of barium hydroxide octahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was further added thereto. And 0.1 L of ion-exchanged water were added to the mixture and stirred to obtain a slurry.

The titanium container was placed in an autoclave and heated at 200 ° C. for 2 hours to cause a hydrothermal reaction between the zirconium hydroxide and barium hydroxide. The obtained slurry was transferred to a polyethylene beaker equipped with a stirrer, a 0.2% aqueous nitric acid solution was added thereto, the pH was adjusted to 8, and the mixture was stirred as it was for 30 minutes. At this time, since the pH of the slurry increased, the pH of the slurry was readjusted to 8 by adding a 0.2% aqueous nitric acid solution again.

This slurry is filtered, the obtained solid substance is washed with ion-exchanged water until the electrical conductivity of the filtrate becomes 3 ms / m or less, and the resulting cake is dried in a dryer set at a temperature of 150 ° C. for 10 hours. Then, barium zirconate particles represented by the composition formula BaZrO _{3 were obtained as seed crystals.}

Example 1
(Manufacturing of strontium zirconate particles)
Step (a)
91.65 g of the wet cake of zirconium hydroxide obtained in Production Example 1 was dispensed into a plastic container having a capacity of 300 mL, and 9.30 g of strontium hydroxide octahydrate (Fuji Film Wako Pure Chemical Industries, Ltd.) was further added thereto. The first slurry was obtained by adding 1.36 g of strontium zirconate seed crystals obtained in Production Example 2, 50 mL of ion-exchanged water and 30 mL of zirconia beads having a diameter of 0.5 mm.

Step (b)
The plastic container was placed in a planetary ball mill (P-5 manufactured by Fritsch) and operated at a rotation speed of 250 rpm for 30 minutes to wet-pulverize the first slurry. The beads were removed from the obtained slurry by a sieve to obtain a slurry, and this slurry was transferred to a titanium container. Thus, a second slurry containing a particulate solid having an average particle diameter of 0.59 μm was obtained.

Step (c)
Subsequently, 14.62 g of strontium hydroxide octahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 0.1 L of ion-exchanged water were added to the titanium container, and the mixture was stirred to generate water heat as a third slurry. A slurry before the reaction was obtained.

Step (d)
The titanium container containing the third slurry before the hydrothermal reaction was placed in an autoclave as it was, heated at 200 ° C. for 2 hours, and hydrothermally reacted to obtain a fourth slurry.

Process (e)
The fourth slurry was transferred to a polyethylene beaker equipped with a stirrer, a 0.2% aqueous nitric acid solution was added to adjust the pH of the slurry to 8, and the mixture was stirred as it was for 30 minutes. At this time, since the pH of the slurry increased, the pH was readjusted to 8 by adding a 0.2% nitric acid aqueous solution to the slurry again.

After that, the slurry is filtered, and the obtained solid matter is washed with ion-exchanged water until the electrical conductivity of the filtrate becomes 3 ms / m or less, dried in a dryer set at a temperature of 150 ° C., and strontium zirconate. Obtained particles.

Example 2
(Manufacture of barium zirconate particles)
Step (a)
45.82 g of the wet cake of zirconium hydroxide obtained in Production Example 1 was dispensed into a plastic container having a capacity of 300 mL, and 5.49 g of barium hydroxide octahydrate (Fuji Film Wako Pure Chemical Industries, Ltd.) was further added thereto. , 0.83 g of barium zirconate seed crystal obtained in Production Example 3, 50 mL of ion-exchanged water and 30 mL of zirconia beads having a diameter of 0.5 mm were added to obtain a first slurry.

Step (b)
The plastic container was placed in a planetary ball mill (P-5 manufactured by Fritsch) and operated at a rotation speed of 210 rpm for 30 minutes to wet-pulverize the first slurry. The beads were removed from the obtained slurry by a sieve to obtain a slurry, and this slurry was transferred to a titanium container. Thus, a second slurry containing a particulate solid having an average particle diameter of 0.28 μm was obtained.

Step (c)
Subsequently, 13.44 g of barium hydroxide octahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 0.1 L of ion-exchanged water were added to the titanium container, and the mixture was stirred to generate water heat as a third slurry. A slurry before the reaction was obtained.

Step (d)
The titanium container containing the third slurry before the hydrothermal reaction was placed in an autoclave as it was, heated at 200 ° C. for 2 hours, and hydrothermally reacted to obtain a fourth slurry.

Process (e)
The fourth slurry was transferred to a polyethylene beaker equipped with a stirrer, a 0.2% aqueous nitric acid solution was added to adjust the pH of the slurry to 8, and the mixture was stirred as it was for 30 minutes. At this time, since the pH of the slurry increased, the pH was readjusted to 8 by adding a 0.2% nitric acid aqueous solution to the slurry again.

After that, the slurry is filtered, and the obtained solid matter is washed with ion-exchanged water until the electrical conductivity of the filtrate becomes 3 ms / m or less, dried in a dryer set at a temperature of 150 ° C., and barium zirconate. Obtained particles.

Example 3
Barium zirconate particles were obtained in the same manner as in Example 2 except that the amount of barium zirconate seed crystals used in step (a) of Example 2 was changed to 0.08 g.

Example 4
Barium zirconate particles were obtained in the same manner as in Example 2 except that the amount of barium zirconate seed crystals used in step (a) of Example 2 was changed to 0.41 g.

Example 5
Barium zirconate particles were obtained in the same manner as in Example 2 except that the amount of barium zirconate seed crystals used in step (a) of Example 2 was changed to 1.24 g.

Example 6
Barium zirconate particles were obtained in the same manner as in Example 2 except that the temperature of the hydrothermal reaction was changed to 180 ° C. in the step (d) of Example 2.

Example 7
Barium zirconate particles were obtained in the same manner as in Example 2 except that the temperature of the hydrothermal reaction was changed to 230 ° C. in the step (d) of Example 2.

Example 8
Except that 0.95 g of barium hydroxide octahydrate was used in the step (a) of Example 2 and 17.98 barium hydroxide octahydrate was used in the step (c) of Example 2. Barium zirconate particles were obtained in the same manner as in Example 2.

Example 9
Except that 9.46 g of barium hydroxide octahydrate was used in the step (a) of Example 2 and 9.46 g of barium hydroxide octahydrate was used in the step (c) of Example 2. Barium zirconate particles were obtained in the same manner as in Example 2.

Example 10
In the step (b) of the second embodiment, the slurry obtained in the step (a) of the second embodiment was wet-ground by using a planetary ball mill (P-5 manufactured by Fritsch) at a rotation speed of 210 rpm for 5 minutes. Barium zirconate particles were obtained in the same manner as in Example 2.

Comparative Example 1
Step (a)
45.82 g of the wet cake of zirconium hydroxide obtained in Production Example 1 was dispensed into a plastic container having a capacity of 300 mL, and 5.49 g of barium hydroxide octahydrate (Fuji Film Wako Pure Chemical Industries, Ltd.) was further added thereto. , 50 mL of ion-exchanged water and 30 mL of zirconia beads having a diameter of 0.5 mm were added to obtain a first slurry.

Step (b)
The plastic container was placed in a planetary ball mill (P-5 manufactured by Fritsch) and operated at a rotation speed of 210 rpm for 30 minutes to wet-pulverize the first slurry. The beads were removed from the obtained slurry by a sieve to obtain a slurry, and this slurry was transferred to a titanium container. Thus, a second slurry containing a particulate solid having an average particle diameter of 0.13 μm was obtained.

Step (c)
Subsequently, 13.44 g of barium hydroxide octahydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 0.1 L of ion-exchanged water were added to the titanium container, and the mixture was stirred to generate water heat as a third slurry. A slurry before the reaction was obtained.

Step (d)
The titanium container containing the third slurry before the hydrothermal reaction was placed in an autoclave as it was, heated at 200 ° C. for 2 hours, and hydrothermally reacted to obtain a fourth slurry.

Process (e)
The fourth slurry was transferred to a polyethylene beaker equipped with a stirrer, a 0.2% aqueous nitric acid solution was added to adjust the pH of the slurry to 8, and the mixture was stirred as it was for 30 minutes. At this time, since the pH of the slurry increased, the pH was readjusted to 8 by adding a 0.2% nitric acid aqueous solution to the slurry again.

After that, the slurry is filtered, and the obtained solid matter is washed with ion-exchanged water until the electrical conductivity of the filtrate becomes 3 ms / m or less, dried in a dryer set at a temperature of 150 ° C., and barium zirconate. Obtained particles.

Comparative Example 2
In the step (b) of the second embodiment, the slurry obtained in the step (a) of the second embodiment was wet-ground by running a planetary ball mill (P-5 manufactured by Fritsch) at a rotation speed of 150 rpm for 4 minutes. Barium zirconate particles were obtained in the same manner as in Example 2.

Comparative Example 3
(Production of strontium zirconate particles by solid phase method)
84.91 g of strontium carbonate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 70.93 g of zirconium oxide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 235 mL of ion-exchanged water, 3 g of dispersant, and zirconia beads having a diameter of 0.5 mm. 150 mL was placed in a plastic container having a capacity of 500 mL, placed in a planetary ball mill (P-5 manufactured by Fritsch), and wet pulverized at a rotation speed of 210 rpm until the average particle size became 0.6 μm or less to obtain a slurry. The beads were removed from the obtained slurry by a sieve, the slurry was dried in a dryer set at a temperature of 150 ° C. for 10 hours, and then pulverized with a sample mill (SK-10, manufactured by Kyoritsu Riko Co., Ltd.). Obtained powder. The obtained powder is filled in an alumina crucible, the crucible is placed in an electric furnace (HT16 / 17 manufactured by Chugai Engineering Co., Ltd.), the temperature is raised to 1400 ° C. at 200 ° C./hour in an atmospheric atmosphere furnace, and then 1400 ° C. After that, the temperature was lowered at 200 ° C./hour. The obtained fired product was pulverized with the above sample mill to obtain a powder.

150 g of the obtained powder, 230 mL of ion-exchanged water and 150 mL of zirconia beads having a diameter of 0.5 mm were placed in a plastic container having a capacity of 500 mL, placed in a planetary ball mill (P-5 manufactured by Fritsch), and rotated at 210 rpm for 30 minutes. Wet pulverized. The beads are removed by a sieve, the slurry is dried in a dryer set at a temperature of 150 ° C. for 10 hours, and then pulverized with a sample mill (SK-10, manufactured by Kyoritsu Riko Co., Ltd.) to obtain strontium zirconate particles. Obtained.

Comparative Example 4
(Manufacture of barium zirconate particles by solid phase method)
Barium carbonate 93.22 g (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and zirconium oxide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) 58.19 g, 230 mL of ion-exchanged water, 3 g of dispersant, and zirconia beads with a diameter of 0.5 mm. 150 mL was placed in a plastic container having a capacity of 500 mL, placed in a planetary ball mill (P-5 manufactured by Fritsch), and wet pulverized at a rotation speed of 210 rpm until the average particle size became 0.6 μm or less to obtain a slurry. The beads were removed from the slurry by a sieve, and the obtained slurry was dried in a dryer set at a temperature of 150 ° C. for 10 hours, and then pulverized with a sample mill (SK-10, manufactured by Kyoritsu Riko Co., Ltd.). Obtained powder.

The obtained powder is filled in an alumina crucible, the crucible is placed in an electric furnace (HT16 / 17 manufactured by Chugai Engineering Co., Ltd.), the temperature is raised to 1400 ° C. at 200 ° C./hour in an atmospheric atmosphere furnace, and then 1400 ° C. After that, the temperature was lowered at 200 ° C./hour. The obtained fired product was pulverized with the above sample mill to obtain a powder.

150 g of the obtained powder, 230 mL of ion-exchanged water and 150 mL of zirconia beads having a diameter of 0.5 mm were placed in a plastic container having a capacity of 500 mL to obtain a slurry.

The plastic container was placed in a planetary ball mill (P-5 manufactured by Fritsch) and wet pulverized at a rotation speed of 210 rpm for 30 minutes. The beads were removed by a sieve, and the obtained slurry was dried in a dryer set at a temperature of 150 ° C. for 10 hours, and then pulverized with a sample mill (SK-10, manufactured by Kyoritsu Riko Co., Ltd.) to obtain zirconate tit. Barium particles were obtained.

Comparative Example 5
Barium zirconate particles in the same manner as in Example 2 except that 9.46 g of barium hydroxide octahydrate was used in step (a) of Example 2 and step (c) of Example 2 was omitted. Got

Tables 1 and 2 show the reaction conditions for producing the zirconate-based perovskite-type composite oxide particles in the above Examples and Comparative Examples, and the physical properties of the obtained zirconate-based perovskite-type composite oxide particles. In addition, the physical characteristics of strontium zirconate and barium zirconate obtained in Production Examples 2 and 3 are also shown. Further, the dielectric constants of the zirconate-based perovskite-type composite oxide particles obtained in some of Examples and Comparative Examples are shown.

In Tables 1 and 2, the amount of the seed crystal of barium zirconate or strontium zirconate used in the step (a) is the amount of zirconium in the zirconium hydroxide contained in the first slurry in the step (a), respectively. The number of moles is the number of moles with respect to 100 moles.

Further, the finally obtained zirconate-based perovskite-type composite oxide particles contain seed crystals, and therefore, the A / B molar ratio of the obtained zirconate-based perovskite-type composite oxide particles is the composition ratio including the seed crystals. Is.

According to Examples 1 to 10, when preparing a first slurry containing a raw material mixture composed of barium hydroxide or strontium hydroxide and zirconium hydroxide in step (a), the first slurry is prepared. A seed crystal of barium zirconate or strontium zirconate is present in the slurry, and in step (b), the first slurry containing the raw material mixture is wet-ground and particles having a predetermined average particle size determined in advance. A second slurry containing a solid substance is obtained, and in step (c), barium hydroxide or strontium barium hydroxide is newly added to the second slurry to provide a third slurry containing an excess of barium or strontium. In step (d), the third slurry was subjected to a hydrothermal reaction, and then in step (e), the fourth slurry obtained by the hydrothermal reaction was acid-treated and then washed with water. By removing excess barium or strontium, the specific surface area is 10 m ² / g or more, is fine, and the crystallite size / specific surface area equivalent particle size is in the range of 0.7 to 1.3. Therefore, it is possible to obtain highly crystalline zirconic acid-based perovskite-type composite oxide particles that are close to 1, that is, close to a single crystal.

Further, in the products according to Examples 1 to 10, the XRD pattern was qualitatively analyzed using X-ray analysis software (PDXL2.7) manufactured by Rigaku Co., Ltd., and the crystal phase was identified. As a result, zirconate tit was used. Since it was consistent with barium (BaZrO ₃ ) (PDF number 00-006-0399) or strontium zirconate (SrZrO ₃ ) (PDF number 01-074-2231), it was confirmed to be monophasic.

In Comparative Example 1, since the seed crystal of barium zirconate was not used in the preparation of the raw material mixture in the step (a), fine barium titanate particles could not be obtained, and the obtained barium zirconate was obtained. The particles had a small crystallite size / specific surface area conversion particle size and low crystallinity.

In Comparative Example 2, the wet pulverization of the slurry in the step (b) was not sufficient, and the average particle size of the particulate solid could not be made equal to or less than a predetermined value. Therefore, fine barium zirconate particles were obtained. I couldn't. Moreover, the obtained barium zirconate particles had low crystallinity.

Comparative Example 3 shows the physical properties of the strontium zirconate particles obtained by the solid-phase method, and Comparative Example 4 shows the physical properties of the barium dilconate particles obtained by the solid-phase method. In each case, the specific surface area was small and the crystallinity was low.

In Comparative Example 5, in step (c), the slurry was subjected to a hydrothermal reaction with the A / B molar ratio of 1.00 without adding the hydroxide of the element A to the second slurry. The obtained barium zirconate had a too small A / B molar ratio and a large specific surface area, but low crystallinity.

Production Example 2 shows the physical characteristics of the seed crystal of strontium zirconate, and Production Example 3 shows the physical characteristics of the seed crystal of barium dilconate.

Claims (4)

Composition formula (I)
AB _x O _3-δ
(In the formula, A is at least one element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9 ≦ x ≦ 1.1, and δ is oxygen. The amount of deficiency.)
A method for producing zirconate-based perovskite-type composite oxide particles represented by.
(A) A step of mixing a hydroxide of element A, a zirconium hydroxide, and a seed crystal of a zirconic acid-based perovskite-type composite oxide containing the element A with water to obtain a first slurry.
(B) A step of wet-pulverizing the first slurry to obtain a second slurry containing a particulate solid having an average particle diameter of 2.0 μm or less.
(C) A step of adding a hydroxide of element A to the second slurry to obtain a third slurry.
(D) The step of hydrothermally reacting the third slurry to obtain a fourth slurry, and (e) the fourth slurry is acid-treated and then washed with water to obtain excess water of the element A. Including the step of removing oxides
In the above step (a), the A / B molar ratio of the first slurry is set to 0.1 or more.
In the above step (c), the A / B molar ratio of the third slurry is set to 1.2 or more.
A method for producing zirconate-based perovskite-type composite oxide particles. The zirconate titer according to claim 1, wherein in the step (a), the seed crystal is used in the range of 1 to 20 mol parts with respect to 100 mol parts of zirconium in the zirconium hydroxide contained in the first slurry. A method for producing acid-based perovskite-type composite oxide particles. The method for producing zirconate-based perovskite-type composite oxide particles according to claim 1, wherein the hydrothermal reaction is carried out in a temperature range of 120 to 300 ° C. Composition formula (I)
AB _x O _3-δ
(In the formula, A is at least one element selected from the group consisting of Ba and Sr, B is a Zr element, x is a number satisfying 0.9 ≦ x ≦ 1.1, and δ is oxygen. The amount of deficiency.)
Zirconic acid-based perovskite-type composite oxide particles having a specific surface area of 12 m ² / g or more and a crystallite diameter / specific surface area equivalent particle diameter in the range of 0.7 to 1.3.