WO2015152237A1 - Strontium titanate fine particle powder and method for producing same - Google Patents

Strontium titanate fine particle powder and method for producing same Download PDF

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WO2015152237A1
WO2015152237A1 PCT/JP2015/060115 JP2015060115W WO2015152237A1 WO 2015152237 A1 WO2015152237 A1 WO 2015152237A1 JP 2015060115 W JP2015060115 W JP 2015060115W WO 2015152237 A1 WO2015152237 A1 WO 2015152237A1
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strontium titanate
strontium
fine particle
titanate fine
particle powder
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PCT/JP2015/060115
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French (fr)
Japanese (ja)
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誉元 河口
英知 宇根本
竜次 藤田
晴己 黒川
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戸田工業株式会社
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Priority to JP2016511930A priority Critical patent/JP6583637B2/en
Publication of WO2015152237A1 publication Critical patent/WO2015152237A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/003—Titanates
    • C01G23/006—Alkaline earth titanates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • B01J35/30—
    • B01J35/39—
    • B01J35/40—
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/30—Three-dimensional structures
    • C01P2002/34—Three-dimensional structures perovskite-type (ABO3)
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/85—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by XPS, EDX or EDAX data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the object of the present invention is to obtain spherical strontium titanate fine particles having excellent dispersibility.
  • strontium titanate fine particle powder of a perovskite compound that has a relatively high dielectric constant and does not have a Curie point is widely used in temperature-proof ceramic capacitors. It is required to have good distribution, no aggregation, excellent dispersibility, and high packing density.
  • strontium titanate is used for various applications by utilizing various characteristics of strontium titanate.
  • a point having a high refractive index it is used for optical applications such as pigments, reflectors and light collectors, and is used for a visible light photocatalyst using a point having photocatalytic activity.
  • Patent Documents 1 to 4 Conventionally, various studies have been made on strontium titanate (Patent Documents 1 to 4).
  • JP 2003-277054 A JP-A-6-48734 JP-A-5-58633 JP 59-45828
  • strontium titanate fine particle powder satisfying the above-mentioned properties is currently most demanded, but has not yet been obtained.
  • Patent Document 1 strontium titanate fine particles having a rectangular parallelepiped shape are described.
  • the particle shape is a rectangular parallelepiped shape, it is difficult to increase the packing density.
  • Patent Document 2 described above describes a method for producing a strontium titanate fine particle powder having an average particle size of 0.05 ⁇ m or less, but the particle size of the obtained strontium titanate is small for ceramic capacitor use, Further, improvement of dispersibility is not taken into consideration. Furthermore, in this method, an in-line mixer is required to mix the reaction instantaneously and uniformly, and the process becomes complicated and it is difficult to say that it is industrially preferable.
  • Patent Document 3 described above describes a production method in which a hydrolyzate of a titanium compound and a strontium compound are wet-reacted in the presence of hydrogen peroxide to obtain strontium titanate.
  • the strontium titanate shown has a large average particle size of 0.2 ⁇ m or more, and this method is uneconomical because of the large amount of hydrogen peroxide used.
  • Patent Document 4 describes that a hydrolysis product of a titanium compound and a water-soluble strontium salt are reacted in a strong alkaline aqueous solution to obtain ultrafine strontium titanate. Has a particle diameter that is too small for ceramic capacitor applications.
  • a technical problem of the present invention is to produce a spherical strontium titanate fine particle powder that is fine and excellent in dispersibility economically and industrially advantageously.
  • the present invention is a cubic strontium titanate fine particle powder characterized in that it is cubic strontium titanate, wherein the primary particles have an average primary particle diameter of 50 to 150 nm and a sphericity of 0.8 or more. There is (Invention 1).
  • the present invention is the strontium titanate fine particle powder according to the first aspect of the present invention, and the strontium titanate fine particle powder having a crystallite size of 200 mm or more (Invention 2).
  • the present invention also provides a wet reaction in a temperature range of 60 to 200 ° C. by heating a hydrous titanium hydroxide slurry obtained by neutralizing a titanium tetrachloride aqueous solution with a strontium hydroxide aqueous solution and then adding the strontium hydroxide aqueous solution.
  • a method for producing a strontium titanate fine particle powder according to the first or second aspect of the present invention (Invention 3).
  • the strontium titanate fine particles according to the present invention are fine and spherical particles, the packing density can be increased. Further, the strontium titanate fine particle powder according to the present invention is excellent in dispersibility since aggregation is suppressed.
  • the strontium titanate fine particle powder according to the present invention is cubic and has an average primary particle diameter of primary particles of 50 to 150 nm and a sphericity of 0.8 or more.
  • the average primary particle diameter of the primary particles of the strontium titanate fine particle powder according to the present invention is 50 to 150 nm. By controlling the average primary particle diameter within the above range, a strontium titanate fine particle powder having excellent dispersibility can be obtained.
  • a preferable average primary particle diameter is 50 to 120 nm, and more preferably 50 to 100 nm.
  • the strontium titanate fine particle powder according to the present invention is cubic.
  • the strontium titanate fine particle powder according to the present invention is spherical, and its sphericity is 0.8 or more.
  • the strontium titanate fine particles have a sphericity of less than 0.8, the shape is a rectangular parallelepiped and the packing density is lowered.
  • the sphericity is preferably 0.82 or more, more preferably 0.83 to 1.0. The sphericity is evaluated by the method described later.
  • the strontium titanate fine particle powder according to the present invention preferably has a crystallite size of 200 mm or more. If the crystallite size is less than 200 mm, the particles having an average particle diameter of 50 nm or more are close to polycrystals, so that the crystallinity is lowered. A more preferable crystallite size is 220 to 500 mm.
  • the lattice constant of the strontium titanate fine particle powder according to the present invention is preferably 3.900 to 3.950 ⁇ . When the lattice constant is within the above range, it can be identified as strontium titanate.
  • the BET specific surface area of the strontium titanate fine particle powder according to the present invention is preferably 15.0 to 50.0 m 2 / g.
  • the average particle diameter of the strontium titanate fine particle powder is larger than 150 nm.
  • the strontium titanate fine particle powder having a specific surface area value exceeding 50.0 m 2 / g has an average particle size of less than 50 nm.
  • a more preferred BET specific surface area is 15.0 to 45.0 m 2 / g.
  • the primary particle diameter (D50) with respect to the particle size distribution of the strontium titanate fine particle powder according to the present invention is preferably 50 to 150 nm. By controlling the primary particle size of the particle size distribution within the above range, it is possible to obtain a strontium titanate fine particle powder having excellent dispersibility. A more preferable primary particle diameter (D50) is 50 to 120 nm.
  • the strontium titanate fine particle powder according to the present invention is obtained by neutralizing a titanium tetrachloride aqueous solution with a strontium hydroxide aqueous solution to obtain a hydrous titanium hydroxide slurry (neutralization reaction), and adding the strontium hydroxide aqueous solution to the hydrous titanium hydroxide slurry. It can be obtained by addition and wet reaction in the temperature range of 60 to 200 ° C. That is, in the present invention, a titanium tetrachloride aqueous solution and a strontium hydroxide aqueous solution are mixed to divide the reaction into two stages to obtain a hydrous titanium hydroxide slurry.
  • the reaction for obtaining seed particles in the former stage is a neutralization reaction, and the reaction in the latter stage.
  • the reaction to complete the target strontium titanate particles is defined as a wet reaction for convenience.
  • the addition ratio (Sr / Ti) of the titanium raw material and the alkaline aqueous solution during the neutralization reaction is preferably 1.4 to 1.8.
  • the addition ratio is less than 1.4, the production yield of strontium titanate core particles decreases, and when it exceeds 1.8, the distribution of primary particles of strontium titanate deteriorates.
  • a more preferable addition ratio is 1.45 to 1.75.
  • the temperature range of the neutralization reaction is not particularly limited, but is preferably about room temperature to 50 ° C.
  • reaction solution After performing the neutralization reaction, the reaction solution is heated to 60 ° C. or higher, and then an aqueous strontium hydroxide solution is added (wet reaction).
  • the addition ratio of strontium hydroxide in the wet reaction is preferably 0.7 to 2.3 with respect to Ti in the reaction solution.
  • the addition ratio is less than 0.7, the growth reaction of strontium titanate is not sufficient, and the production yield decreases.
  • the addition ratio exceeds 2.3 the amount of strontium hydroxide in the reaction solution exceeds the solubility. Therefore, strontium hydroxide precipitates and it is difficult to perform a uniform liquid phase reaction.
  • a more preferable addition ratio is 1.0 to 2.0.
  • the pH of the reaction solution is preferably 11 to 13.5.
  • the addition ratio of strontium hydroxide in the wet reaction is preferably 0.5 to 1.2 with respect to strontium hydroxide added in the neutralization reaction.
  • the addition ratio is less than 0.5, the reaction for producing strontium titanate is not sufficient and unreacted substances remain, and when it exceeds 1.2, the amount of strontium hydroxide in the reaction solution exceeds the solubility. Strontium hydroxide precipitates and it is difficult to perform a uniform liquid phase reaction.
  • a more preferable addition ratio is 0.55 to 1.0 with respect to strontium hydroxide added in the neutralization reaction.
  • the reaction concentration of the reaction solution for producing strontium titanate fine particles is preferably 0.05 to 0.7 mol / L in terms of titanium compound. If it is less than 0.05 mol / L, the yield is low and not industrial, and if it is 0.7 mol / L or more, the amount of strontium hydroxide in the reaction solution exceeds the solubility, so Sr (OH) 2 is precipitated, It is difficult to perform a uniform liquid phase reaction.
  • the reaction temperature of the wet reaction is preferably 60 to 250 ° C. When the temperature is less than 60 ° C., it is difficult to obtain dense spherical strontium titanate fine particles. When it exceeds 250 ° C., it is difficult to design a hydrothermal container. Preferably, it is 65 to 190 ° C.
  • the temperature at which the aqueous strontium hydroxide solution is added and the temperature at which the reaction is performed thereafter may be the same or different.
  • the particles after the wet reaction are washed with water and dried according to a conventional method. Excess strontium can be washed away by washing with water. In addition, impurities such as Na, K, and Cl can be removed at the same time.
  • pulverization / disintegration treatment may be performed.
  • the strontium titanate fine particle powder of the present invention obtained by the above method is excellent in dispersibility. That is, since there are few secondary particles by aggregation, the difference of an average primary particle diameter and a primary particle diameter (D50) is small.
  • the dispersibility evaluated by the following formula is preferably 5% or less, more preferably 2% or less. ⁇ (Primary particle diameter (D50) ⁇ Average primary particle diameter) / Average primary particle diameter ⁇ ⁇ 100 (%)
  • a typical embodiment of the present invention is as follows.
  • the average primary particle diameter is a particle diameter obtained by setting the diameter of a circle having an area equivalent to the area obtained from the photograph for each particle as the particle diameter and averaging the diameter for all the measured particles.
  • D50 is a particle diameter at which the cumulative ratio is 50% when the number of measured particles is 100% and the cumulative ratio with respect to the particle diameter is determined.
  • the particle shape was determined from the electron micrograph. Further, the sphericity was indicated by (4 ⁇ ⁇ area) / (2 ⁇ perimeter) of particles measured from the electron micrograph.
  • the crystal structure was measured using an “X-ray diffractometer SmartLab” (manufactured by Rigaku Denki Kogyo Co., Ltd.) (tube: Cu), and 2 ⁇ was measured in the range of 10 to 90 °, and the lattice constant was determined using the WPPF method. Calculated.
  • the crystallite size was calculated using the Halder-Wagner method.
  • the specific surface area value is a value measured by the BET method.
  • the dispersibility of the strontium titanate fine particle powder was evaluated by the following formula from the average primary particle size and the primary particle size (D50) of the particle size distribution obtained above. ⁇ (Primary particle diameter (D50) ⁇ Average primary particle diameter) / Average primary particle diameter ⁇ ⁇ 100 (%)
  • Example 1 A titanium tetrachloride aqueous solution having a Ti molar concentration of 1.35 mol / l was prepared, and a 20 wt% strontium hydroxide aqueous solution was added thereto so that the Sr / Ti molar ratio was 1.45 to obtain a titanium hydroxide slurry. (Neutralization reaction). The slurry was put into a reaction vessel purged with nitrogen and heated to 90 ° C. with stirring, and then a 20 wt% strontium hydroxide aqueous solution was added so that the molar ratio of Sr / Ti was 1.2.
  • the strontium hydroxide added by the wet reaction was 0.83 in molar ratio with respect to the strontium hydroxide used in the neutralization reaction. Thereafter, stirring was continued at 90 ° C. for 3 hours to complete the reaction. After the reaction, the reaction mixture was cooled to room temperature, washed with Nutsche until the filtrate had an electric conductivity of 500 ⁇ S / cm, filtered and dried to obtain white powder of cubic strontium titanate fine particles.
  • the obtained strontium titanate fine particle powder is observed with an electron microscope, it is a spherical particle having a primary average particle diameter of 52.6 nm and a sphericity of 0.86, and a crystallite size of 245 mm from a powder X-ray diffraction measurement. It was confirmed to be a single phase.
  • Examples 2 to 6 and Comparative Example 1 Strontium titanate fine particle powder was obtained in the same manner as in Example 1 except that the reaction concentration, the amount of strontium hydroxide during neutralization and crystallization, the reaction temperature, and the time were changed. In addition, Example 4 was performed in the hydrothermal container.
  • the strontium titanates obtained in Examples 1 to 6 are excellent in dispersibility.
  • Comparative Example 1 in which strontium titanate was obtained in one step without performing the neutralization reaction the difference between the average primary particle size and the primary particle size (D50) was large, and the influence of the aggregated particles was recognized, and the dispersibility was improved. Not good.
  • the strontium titanate fine particle powder according to the present invention is characterized in that the average particle diameter can be controlled according to the purpose, and the packing density is easily increased because it is highly crystalline and spherical. Therefore, the strontium titanate fine particle powder of the present invention is most suitable for use in electronic parts such as ceramic capacitors, optical use such as a reflecting material and a light collecting material, a catalyst and a thermoelectric material.

Abstract

The present invention relates to a strontium titanate fine particle powder that is a cubic strontium titanate and is characterized in that the average primary particle size of primary particles is 50-150 nm and the sphericity is at least 0.8. Said cubic strontium titanate can be obtained by heating a hydrated titanium hydroxide slurry obtained by neutralizing a titanium tetrachloride aqueous solution in a hydrated strontium aqueous solution, then adding the hydrated strontium aqueous solution and inducing a wet reaction at a temperature range of 60-200 °C. This spherical strontium titanate fine particle powder has excellent dispersibility.

Description

チタン酸ストロンチウム微粒子粉末及びその製造方法Strontium titanate fine particle powder and method for producing the same
　本発明は、分散性に優れた球状チタン酸ストロンチウム微粒子粉末を得ることを目的とするものである。 The object of the present invention is to obtain spherical strontium titanate fine particles having excellent dispersibility.
　近年、各種電子機器の小型化、高性能化及び軽量化に伴い、電子機器部品、例えばセラミックコンデンサなどの誘電材料に用いられるチタン酸ストロンチウム微粒子粉末についても特性改善が要求されている。 In recent years, with the reduction in size, performance and weight of various electronic devices, there is a demand for improvement in characteristics of strontium titanate fine particle powder used for dielectric materials such as electronic device parts, for example, ceramic capacitors.
　周知の通り、温度保障用セラミックコンデンサには比較的高い誘電率を有しキュリー点が存在しないペロブスカイト化合物のチタン酸ストロンチウム微粒子粉末が多用されており、コンデンサに用いられるチタン酸ストロンチウム微粒子粉末は、粒度分布が良く凝集がなく分散性に優れかつ充填密度が高いことが要求されている。 As is well known, strontium titanate fine particle powder of a perovskite compound that has a relatively high dielectric constant and does not have a Curie point is widely used in temperature-proof ceramic capacitors. It is required to have good distribution, no aggregation, excellent dispersibility, and high packing density.
　また、チタン酸ストロンチウムの種々の特性を利用して種々の用途に用いられている。例えば、高い屈折率を有する点を利用して、顔料や、反射材並びに集光材等の光学用途に用いられ、光触媒活性を有する点を利用して可視光光触媒に用いられたり、さらに、他の元素を添加して半導体化する点などを利用して、半導体、半導体コンデンサ、熱電材料、ＥＬ、発光材料などに用いられる。 Also, it is used for various applications by utilizing various characteristics of strontium titanate. For example, using a point having a high refractive index, it is used for optical applications such as pigments, reflectors and light collectors, and is used for a visible light photocatalyst using a point having photocatalytic activity. It is used for a semiconductor, a semiconductor capacitor, a thermoelectric material, an EL, a light emitting material, etc. by utilizing the point that a semiconductor is formed by adding this element.
　前述した種々の用途においても、微細であって充填密度の上がりやすい形状をしていることが要求されている。 Also in the various uses described above, it is required to have a fine shape that can easily increase the packing density.
　従来より、チタン酸ストロンチウムについて種々の検討がなされている（特許文献１～４）。 Conventionally, various studies have been made on strontium titanate (Patent Documents 1 to 4).
特開２００３－２７７０５４号公報JP 2003-277054 A 特開平６－４８７３４号公報JP-A-6-48734 特開平５－５８６３３号公報JP-A-5-58633 特開昭５９－４５９２８号公報JP 59-45828
　前記諸特性を満たすチタン酸ストロンチウム微粒子粉末は現在最も要求されているところであるが、未だ得られていない。 The strontium titanate fine particle powder satisfying the above-mentioned properties is currently most demanded, but has not yet been obtained.
　即ち、前出特許文献１には、直方体状粒子のチタン酸ストロンチウム微粒子が記載されているが、粒子形状が直方体状であるため充填密度を上げることは困難である。 That is, in Patent Document 1 described above, strontium titanate fine particles having a rectangular parallelepiped shape are described. However, since the particle shape is a rectangular parallelepiped shape, it is difficult to increase the packing density.
　また、前出特許文献２には、平均粒子径が０．０５μｍ以下のチタン酸ストロンチウム微粒子粉末の製造方法が記載されているが、得られるチタン酸ストロンチウムの粒子径はセラミックコンデンサ用途としても小さく、また分散性の向上については考慮されていない。更にこの方法では反応を瞬間的かつ均一に混合するためにインラインミキサーが必要となり、工程が複雑なものとなって工業的に好ましいとは言い難いものである。 In addition, Patent Document 2 described above describes a method for producing a strontium titanate fine particle powder having an average particle size of 0.05 μm or less, but the particle size of the obtained strontium titanate is small for ceramic capacitor use, Further, improvement of dispersibility is not taken into consideration. Furthermore, in this method, an in-line mixer is required to mix the reaction instantaneously and uniformly, and the process becomes complicated and it is difficult to say that it is industrially preferable.
　また、前出特許文献３には、チタン化合物の加水分解物とストロンチウム化合物とを過酸化水素の存在下で湿式反応させて、チタン酸ストロンチウムを得る製造方法が記載されているが、実施例で示されたチタン酸ストロンチウムも平均粒子径は０．２μｍ以上と大きいものであり、またこの方法では過酸化水素の使用量が多いため不経済である。 In addition, Patent Document 3 described above describes a production method in which a hydrolyzate of a titanium compound and a strontium compound are wet-reacted in the presence of hydrogen peroxide to obtain strontium titanate. The strontium titanate shown has a large average particle size of 0.2 μm or more, and this method is uneconomical because of the large amount of hydrogen peroxide used.
　また、前出特許文献４には、チタン化合物の加水分解生成物と水溶性ストロンチウム塩とを強アルカリ水溶液中で反応させて超微粒子のチタン酸ストロンチウムを得ることが記載されているが、粒子径は１００～２００Åでありセラミックコンデンサ用途としては粒子径が小さすぎるものである。 In addition, the aforementioned Patent Document 4 describes that a hydrolysis product of a titanium compound and a water-soluble strontium salt are reacted in a strong alkaline aqueous solution to obtain ultrafine strontium titanate. Has a particle diameter that is too small for ceramic capacitor applications.
　そこで、本発明は、微細で分散性に優れている球状チタン酸ストロンチウム微粒子粉末を経済的、且つ工業的に有利に製造することを技術的課題とする。 Therefore, a technical problem of the present invention is to produce a spherical strontium titanate fine particle powder that is fine and excellent in dispersibility economically and industrially advantageously.
　前記目的は、次の通りの本発明によって達成できる。 The above object can be achieved by the present invention as follows.
　即ち、本発明は、立方晶系チタン酸ストロンチウムであって、一次粒子の平均一次粒子径が５０～１５０ｎｍであって球形度が０．８以上であることを特徴とするチタン酸ストロンチウム微粒子粉末である（本発明１）。 That is, the present invention is a cubic strontium titanate fine particle powder characterized in that it is cubic strontium titanate, wherein the primary particles have an average primary particle diameter of 50 to 150 nm and a sphericity of 0.8 or more. There is (Invention 1).
　また、本発明は、本発明１記載のチタン酸ストロンチウム微粒子粉末であって、結晶子サイズが２００Å以上であるチタン酸ストロンチウム微粒子粉末である（本発明２）。 Further, the present invention is the strontium titanate fine particle powder according to the first aspect of the present invention, and the strontium titanate fine particle powder having a crystallite size of 200 mm or more (Invention 2).
　また、本発明は、四塩化チタン水溶液を水酸化ストロンチウム水溶液で中和することで得た含水水酸化チタンスラリーを加熱した後、水酸化ストロンチウム水溶液を添加し６０～２００℃の温度範囲で湿式反応させることを特徴とする本発明１又は２に記載のチタン酸ストロンチウム微粒子粉末の製造方法である（本発明３）。 The present invention also provides a wet reaction in a temperature range of 60 to 200 ° C. by heating a hydrous titanium hydroxide slurry obtained by neutralizing a titanium tetrachloride aqueous solution with a strontium hydroxide aqueous solution and then adding the strontium hydroxide aqueous solution. A method for producing a strontium titanate fine particle powder according to the first or second aspect of the present invention (Invention 3).
　本発明に係るチタン酸ストロンチウム微粒子粉末は、微細で球状粒子であるので、充填密度を上げることができる。また、本発明に係るチタン酸ストロンチウム微粒子粉末は、凝集が抑制されているので、分散性に優れている。 Since the strontium titanate fine particles according to the present invention are fine and spherical particles, the packing density can be increased. Further, the strontium titanate fine particle powder according to the present invention is excellent in dispersibility since aggregation is suppressed.
　本発明の構成を詳述すれば、次の通りである。 The configuration of the present invention will be described in detail as follows.
　本発明に係るチタン酸ストロンチウム微粒子粉末は、立方晶系であり、一次粒子の平均一次粒子径が５０～１５０ｎｍであって球形度が０．８以上である。 The strontium titanate fine particle powder according to the present invention is cubic and has an average primary particle diameter of primary particles of 50 to 150 nm and a sphericity of 0.8 or more.
　本発明に係るチタン酸ストロンチウム微粒子粉末の一次粒子の平均一次粒子径は５０～１５０ｎｍである。平均一次粒子径を前記範囲に制御することによって、分散性に優れたチタン酸ストロンチウム微粒子粉末とすることができる。好ましい平均一次粒子径は５０～１２０ｎｍであり、より好ましくは５０～１００ｎｍである。 The average primary particle diameter of the primary particles of the strontium titanate fine particle powder according to the present invention is 50 to 150 nm. By controlling the average primary particle diameter within the above range, a strontium titanate fine particle powder having excellent dispersibility can be obtained. A preferable average primary particle diameter is 50 to 120 nm, and more preferably 50 to 100 nm.
　本発明に係るチタン酸ストロンチウム微粒子粉末は立方晶系である。 The strontium titanate fine particle powder according to the present invention is cubic.
　本発明に係るチタン酸ストロンチウム微粒子粉末は球状であり、その球形度は０．８以上である。チタン酸ストロンチウム微粒子の球形度が０．８未満の場合、形状が直方体状などであり充填密度が低下する。好ましい球形度は０．８２以上であり、より好ましくは０．８３～１．０である。なお、球形度は後述する方法で評価する。 The strontium titanate fine particle powder according to the present invention is spherical, and its sphericity is 0.8 or more. When the strontium titanate fine particles have a sphericity of less than 0.8, the shape is a rectangular parallelepiped and the packing density is lowered. The sphericity is preferably 0.82 or more, more preferably 0.83 to 1.0. The sphericity is evaluated by the method described later.
　本発明に係るチタン酸ストロンチウム微粒子粉末は結晶子サイズが２００Å以上であることが好ましい。結晶子サイズが２００Å未満であると平均粒径が５０ｎｍ以上の粒子では粒子が多結晶に近くなるため結晶性が低下する。より好ましい結晶子サイズは２２０～５００Åである。 The strontium titanate fine particle powder according to the present invention preferably has a crystallite size of 200 mm or more. If the crystallite size is less than 200 mm, the particles having an average particle diameter of 50 nm or more are close to polycrystals, so that the crystallinity is lowered. A more preferable crystallite size is 220 to 500 mm.
　本発明に係るチタン酸ストロンチウム微粒子粉末の格子定数は、３．９００～３．９５０Åが好ましい。格子定数が前記範囲内にあることによって、チタン酸ストロンチウムであると同定できる。 The lattice constant of the strontium titanate fine particle powder according to the present invention is preferably 3.900 to 3.950 Å. When the lattice constant is within the above range, it can be identified as strontium titanate.
　本発明に係るチタン酸ストロンチウム微粒子粉末のＢＥＴ比表面積は１５．０～５０．０ｍ２／ｇが好ましい。ＢＥＴ比表面積が１５．０ｍ２／ｇ未満の場合には、チタン酸ストロンチウム微粒子粉末の平均粒子径が１５０ｎｍより大きくなる。また、比表面積値が５０．０ｍ２／ｇを超えるチタン酸ストロンチウム微粒子粉末は平均粒子径が５０ｎｍ未満となる。より好ましいＢＥＴ比表面積は１５．０～４５．０ｍ２／ｇである。 The BET specific surface area of the strontium titanate fine particle powder according to the present invention is preferably 15.0 to 50.0 m 2 / g. When the BET specific surface area is less than 15.0 m 2 / g, the average particle diameter of the strontium titanate fine particle powder is larger than 150 nm. In addition, the strontium titanate fine particle powder having a specific surface area value exceeding 50.0 m 2 / g has an average particle size of less than 50 nm. A more preferred BET specific surface area is 15.0 to 45.0 m 2 / g.
　本発明に係るチタン酸ストロンチウム微粒子粉末の粒度分布に対する一次粒子径（Ｄ５０）は５０～１５０ｎｍが好ましい。粒度分布の一次粒子径を前記範囲に制御することによって、分散性に優れたチタン酸ストロンチウム微粒子粉末とすることができる。より好ましい一次粒子径（Ｄ５０）は５０～１２０ｎｍである。 The primary particle diameter (D50) with respect to the particle size distribution of the strontium titanate fine particle powder according to the present invention is preferably 50 to 150 nm. By controlling the primary particle size of the particle size distribution within the above range, it is possible to obtain a strontium titanate fine particle powder having excellent dispersibility. A more preferable primary particle diameter (D50) is 50 to 120 nm.
　次に、本発明に係るチタン酸ストロンチウム微粒子粉末の製造法について述べる。 Next, a method for producing strontium titanate fine particles according to the present invention will be described.
　本発明に係るチタン酸ストロンチウム微粒子粉末は、四塩化チタン水溶液を水酸化ストロンチウム水溶液で中和して含水水酸化チタンスラリーを得（中和反応）、当該含水水酸化チタンスラリーに水酸化ストロンチウム水溶液を添加し６０～２００℃の温度範囲で湿式反応させて得ることができる。すなわち、本発明においては、四塩化チタン水溶液と水酸化ストロンチウム水溶液とを混合して含水水酸化チタンスラリーを得る反応２段階に分け、前段で種粒子を得る反応は中和反応、後段で反応を完結させて目的とするチタン酸ストロンチウム粒子を得る反応を湿式反応と便宜上規定する。 The strontium titanate fine particle powder according to the present invention is obtained by neutralizing a titanium tetrachloride aqueous solution with a strontium hydroxide aqueous solution to obtain a hydrous titanium hydroxide slurry (neutralization reaction), and adding the strontium hydroxide aqueous solution to the hydrous titanium hydroxide slurry. It can be obtained by addition and wet reaction in the temperature range of 60 to 200 ° C. That is, in the present invention, a titanium tetrachloride aqueous solution and a strontium hydroxide aqueous solution are mixed to divide the reaction into two stages to obtain a hydrous titanium hydroxide slurry. The reaction for obtaining seed particles in the former stage is a neutralization reaction, and the reaction in the latter stage. The reaction to complete the target strontium titanate particles is defined as a wet reaction for convenience.
　中和反応の際のチタン原料とアルカリ性水溶液との添加割合（Ｓｒ／Ｔｉ）は、１．４～１．８が好ましい。前記添加割合が１．４未満の場合にはチタン酸ストロンチウム核粒子の生成収率が低下し、１．８を越える場合には、チタン酸ストロンチウムの一次粒子の分布が悪化する。より好ましい添加割合は１．４５～１．７５である。
　中和反応の温度範囲は特に限定されるものではないが、室温から５０℃程度が好ましい。 The addition ratio (Sr / Ti) of the titanium raw material and the alkaline aqueous solution during the neutralization reaction is preferably 1.4 to 1.8. When the addition ratio is less than 1.4, the production yield of strontium titanate core particles decreases, and when it exceeds 1.8, the distribution of primary particles of strontium titanate deteriorates. A more preferable addition ratio is 1.45 to 1.75.
The temperature range of the neutralization reaction is not particularly limited, but is preferably about room temperature to 50 ° C.
　中和反応を行った後、反応溶液を６０℃以上に昇温した後、水酸化ストロンチウム水溶液を添加する（湿式反応）。 After performing the neutralization reaction, the reaction solution is heated to 60 ° C. or higher, and then an aqueous strontium hydroxide solution is added (wet reaction).
　湿式反応の際の水酸化ストロンチウムの添加割合は、反応溶液中のＴｉに対して０．７～２．３が好ましい。前記添加割合が０．７未満の場合にはチタン酸ストロンチウムの成長反応が十分ではなく生成収率が低下し、２．３を越える場合には、反応溶液中の水酸化ストロンチウム量が溶解度を超えるため、水酸化ストロンチウムが析出し、均一な液相反応を行うことが困難である。より好ましい添加割合は１．０～２．０である。反応溶液のｐＨは１１～１３．５が好ましい。 The addition ratio of strontium hydroxide in the wet reaction is preferably 0.7 to 2.3 with respect to Ti in the reaction solution. When the addition ratio is less than 0.7, the growth reaction of strontium titanate is not sufficient, and the production yield decreases. When the addition ratio exceeds 2.3, the amount of strontium hydroxide in the reaction solution exceeds the solubility. Therefore, strontium hydroxide precipitates and it is difficult to perform a uniform liquid phase reaction. A more preferable addition ratio is 1.0 to 2.0. The pH of the reaction solution is preferably 11 to 13.5.
　湿式反応の際の水酸化ストロンチウムの添加割合は、中和反応の際に添加した水酸化ストロンチウムに対して０．５～１．２が好ましい。添加割合が０．５未満の場合にはチタン酸ストロンチウムの生成反応が十分でなく未反応物が残り、１．２を超える場合には、反応溶液中の水酸化ストロンチウム量が溶解度を超えるため、水酸化ストロンチウムが析出し、均一な液相反応を行なうことが困難である。より好ましい添加割合は中和反応の際に添加した水酸化ストロンチウムに対して０．５５～１．０である。 The addition ratio of strontium hydroxide in the wet reaction is preferably 0.5 to 1.2 with respect to strontium hydroxide added in the neutralization reaction. When the addition ratio is less than 0.5, the reaction for producing strontium titanate is not sufficient and unreacted substances remain, and when it exceeds 1.2, the amount of strontium hydroxide in the reaction solution exceeds the solubility. Strontium hydroxide precipitates and it is difficult to perform a uniform liquid phase reaction. A more preferable addition ratio is 0.55 to 1.0 with respect to strontium hydroxide added in the neutralization reaction.
　チタン酸ストロンチウム微粒子生成させる反応溶液の反応濃度はチタン化合物換算で０．０５～０．７ｍｏｌ／Ｌが好ましい。０．０５ｍｏｌ／Ｌ未満の場合、収率が低く工業的ではなく、０．７ｍｏｌ／Ｌ以上の場合、反応溶液中の水酸化ストロンチウム量が溶解度を超えるため、Ｓｒ（ＯＨ）２が析出し、均一な液相反応を行うことが困難である。 The reaction concentration of the reaction solution for producing strontium titanate fine particles is preferably 0.05 to 0.7 mol / L in terms of titanium compound. If it is less than 0.05 mol / L, the yield is low and not industrial, and if it is 0.7 mol / L or more, the amount of strontium hydroxide in the reaction solution exceeds the solubility, so Sr (OH) 2 is precipitated, It is difficult to perform a uniform liquid phase reaction.
　反応中は窒素をフローさせて、バリウム化合物と空気中の炭酸ガス等とが反応しないように制御することが好ましい。 It is preferable to control nitrogen gas to flow so that the barium compound does not react with carbon dioxide in the air during the reaction.
　湿式反応の反応温度は６０～２５０℃が好ましい。６０℃未満の場合には、緻密な球状チタン酸ストロンチウム微粒子を得ることが困難となる。２５０℃を超える場合、水熱容器の設計が困難である。好ましくは６５～１９０℃である。なお、水酸化ストロンチウム水溶液を添加するときの温度とその後、反応させる温度とは同じであっても、異なっていても良い。 The reaction temperature of the wet reaction is preferably 60 to 250 ° C. When the temperature is less than 60 ° C., it is difficult to obtain dense spherical strontium titanate fine particles. When it exceeds 250 ° C., it is difficult to design a hydrothermal container. Preferably, it is 65 to 190 ° C. The temperature at which the aqueous strontium hydroxide solution is added and the temperature at which the reaction is performed thereafter may be the same or different.
　湿式反応後の粒子は、常法に従って水洗、乾燥する。水洗することによって、過剰のストロンチウムを洗い流すことができる。また、不純物であるＮａ、Ｋ、及びＣｌなども同時に除去することができる。 The particles after the wet reaction are washed with water and dried according to a conventional method. Excess strontium can be washed away by washing with water. In addition, impurities such as Na, K, and Cl can be removed at the same time.
　また、本発明においては、粉砕・解砕処理を行ってもよい。 Further, in the present invention, pulverization / disintegration treatment may be performed.
　上記の方法によって得られた本発明のチタン酸ストロンチウム微粒子粉末は分散性に優れる。すなわち凝集による二次粒子が少ないため、平均一次粒子径と一次粒子径（Ｄ５０）との差が小さい。以下の式で評価される分散性は、好ましくは５％以下、より好ましくは２％以下である。
｛（一次粒子径（Ｄ５０）－平均一次粒子径）／平均一次粒子径｝×１００（％） The strontium titanate fine particle powder of the present invention obtained by the above method is excellent in dispersibility. That is, since there are few secondary particles by aggregation, the difference of an average primary particle diameter and a primary particle diameter (D50) is small. The dispersibility evaluated by the following formula is preferably 5% or less, more preferably 2% or less.
{(Primary particle diameter (D50) −Average primary particle diameter) / Average primary particle diameter} × 100 (%)
　本発明の代表的な実施の形態は、次の通りである。 A typical embodiment of the present invention is as follows.
　チタン酸ストロンチウム微粒子粉末を走査型電子顕微鏡（（株）日立製作所Ｓ－４３００）によって観察した写真（倍率５万倍）について、約２５０個の粒子から平均一次粒子径及び粒度分布の一次粒子径（Ｄ５０）を計測した。ここで、平均一次粒子径とは各々の粒子に対して写真から求まる面積と同等面積の円の直径を粒子径とし、それを測定全粒子に対して平均した粒子径である。また、Ｄ５０とは測定粒子の個数を１００％とし、粒子径に対する累積割合を求めたときの累積割合が５０％となる粒子径である。また、粒子形状は前記電子顕微鏡写真から判断した。さらに、球形度は、前記電子顕微鏡写真から測定した粒子の（４π×面積）／（２×周囲長）で示した。 About a photograph (magnification of 50,000 times) of the strontium titanate fine particle powder observed with a scanning electron microscope (Hitachi, Ltd. S-4300), an average primary particle size and a primary particle size distribution of about 250 particles ( D50) was measured. Here, the average primary particle diameter is a particle diameter obtained by setting the diameter of a circle having an area equivalent to the area obtained from the photograph for each particle as the particle diameter and averaging the diameter for all the measured particles. D50 is a particle diameter at which the cumulative ratio is 50% when the number of measured particles is 100% and the cumulative ratio with respect to the particle diameter is determined. The particle shape was determined from the electron micrograph. Further, the sphericity was indicated by (4π × area) / (2 × perimeter) of particles measured from the electron micrograph.
　結晶構造は、「Ｘ線回折装置　ＳｍａｒｔＬａｂ」（理学電機工業（株）製）（管球：Ｃｕ）を使用し、２θが１０～９０°の範囲で測定し、ＷＰＰＦ法を用いて格子定数を算出した。結晶子サイズは、Ｈａｌｄｅｒ－Ｗａｇｎｅｒ法を用いて算出した。 The crystal structure was measured using an “X-ray diffractometer SmartLab” (manufactured by Rigaku Denki Kogyo Co., Ltd.) (tube: Cu), and 2θ was measured in the range of 10 to 90 °, and the lattice constant was determined using the WPPF method. Calculated. The crystallite size was calculated using the Halder-Wagner method.
　比表面積値はＢＥＴ法により測定した値で示した。 The specific surface area value is a value measured by the BET method.
　チタン酸ストロンチウム微粒子粉末の分散性の評価は、上記で得られた平均一次粒子径及び粒度分布の一次粒子径（Ｄ５０）より以下の式で判断した。
｛（一次粒子径（Ｄ５０）－平均一次粒子径）／平均一次粒子径｝×１００（％） The dispersibility of the strontium titanate fine particle powder was evaluated by the following formula from the average primary particle size and the primary particle size (D50) of the particle size distribution obtained above.
{(Primary particle diameter (D50) −Average primary particle diameter) / Average primary particle diameter} × 100 (%)
　実施例１：
　Ｔｉのモル濃度が１．３５ｍｏｌ／ｌである四塩化チタン水溶液を調整し、これに２０ｗｔ％の水酸化ストロンチウム水溶液をＳｒ／Ｔｉモル比が１．４５になるように加え水酸化チタンスラリーを得た（中和反応）。そのスラリーを窒素置換した反応容器に投入し攪拌しながら９０℃に加温した後、２０ｗｔ％の水酸化ストロンチウム水溶液をＳｒ／Ｔｉモル比で１．２になるように加えた。なお、湿式反応で添加した水酸化ストロンチウムは、中和反応で用いた水酸化ストロンチウムに対してモル比で０．８３であった。その後９０℃で３時間攪拌を続け反応を終了した。反応後室温まで冷却した後、ヌッチェでろ液の電気伝導度が５００μＳ／ｃｍになるまで水洗し、ろ過、乾燥を行なって立方晶系チタン酸ストロンチウム微粒子の白色粉末を得た。 Example 1:
A titanium tetrachloride aqueous solution having a Ti molar concentration of 1.35 mol / l was prepared, and a 20 wt% strontium hydroxide aqueous solution was added thereto so that the Sr / Ti molar ratio was 1.45 to obtain a titanium hydroxide slurry. (Neutralization reaction). The slurry was put into a reaction vessel purged with nitrogen and heated to 90 ° C. with stirring, and then a 20 wt% strontium hydroxide aqueous solution was added so that the molar ratio of Sr / Ti was 1.2. The strontium hydroxide added by the wet reaction was 0.83 in molar ratio with respect to the strontium hydroxide used in the neutralization reaction. Thereafter, stirring was continued at 90 ° C. for 3 hours to complete the reaction. After the reaction, the reaction mixture was cooled to room temperature, washed with Nutsche until the filtrate had an electric conductivity of 500 μS / cm, filtered and dried to obtain white powder of cubic strontium titanate fine particles.
　得られたチタン酸ストロンチウム微粒子粉末を電子顕微鏡で観察すると、一次平均粒子径が５２．６ｎｍ、球形度０．８６の球状粒子であり、粉末Ｘ線回折測定から結晶子サイズが２４５Åのチタン酸ストロンチウム単相であることが確認できた。 When the obtained strontium titanate fine particle powder is observed with an electron microscope, it is a spherical particle having a primary average particle diameter of 52.6 nm and a sphericity of 0.86, and a crystallite size of 245 mm from a powder X-ray diffraction measurement. It was confirmed to be a single phase.
　実施例２～６及び比較例１：
　反応濃度、中和及び晶析時の水酸化ストロンチウム量、反応温度、時間を変化させた以外は実施例１と同様にしてチタン酸ストロンチウム微粒子粉末を得た。なお、実施例４は水熱容器中で行った。 Examples 2 to 6 and Comparative Example 1:
Strontium titanate fine particle powder was obtained in the same manner as in Example 1 except that the reaction concentration, the amount of strontium hydroxide during neutralization and crystallization, the reaction temperature, and the time were changed. In addition, Example 4 was performed in the hydrothermal container.
　このときの製造条件を表１に、得られたチタン酸ストロンチウムの粉体特性を表２に示す。 The production conditions at this time are shown in Table 1, and the powder characteristics of the obtained strontium titanate are shown in Table 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２から明らかなように、実施例１～６で得られたチタン酸ストロンチウムは分散性に優れる。一方、中和反応を行わず１段階でチタン酸ストロンチウムを得た比較例１では、平均一次粒子径と一次粒子径（Ｄ５０）との差が大きく、凝集粒子の影響が認められ、分散性に優れるとはいえない。 As is clear from Table 2, the strontium titanates obtained in Examples 1 to 6 are excellent in dispersibility. On the other hand, in Comparative Example 1 in which strontium titanate was obtained in one step without performing the neutralization reaction, the difference between the average primary particle size and the primary particle size (D50) was large, and the influence of the aggregated particles was recognized, and the dispersibility was improved. Not good.
　本発明に係るチタン酸ストロンチウム微粒子粉末は、目的に応じて平均粒子径をコントロールすることができ、かつ結晶性が高く球状であるため充填密度を上げやすいという特徴がある。したがって、本発明のチタン酸ストロンチウム微粒子粉末はセラミックコンデンサを始めとした電子部品用途、反射材や集光材等の光学用途、触媒や熱電材に最適である。 The strontium titanate fine particle powder according to the present invention is characterized in that the average particle diameter can be controlled according to the purpose, and the packing density is easily increased because it is highly crystalline and spherical. Therefore, the strontium titanate fine particle powder of the present invention is most suitable for use in electronic parts such as ceramic capacitors, optical use such as a reflecting material and a light collecting material, a catalyst and a thermoelectric material.

Claims (3)

  1. 　立方晶系チタン酸ストロンチウムであって、一次粒子の平均一次粒子径が５０～１５０ｎｍであって球形度が０．８以上であることを特徴とするチタン酸ストロンチウム微粒子粉末。 A strontium titanate fine particle powder, which is cubic strontium titanate, having an average primary particle diameter of primary particles of 50 to 150 nm and a sphericity of 0.8 or more.
  2. 　請求項１記載のチタン酸ストロンチウム微粒子粉末であって、結晶子サイズが２００Å以上であるチタン酸ストロンチウム微粒子粉末。 The strontium titanate fine particle powder according to claim 1, wherein the strontium titanate fine particle powder has a crystallite size of 200 mm or more.
  3. 　四塩化チタン水溶液を水酸化ストロンチウム水溶液で中和することで得た含水水酸化チタンスラリーを加熱した後、水酸化ストロンチウム水溶液を添加し６０～２００℃の温度範囲で湿式反応させることを特徴とする請求項１又は２に記載のチタン酸ストロンチウム微粒子粉末の製造方法。　 A water-containing titanium hydroxide slurry obtained by neutralizing an aqueous solution of titanium tetrachloride with an aqueous solution of strontium hydroxide is heated, and then an aqueous solution of strontium hydroxide is added to perform a wet reaction in a temperature range of 60 to 200 ° C. The manufacturing method of the strontium titanate fine particle powder of Claim 1 or 2. *
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JP7336010B2 (en) 2018-03-01 2023-08-30 チタン工業株式会社 Method for producing strontium titanate
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CN105502480A (en) * 2015-10-16 2016-04-20 浙江大学 Hydrangea-like strontium titanate nano powder preparation method
JP2018020919A (en) * 2016-08-02 2018-02-08 チタン工業株式会社 Strontium titanate-based fine particle for toner and manufacturing method therefor
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US10488776B2 (en) * 2017-07-28 2019-11-26 Fuji Xerox Co., Ltd. Electrostatic charge image developing toner, electrostatic charge image developer, and toner cartridge
JP7131926B2 (en) 2018-03-01 2022-09-06 チタン工業株式会社 Strontium titanate powder, method for producing the same, and external additive for electrophotographic toner
JP2019151507A (en) * 2018-03-01 2019-09-12 チタン工業株式会社 Strontium titanate powder, production method thereof and external additive for electric photograph toner
JP7336010B2 (en) 2018-03-01 2023-08-30 チタン工業株式会社 Method for producing strontium titanate
JP7003765B2 (en) 2018-03-20 2022-01-21 富士フイルムビジネスイノベーション株式会社 Static charge image developer, process cartridge, image forming apparatus, and image forming method
JP2019164292A (en) * 2018-03-20 2019-09-26 富士ゼロックス株式会社 Electrostatic charge image developer, process cartridge, image formation device, and image formation method
WO2023008395A1 (en) 2021-07-30 2023-02-02 戸田工業株式会社 Strontium titanate fine-particle powder and method for producing same, dispersion, and resin composition
JP7343074B1 (en) 2021-10-15 2023-09-12 戸田工業株式会社 Strontium titanate fine particle powder and dispersion, resin composition
CN115417446A (en) * 2022-08-17 2022-12-02 浙江大学 Preparation method of strontium titanate micro-nano structure flower ball and product thereof
CN115417446B (en) * 2022-08-17 2023-10-20 浙江大学 Preparation method of strontium titanate micro-nano structured flower ball and product thereof

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