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Z27,720 (ZZZZ Patent Application Publication Nov US 20070253145A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0253145 A1 Kurozumi et al. (43) Pub. Date: Nov. 1, 2007 (54) BARIUM CALCIUM TITANATE, (30) Foreign Application Priority Data PRODUCTION PROCESS THEREOF AND CAPACTOR Aug. 27, 2004 (JP)...................................... 2004-248205 (75) Inventors: Tadatoshi Kurozumi, Funabashi-shi Publication Classification (JP); Akihiko Shirakawa, Chiba-shi (JP) (51) Int. Cl. COIG 23/00 (2006.01) Correspondence Address: C04B 35/468 (2006.01) SUGHRUE MION, PLLC HOIG 4/12 (2006.01) 2100 PENNSYLVANIAAVENUE, N.W. SUTE 800 (52) U.S. Cl. ....................... 361/321.4; 423/598: 501/137 WASHINGTON, DC 20037 (US) (73) Assignee: SHOWDA DENKO K.K., TOKYO (JP) (57) ABSTRACT (21) Appl. No.: 11/660,606 A barium calcium titanate of the present invention has a (22) PCT Filed: Aug. 26, 2005 remarkable effect that a fine barium calcium titanate powder PCT No.: PCT/JP05/16055 having excellent dispersibility, reduced impurities and high (86) crystallinity and being solid-dissolved at an arbitrary ratio, S 371(c)(1), and a production process thereof are provided. (2), (4) Date: Feb. 20, 2007 The barium calcium titanate represented by the composi Related U.S. Application Data tional formula: (Ba-Cax). TiO, (wherein 0<x<0.2 and 0.98s Ys 1.02), which contains 3 mol % or less (including (60) Provisional application No. 60/606,888, filed on Sep. 0 mol%) of an orthorhombic perovskite compound and in 3, 2004. which the specific surface area D is from 1 to 100 m/g. Y/////2 (1/ N SNS W NNN WWN N NN WN NN-P-P-O-PI-RO N WNN NNN W Z27,720 (ZZZZ Patent Application Publication Nov. 1, 2007 Sheet 1 of 13 US 2007/02531.45 A1 FIG. 1 $2 WN,N1 SNNNW N, ////// (//////SS Patent Application Publication Nov. 1, 2007 Sheet 2 of 13 US 2007/02531.45 A1 FIG 2 Patent Application Publication Nov. 1, 2007 Sheet 3 of 13 US 2007/02531.45 A1 £º£)IH 0009 0007 000€ INTENSTY (COUNT) Patent Application Publication Nov. 1, 2007 Sheet 4 of 13 US 2007/02531.45 A1 FIG. 4 Patent Application Publication Nov. 1, 2007 Sheet 5 of 13 US 2007/02531.45 A1 FIG. 5 s 100nm Patent Application Publication Nov. 1, 2007 Sheet 6 of 13 US 2007/02531.45 A1 9°{DIH '07000°OZ'09000000 000G 000?7 000€ 000Z 000|| INTENSTY (COUNT) Patent Application Publication Nov. 1, 2007 Sheet 7 of 13 US 2007/02531.45 A1 FIG. 7 3. Patent Application Publication Nov. 1, 2007 Sheet 8 of 13 US 2007/02531.45 A1 Patent Application Publication Nov. 1, 2007 Sheet 9 of 13 US 2007/02531.45 A1 FIG. Patent Application Publication Nov. 1, 2007 Sheet 10 of 13 US 2007/02531.45 A1 ()I"OIH 0009 0007 0009 000Z 000|| INTENSTY (COUNT) Patent Application Publication Nov. 1, 2007 Sheet 11 of 13 US 2007/02531.45 A1 O Cd o c co vue vm C es gd s O a1 O (dCd O) m N co O Cd c r C C O O OOO OO sO S es: s INTENSITY (COUNT) Patent Application Publication Nov. 1, 2007 Sheet 12 of 13 US 2007/02531.45 A1 ZI"OIH 000G 0007 0008 INTENSTY (COUNT) Patent Application Publication Nov. 1, 2007 Sheet 13 of 13 US 2007/02531.45 A1 Co cd C c co van & an c na Ct 3 CNOD m Cd Kd Co cs re d O d cs cN INTENSTY (COUNT) US 2007/02531.45 A1 Nov. 1, 2007 BARIUM CALCIUM TITANATE, PRODUCTION 0008 For example, in order to obtain a downsized, PROCESS THEREOF AND CAPACTOR lightweight and high-capacitance multilayer ceramic capaci tor, the particle diameter of the barium calcium titanate must TECHNICAL FIELD be made Small, thereby decreasing the distance between layers stacked and increasing the number of layers Stacked. 0001. The present invention relates to a particulate In general, when the particle diameter of the barium calcium barium calcium titanate used for electronic materials such as titanate becomes Small, the c?a ratio decreases and the dielectric material, piezoelectric material, pyroelectric mate crystal comes close to a cubic crystal, but if the c?a ratio rial, multilayer ceramic capacitor and thin-film material, and decreases, this leads to decrease in the ferroelectricity and on a production process thereof. use as a dielectric material, decrease in the electrostatic 0002 More specifically, the present invention relates to a capacitance. To solve this problem, a barium calcium titan particulate barium calcium titanate represented by the for ate exhibiting a high cfa ratio despite a small particle is mula: (Baix,Ca). TiO, (0<x<0.2,0.98s Ys 1.02), which demanded. In order to exhibit a high c/a ratio, the barium contains 3 mol % or less of an orthorhombic perovskite calcium titanate must be highly crystalline. compound and in which assuming that the specific Surface 0009. Also, if the barium calcium titanate powder under area D is from 1 to 100 m/g and the ratio of the c-axis length goes aggregation at the time of mixing the powder with a to the a-axis length determined from the a-axis length (unit: Solvent to form a slurry or a paste, the sintering density nm) and the c-axis length (unit: nm) of a crystal lattice as decreases and in turn the electric properties such as break calculated by the Rietveld method is y, D and y satisfy a down voltage and migration deteriorate. Furthermore, impu specific relationship. rities contained in the barium calcium titanate have adverse 0003 Priority is claimed on Japanese Patent Application effect on the electric properties. No. 2004-248205, filed Aug. 27, 2004, the content of which 0010. Accordingly, in order to cope with downsized, is incorporated herein by reference. This application is an lightweight and high-performance electronic parts, develop application filed under 35 U.S.C. 111(a) claiming pursuant ment of a barium calcium titanate having a small particle to 35 U.S.C. 119(e) of the filing date of Provisional Appli diameter, a narrow particle size distribution, excellent dis cation 60/606,888 on Sep. 3, 2004, pursuant to 35 U.S.C. persibility and high purity is necessary. 111(b). 0011 Conventionally, the barium titanate has been pro duced by the following process. BACKGROUND ART 0012. As for the production process of a high-purity 0004 The barium titanate takes a perovskite-type struc high-crystalline particulate barium titanate, a flux process is ture where barium and Ti occupy the A site and the B site, known. However, in this process, not only the production respectively, and titanium is slightly deviated from the cost is very high but also the particle formation can be center. By virtue of this structure, the barium titanate effected only by grinding and therefore, the particles have a expresses ferroelectricity and in turn excellent electric prop broad particle size distribution and poor dispersibility. erties such as dielectricity, piezoelectiricity and pyroelec Accordingly, this process is unsuitable for the electronic tricity and therefore, is being widely used as various elec materials using a particle material. tronic materials. 0013 As for the process of producing a barium titanate 0005 Also, the barium calcium titanate is widely used as for electronic materials, there is generally known, for a barium titanate-based electronic material resulting from example, a Solid-phase process of mixing powders of an replacing a part of barium by calcium and in particular, the oxide and a carbonate used as raw materials in a ball mill or barium calcium titanate is attracting attention as a ceramic the like and reacting the mixture at a high temperature of capacitor material in which the temperature dependency and about 800° C. or more to produce a barium titanate; an reliability of dielectric property of the barium titanate are oxalate process of preparing an oxalic acid composite salt improved. and thermally decomposing the composite salt to obtain a 0006 Examples of the usage thereof include, by making titanium-containing composite oxide particle; a hydrother use of high dielectricity of this material, various capacitor mal synthesis process of reacting raw materials in an aque materials (including multilayer ceramic capacitor), dielec ous solvent at high temperature and high pressure to obtain tric filter, dielectric antenna, dielectric resonator, dielectric a precursor, and an alkoxide process of using a metal duplexer, capacitor and phase shifter, and also include alkoxide as a raw material and hydrolyzing it to obtain a stacked piezoelectric actuator utilizing piezoelectricity. As precursor. for the method of using the barium titanate in an electronic 0014. Also, with respect to the production process of a material, there is a method of mixing a barium titanate barium titanate, for example, a process of reacting a powder with a solvent to form a slurry or a paste, and hydrolysate of a titanium compound with a water-soluble shaping it into a thin film or a porcelain by molding, barium salt in a strong alkali (Patent Document 1), and a sintering, sheeting or the like. process of reacting a titanium oxide Sol with a barium 0007. In recent years, it is demanded to develop a barium compound in a strong alkali aqueous solution (Patent Docu calcium titanate having a small particle diameter, a narrow ment 2) are generally known, and studies are being aggres particle size distribution, excellent dispersibility, high crys sively made to improve these synthesis methods. tallinity and high purity and being capable of coping with 0015 The solid-phase process has a problem that despite down-sized, lightweight and high-performance electronic low production cost, the produced particulate barium titan parts.
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