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 , (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

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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

particle diameter may be decreased but the particle size a barium calcium titanate capable of coping with down distribution is broadened and the shaping density may not be sized, lightweight and high-performance electronic parts. enhanced. Furthermore, distortion may be generated in the Furthermore, in order to uniformly solid-dissolve barium crystal structure due to the effect of grinding and a barium and calcium, a heat treatment at a high temperature is titanate powder Suitable for down-sized high-performance necessary but this allows the particle to readily grow and electronic parts may not be obtained. disadvantageously makes it difficult to produce a fine par 0016. In the oxalate process, a smaller particle than that ticulate barium calcium titanate. produced by the Solid-phase process is obtained, but a 0026 Patent Documents 3, 4 and 5 each discloses a carbonate group derived from the oxalic acid remains as an production process of a barium calcium titanate. impurity. Furthermore, a large amount of a hydroxyl group 0027. In the processes described in Patent Documents 3 attributable to water taken into the inside remains and this and 4, a fine barium calcium titanate can be obtained, but deteriorates the electric properties. In this way, the oxalate since a barium compound and a calcium compound are process is disadvantageous in that a barium titanate powder simultaneously charged, an orthorhombic perovskite com with excellent electric properties cannot be obtained. pound is mingled as a by-product of a competitive reaction. 0017. The hydrothermal synthesis process has a problem that although a fine particulate barium titanate is obtained, a 0028. Furthermore, the process described in Patent Docu hydroxyl group attributable to water taken into the inside ment 4 uses a very complicated step and requires an expen remains to cause many defects and a particulate barium sive titanium alkoxide. titanate with excellent electric properties can be hardly 0029. In the process described in Patent Document 5, obtained. Also, this process is performed under high-tem calcium carbonate, titanium oxide and barium titanate are perature high-pressure conditions and therefore, exclusive heat-treated at 1,000° C. or more and therefore, a fine barium equipment is necessary and the cost rises. calcium titanate of 0.2 um or less cannot be obtained. 0018. In the alkoxide process, a barium titanate finer than 0030. An object of the present invention is to provide a that produced by the hydrothermal synthesis process is barium calcium titanate having a small particle diameter, a obtained, but a hydroxyl group attributable to water taken narrow particle size distribution, excellent dispersibility, into the inside remains to cause many defects and a titanium high crystallinity and excellent electric properties; and a containing composite oxide with excellent electric proper production process thereof. ties can be hardly obtained. 0031. In order to attain this object, the present invention 0019 Patent Document 1: JP-B-3-39014 (the term “JP provides the following means. B” as used herein means an “examined Japanese patent publication') 0032 1. A barium calcium titanate represented by the compositional formula: (Baix Cax). TiO, (wherein 0020 Patent Document 2: International Patent Publica 0

diameter on the Volume basis as determined by the image 0048 17. The process for producing a barium calcium analysis method is D1, the particle diameter when the titanate as claimed in any one of 9 to 16), wherein the volume accumulated from the smaller particle diameter side basic compound is an organic base compound. reaches 95% is D3 and the maximum particle diameter is 0049. 18. The process for producing a barium calcium D4, D3/D1 is from 1 to 1.8 and D4/D1 is from 1 to 2. titanate as claimed in any one of 9 to 17), wherein the 0038 7. The barium calcium titanate as claimed in any basic compound is tetramethylammonium hydroxide. one of 1 to 6), which is a powder having a specific surface 0050 19 A dielectric material comprising the barium area D of 5 to 100 m/g. calcium titanate claimed in any one of 1 to 8. 0039) 8 The barium calcium titanate as claimed in any one of 1 to 7), wherein X in the compositional formula is 0051 20 A paste comprising the barium calcium titan 0.05sX&O.2. ate claimed in any one of 1 to 8). 0052 (21 A slurry comprising the barium calcium titan 004.0 9. A process for producing a barium calcium ate claimed in any one of 1 to 8). titanate, comprising a step of synthesizing a barium titanate by charging a barium hydroxide and a titanium oxide into a 0053 22 A thin-film shaped product comprising the basic compound-containing basic Solution at a pH of 10 or barium calcium titanate claimed in any one of 1 to 8. more and allowing the reaction to proceed, a step of syn 0054) 23A dielectric porcelain produced by using the thesizing a barium calcium titanate by charging a calcium barium calcium titanate claimed in any one of 1 to 8. hydroxide and allowing the reaction to proceed, and a step of vaporizing and removing the basic compound. 0055 24 Apyroelectric porcelain produced by using the barium calcium titanate claimed in any one of 1 to 8. 0041) 10 The process for producing a barium calcium titanate as claimed in 9), wherein the molar ratio of the 0056 25 A piezoelectric porcelain produced by using barium hydroxide and the calcium hydroxide is set to from the barium calcium titanate claimed in any one of 1 to 8. 1:0 to 0.8:0.2, the amount of the titanium oxide is set to from 0057 26A capacitor comprising the dielectric porcelain 0.98 to 1.02 times the total molar amount of the barium claimed in 23). hydroxide and the calcium hydroxide, and these barium 0058. 27. An electronic device comprising at least one hydroxide, calcium hydroxide and titanium oxide are member selected from the group consisting of the thin-film reacted in a basic solution to produce a barium calcium shaped product, the porcelain and the capacitor claimed in titanate. any one of 22 to 26). 0.042 11 The process for producing a barium calcium 0059 28 A sensor comprising one species or two or titanate as claimed in 9 or 10, wherein the reaction in the more species of the thin-film shaped product or porcelain step of synthesizing a barium titanate is continued until the claimed in any one of 22 to 25). amount of barium ion remaining in the basic Solution becomes 1/100 or less of the amount charged, and the 0060 29 A dielectric film comprising the barium cal reaction in the step of synthesizing a barium calcium titanate cium titanate claimed in any one of 1 to 8. is continued until the residual amount of calcium ion 0061 30 A capacitor produced by using the dielectric becomes 1/100 or less of the amount charged. film claimed in 29). 0.043 12 The process for producing a barium calcium 0062) The barium calcium titanate as a preferred embodi titanate as claimed in any one of 9 to 11), wherein after the ment of the present invention has a remarkable effect that a step of removing the basic compound, the barium calcium fine barium calcium titanate powder having excellent dis titanate is heat-treated at 350 to 1200° C. persibility, reduced impurities and high crystallinity and 0044 13. The process for producing a barium calcium being Solid-dissolved at an arbitrary ratio, and a production titanate as claimed in any one of 9 to 1.2), wherein in the process thereof are provided. process from the synthesis of a barium titanate to the 0063. This barium calcium titanate powder and a slurry synthesis of a barium calcium titanate, the concentration of or paste containing the powder can exert excellent electric a carbonate group in the reaction Solution is controlled to be properties, and a dielectric material, a piezoelectric material, from 0 to 500 ppm in terms of CO. a pyroelectric material or the like having excellent perfor mance, such as porcelain, thin film and dielectric film, can 0045 14. The process for producing a barium calcium be obtained therefore. Furthermore, by using such a material titanate as claimed in any one of 9 to 13), wherein the for an electronic device, a down-sized lightweight electronic titanium oxide contains a crystal. device can be realized. The dielectric film has excellent 0046) 15 The process for producing a barium calcium electric property and therefore, even when formed into a thin titanate as claimed in any one of 9 to 14), wherein the film, the dielectric film can exert excellent properties and titanium oxide is a titanium oxide sol obtained by hydro can be applied to an in-substrate capacitor or the like. Use lyzing a titanium compound in an acidic solution. of this capacitor in electronic devices such as cellular phone or digital camera is very effective for the realization of a 0047. 16. The process for producing a barium calcium down-sized, lightweight and high-performance device. titanate as claimed in any one of 9 to 15), wherein the basic compound is a Substance which undergoes vaporiza BRIEF DESCRIPTION OF THE DRAWINGS tion by any one or more means of evaporation, Sublimation 0064 FIG. 1 is one example of a cross-sectional sche and thermal decomposition under atmospheric pressure or matic view of a multilayer ceramic capacitor as a preferred reduced pressure. embodiment of the present invention. US 2007/02531.45 A1 Nov. 1, 2007

0065 FIG. 2 is one example of an exploded view show erties can be attained. For example, the dielectric constant at ing one example of the internal structure of a cellular phone room temperature is about 1,600 in the case of barium equipped with the multilayer ceramic capacitor of FIG. 1. titanate (X=0), and about 900 in the case of calcium barium 0.066 FIG. 3 is one example of an X-ray diffraction titanate (X=0.15). In the barium calcium titanate of the spectrum diagram of the BaolosoCaoosoTiOs powder of present invention, X and Y values can be controlled with Example 1. precision of 1/100 or less, preferably 1/1,000. By adjusting the Solid-solution ratio of barium and calcium in this way, a 0067 FIG. 4 is one example of a scanning electron barium calcium titanate of which dielectric constant at room microphotograph of the BaolosoCaooseTiO powder of temperature is adjusted to a desired value can be obtained. Example 1. 0081. The ratio (Y) of the total molar number of barium 0068 FIG. 5 is one example of a transmission electron and calcium to the molar number of titanium is preferably microphotograph of the BaolosoCaoosoTiOs powder of from 0.98 to 1.02, more preferably from 0.99 to 1.01, still Example 1 and an elementary analysis diagram by EDX. more preferably from 0.995 to 1.005, and this ratio is 0069 FIG. 6 is one example of an X-ray diffraction adjusted so that desired electric properties can be attained. spectrum diagram of the Bacoso Cao osoTiO powder of The ratio Y is preferably closer to 1, because the defects are Example 2. less generated and the crystallinity becomes higher. 0082 In order to improve the electric properties of the 0070 FIG. 7 is one example of a scanning electron barium calcium titanate in a preferred embodiment of the microphotograph of the BaolosoCaoosoTiOs powder of present invention, another compound may be added and Example 2. used and this causes no trouble. 0071 FIG. 8 is one example of a transmission electron 0083. In general, for the purpose of downsizing of an microphotograph of the BaolosoCaooseTiO powder of electronic device, if a specific surface area is less than 1 m/g Example 2 and an elementary analysis diagram by EDX. the powder is not effective, because the particle diameter is 0072 FIG. 9 is one example of a transmission electron excessively large, whereas if the specific Surface area microphotograph when the BaolosoCaoosoTiOs powder of exceeds 100 m/g, the powder readily undergoes aggrega Example 2 was observed at a magnification of 250,000. tion and its handling becomes difficult. The barium calcium 0073 FIG. 10 is one example of an X-ray diffraction titanate in a preferred embodiment of the present invention spectrum diagram of the Bacoso Cao osoTiO powder of has a specific surface area of 1 to 100 m/g, preferably from Comparative Example 1. 5 to 70 m/g, more preferably from 5 to 50 m/g. Inciden tally, a specific surface area determined by the BET method 0074 FIG. 11 is one example of an X-ray diffraction is preferably employed in the present invention. spectrum diagram obtained by enlarging FIG. 10. 0084. The relationship between the length of c-axis 0075 FIG. 12 is one example of an X-ray diffraction length and a-axis length to (for) the Ca-replacing amount is spectrum diagram of the BaolosoCaoosoTiOs powder of described, for example, in J. Amer: Ceram. Soc., 38, 142 Comparative Example 2. (1955). As the Ca-replacing amount is larger, the c-axis length and a-axis length are Smaller. Assuming that the 0076 FIG. 13 is one example of an X-ray diffraction specific surface area as determined by the BET method is D spectrum diagram obtained by enlarging FIG. 12. (unit m/g) and the ratio (c/a) of the c-axis length to the 0077. The reference numerals shown in Fig.s are defined a-axis length as determined by the Rietveld method is y, the as follows: 1. Multilayer ceramic capacitor (capacitor); 2. barium calcium titanate in a preferred embodiment of the Dielectric layer. present invention satisfies the following formula (1) or (2) and is characterized in that the particle is a fine particle and BEST MODE FOR CARRYING OUT THE has a high cfa ratio. INVENTION y21.0095-8.8x10'x D (provided that when 0078. The present invention is described in detail below. 1sDs9.7) (1) y21.003 (provided that when 9.7&Ds 100) (2) 0079 The barium calcium titanate in a preferred embodi 0085. In the barium calcium titanate in a preferred ment of the present invention is a solid-solution perovskite embodiment of the present invention, an orthorhombic per type compound represented by the formula (BayCax)y- ovskite compound as a by-product may be contained in a TiO, (0

0101 More preferably, a BaocooCacooTiOooo powder when mechanical stirring is applied, the raw materials are can be produced by charging barium hydroxide:calcium intermingled with each other and this is preferred. The hydroxide:titanium oxide=99.0 mol: 1.0 mol: 100.0 mol, and reaction Solution is basic and readily absorbs CO in air and a BacoocCaolo TiOooo powder can be produced by charg therefore, the reaction is preferably performed in a closed ing barium hydroxide:calcium hydroxide: titanium oxide= state or while blowing an inert gas so that the reaction 90.0 mol:10.0 mol:100.0 mol. solution can be prevented from contacting with air. If CO, is absorbed into the reaction solution, this is contained as a 0102) In the process for producing a barium calcium carbonate group in the reaction solution. This carbonate titanate according to a preferred embodiment of the present group (the carbonate species including CO, HCO, HCO invention, a basic Solution in which a basic compound is and CO) reacts with a barium hydroxide or a calcium present is preferably used. The reason therefor is not clearly hydroxide to produce a stable barium carbonate or calcium known but it is presumed that as the alkalinity is higher, the carbonate. The barium carbonate or calcium carbonate does barium ion and calcium ion are more readily reacted with not react with a titanium oxide and tends to remain as an titanium oxide. The pH of the solution is 10 or more, impurity in the barium calcium titanate. Accordingly, the preferably 13 or more, more preferably 14 or more. The concentration of the carbonate group (in terms of CO: upper limit of the amount charged of a basic compound is a unless otherwise indicated, hereinafter the same) in the saturated solubility of the basic compound in water. reaction solution is preferably controlled. By controlling the 0103) In a preferred embodiment of the present invention, carbonate group concentration, a high-purity barium cal the reaction with titanium oxide in a basic solution at a pH cium titanate can be stably produced. of 10 or more in which a basic compound is present is continued until the residual amount of barium becomes 0111 The concentration in terms of CO in the reaction 1/100 or less, preferably 1/1,000 or less, of the amount solution is preferably from 0 to 500 ppm by mass, more charged, whereby a barium titanate is synthesized. Also, preferably from 0 to 200 ppm by mass, still more preferably after charging a calcium hydroxide, the reaction is continued from 0 to 100 ppm by mass. In order to decrease the until the residual amount of calcium ion becomes 1/100 or concentration of the carbonate group in the reaction solu less, preferably 1/1,000 or less, of the amount charged, tion, the water before dissolving a basic compound therein whereby a barium calcium titanate is produced. By control is preferably decarboxylated by a heat treatment immedi ling the reaction in this way, a barium calcium titanate where ately before the production. the content of calcium hydroxide, barium hydroxide and 0.112. In order to elevate the crystallinity of the barium titanium oxide as raw materials is less than 1/100 mol, calcium titanate, the reaction temperature is preferably as preferably less than 1/1,000, can be produced. In other high as possible. The reaction temperature can be elevated words, a barium calcium titanate in which the X and Y by a hydrothermal reaction from 100° C. to the critical values are controlled to a 1/100 order, preferably a 1/1,000 temperature of the Solution but for performing this reaction, order, can be produced. equipment taking care of safety, such as autoclave, is nec 0104. The amounts of barium ion and calcium after the essary. Therefore, it is preferred that the temperature is reaction can be determined by removing the solid content elevated by boiling to 95° C. or more and the reaction is from the reaction Solution and quantitating the amount of performed while keeping this temperature. each ion in the reaction solution according to an ICP 0113. The reaction time of a barium hydroxide with a spectrometry, an atomic absorption method or the like. titanium oxide is usually 2 hours or more, preferably 3 hours 0105. In the present invention, as described above, the or more, more preferably 4 hours or more. Also, the reaction reaction is continued until the total concentration of ions in time after charging a calcium hydroxide is usually 2 hours the solution after reaction becomes 1/100 or less, preferably or more, preferably 4 hours or more, more preferably 6 hours 1/1,000 or less, more preferably 1/2,000 or less, still more O. O. preferably 1/5,000 or less, yet still more preferably 1/10,000 0114 Examples of the impurity adversely affecting the or less, of the amount charged. By Such a reaction, the electric properties of the barium calcium titanate include reaction conversion to a barium calcium titanate is elevated, trace components such as metal ion and anion. These unreacted raw materials such as hydroxide and titanium impurities may be removed by various methods, for oxide are decreased to give a higher purity, and the crystal example, a method of treating the slurry after the completion linity is enhanced. The decrement of the total concentration of reaction by electrodialysis, ion exchange, water washing, after reaction can be determined by the following formula acid cleaning or permeable membrane. However, in these (3): methods, it must be noted that barium and the like contained in the barium calcium titanate are sometimes ionized simul 0106 Chem. 1 taneously with impurity ion and partially dissolved in the (A1-A2)xL2. (A1+A2) (3) slurry, as a result, not only barium and calcium can be hardly 0107 A1, A2: each is a molar concentration (mol/ml) solid-dissolved at a desired ratio but also defects may be determined by reducing Al ion weight concentration or A2 generated in the crystal to lower the crystallinity. Further ion weight concentration in solution after reaction, more, since the reaction solution is basic, carbon dioxide in air is readily intermixed during the treatment and the car 0108 A1, A2: each is a molar number (mol) of bonate content in the barium calcium titanate sometimes hydroxide charged into reaction, and increases. 0109 L2): an amount (ml) of reaction solution. 0.115. From these reasons, it is preferred to select raw 0110. The above-described synthesis reaction is most materials reduced in impurities and at the same time, prevent industrially performed by stirring under heat. In particular, mixing of impurities during the synthesis reaction and firing. US 2007/02531.45 A1 Nov. 1, 2007

In addition, after the completion of synthesis reaction, 100 mass %, preferably from 10 to 100 mass %, more impurities are preferably removed in the form of a gas preferably from 50 to 100 mass %. In order to obtain a through evaporation, Sublimation and/or thermal decompo titanium oxide powder having excellent dispersibility in a sition at a temperature from room temperature to firing Solvent, crystalline structure is more preferred than amor possible temperature under atmospheric pressure or reduced phous structure, because simple particles is readily formed. pressure. At this time, the basic compound contained in the Particularly, the brookite titanium oxide exhibits excellent alkali solution is preferably decomposed at the same time dispersibility. The reason therefor is not clearly known but and removed in the form of a gas. this is considered to have relationship with the fact the Zeta potential of brookite crystal at a pH of 2 is higher than that 0116. The firing is generally performed for enhancing the of -type or -type crystal. crystallinity of titanium-containing composite but on the other hand, impurities can be evaporated, Sublimated 0.122 Examples of the process for producing a titanium and/or thermally decomposed by firing and removed in the oxide powder containing a brookite crystal include a pro form of a gas. Examples of the impurity removable by this duction process in which an anatase-type titanium oxide method include organic amines having a small carbon num powder is heat-treated to obtain a titanium oxide powder ber, organic bases Such as hydroxide of ammonia salt, and containing a brookite crystal; and a liquid-phase production trace organic materials and carbonates contained as impu process in which a solution of a titanium compound Such as rities in raw materials. The firing is usually performed at a titanium tetrachloride, titanium trichloride, titanium alkox firing possible temperature in the range from 350 to 1,200 ide or titanium sulfate is neutralized or hydrolyzed to obtain C. The firing atmosphere is not particularly limited and the a titanium oxide Sol having dispersed therein titanium oxide firing is usually performed in air or under reduced pressure. powder. 0117 Incidentally, after the completion of synthesis reac 0123. In the case of using a brookite crystal-containing tion, the slurry is preferably subjected to Solid-liquid sepa titanium oxide powder as the production raw material, a ration and then fired, because the heat energy necessary for titanium oxide Sol obtained by hydrolyzing a titanium salt in the firing is decreased or the crystallinity is elevated. The an acidic solution is preferably used as the titanium oxide Solid-liquid separation contains the steps of precipitation, powder. The powder of this titanium oxide sol has a small concentration, filtration, and/or drying, and grinding of the particle diameter and excellent dispersibility. The process powder. By the precipitation, concentration and filtration, for producing the titanium oxide sol is preferably, for impurities dissolved in the solution can be removed. A example, a process in which titanium tetrachloride is added coagulant or dispersant may be used so as to change the to hot water at 75 to 100° C., and the titanium tetrachloride precipitation rate or filtration rate. The coagulant or dispers is hydrolyzed while controlling the chloride ion concentra ant is preferably removable as a gas through evaporation, tion at a temperature from 75° C. to the boiling point of the Sublimation and/or thermal decomposition. Solution, thereby obtaining a brookite crystal-containing titanium oxide powder in the form of a sol (see, JP-A-11 0118. The drying step is a step of evaporating the water 43327), or a process where titanium tetrachloride is added to content, but depending on the kind of the basic compound or hot water at 75 to 100° C., and the titanium tetrachloride is impurity, a part or the entire amount of impurities can be hydrolyzed in the existence of one party or both parties of removed through evaporation, Sublimation and/or thermal nitrate ion and phosphate ion, while controlling the total decomposition. For the drying, a method such as drying concentration of chloride ion, nitrate ion and phosphate ion under reduced pressure, hot-air drying or freeze-drying is at a temperature from 75° C. to the boiling point of the used. The drying is usually performed at room temperature Solution, thereby obtaining a brookite crystal-containing to 350° C. for 1 to 24 hours. The drying atmosphere is not titanium oxide powder in the form of a Sol (see, International particularly limited, but the drying is usually performed in Patent Publication WO99/58451, pamphlet). air or inert gas or under reduced pressure. Thereafter, the powder may be ground by an appropriate method. 0.124. As for the size of the thus-obtained brookite crys tal-containing titanium oxide powder, the primary powder 0119) A hydroxide such as the barium hydroxide or diameter is usually from 1 to 100 nm, preferably from 3 to calcium hydroxide for use in the present invention is not 50 um, more preferably from 5 to 20 nm. If the primary particularly limited and may be an anhydrous salt or a powder diameter exceeds 100 nm, the titanium-containing hydrate as long as it is a hydroxide. The barium calcium composite oxide produced by using this powder as the raw titanate of the present invention can also be produced even material comes to have a large particle diameter and is by using a salt of barium and a salt of calcium. Sometimes unsuited for functional materials such as dielec 0120) Furthermore, the titanium oxide sol for use in the tric material and piezoelectric material, whereas if the pri present invention is not particularly limited but is preferably mary powder diameter is less than 1 nm, the handling in the a titanium oxide Sol containing a brookite crystal, or a process of producing the titanium oxide powder may be titanium oxide Sol obtained by hydrolyzing a titanium salt in difficult. an acidic Solution. 0.125. In the case of using a titanium oxide sol obtained 0121. As long as a brookite crystal is contained, the by hydrolyzing a titanium salt in an acidic solution, the titanium oxide Sol may contain a brookite titanium oxide titanium oxide is not limited in its crystal form and not alone or may contain a rutile-type titanium oxide and an limited to a brookite crystal phase. anatase-type titanium oxide. In the case of containing a 0.126 When a titanium salt such as titanium tetrachloride rutile-type titanium oxide and an anatase-type titanium or titanium sulfate is hydrolyzed in an acidic solution, the oxide, the ratio of the brookite titanium oxide in the titanium reaction rate is reduced as compared with the case of oxide is not particularly limited but is generally from 1 to performing the hydrolysis in a neutral or basic Solution and US 2007/02531.45 A1 Nov. 1, 2007

therefore, a titanium oxide sol with simple particle diameter having a small carbon number are weak as a base and and excellent dispersibility is obtained. Furthermore, anion sometimes difficult to use due to their low boiling point. Such as chloride ion and Sulfate ion can be hardly taken into the inside of the produced titanium oxide powder and 0.133 As for the hydroxide of ammonium salt, for therefore, when a titanium-containing composite oxide pow example, choline and tetramethylammonium hydroxide (TMAH) are known and these are inexpensively available. der is produced, the intermingling of anion into the powder In particular, tetramethylammonium hydroxide is being used can be decreased. for electronic industry and is preferred because not only 0127. On the other hand, if the hydrolysis is performed in those reduced in impurities such as metal ion are available a neutral or basic Solution, the reaction rate increases and but also this hydroxide can be removed as a gas by under many nucleations occur in the initial stage, as a result, a going thermal decomposition at 135 to 140° C. titanium oxide Sol having bad dispersibility despite a small particle diameter is produced, causing vine-like aggregation 0.134. The barium calcium titanate powder of the present of powder. If a titanium-containing composite oxide powder invention can also be produced even by using an inexpen is produced by using Such a titanium oxide Sol as the raw sive inorganic compound Such as lithium hydroxide, Sodium material, the obtained powder may suffer from bad dispers hydroxide and potassium hydroxide. ibility despite a small particle diameter. In addition, anion 0.135 The base compound is not particularly limited and readily intermingles into the inside of the titanium oxide one of these base compounds may be used alone or two or powder and the removal of such anion in the Subsequent step more thereof may be mixed at an arbitrary ratio and used. is sometimes difficult. 0.136 The thus-produced barium calcium titanate powder 0128. The process for hydrolyzing a titanium salt in an has a small particle diameter, a narrow particle size distri acidic solution to obtain a titanium oxide Sol is not particu bution, excellent dispersibility, high crystallinity and excel larly limited as long as the solution can be kept acidic, but lent electric properties. Particularly, in this powder, the a process of using titanium tetrachloride as the raw material, impurities are less present and barium and calcium are performing the hydrolysis in a reactor equipped with a reflux solid-dissolved at an arbitrary ratio. This powder is shaped condenser, and keeping the Solution acidic by Suppressing into a dielectric porcelain, a pyro electric porcelain, a piezo the escape of chlorine generated there (JP-A-11-43327) is electric porcelain or a thin-film shaped article. preferred. 0.137 Such a porcelain or thin-film shaped article is used 0129. The concentration of the titanium salt in the acidic for capacitor materials, sensors and the like. solution is preferably from 0.01 to 5 mol/L. If the concen tration exceeds 5 mol/L, the reaction rate of hydrolysis 0.138. The barium calcium titanate powder may be used increases and a titanium oxide Sol with a large particle size after the barium calcium titanate powder alone or mixed and bad dispersibility may be obtained, whereas if it is less with additives, other materials and the like is formed into a than 0.01 mol/L, the concentration of the titanium oxide slurry or paste by using one or more solvent comprising obtained may decrease, giving rise to bad productivity. water, a known inorganic binder or a known organic binder. 0130. The method for charging the titanium oxide sol is 0.139. The electric properties of barium calcium titanate not particularly limited, but in order to obtain a barium powder can be evaluated by firing a disc shaped after adding calcium titanate with excellent dispersibility by preventing various additives Such as sintering aid to the powder or a aggregation of the titanium oxide Sol, the titanium oxide Sol thin-film product shaped after adding various additives to is preferably charged little by little into a reaction solution the slurry or paste containing the powder, under appropriate under heating and stirring resulting from charging a barium conditions and then measuring the fired body with use of an calcium salt at least in an amount of Saturated solubility to impedance analyzer or the like. a basic solution in which a basic compound is present. 0140. When a filler containing the barium calcium titan Examples of the method for charging the titanium oxide Sol ate powder is dispersed in at least one member selected from little by little include dropwise addition with use of a pump a thermosetting resin and a thermoplastic resin, a film with or the like, and injection into liquid. high dielectric constant can be obtained. 0131. In the present invention, a basic compound is 0.141. In the case of incorporating a filler other than contained in the basic Solution used as a reaction solution, and by virtue of this basic compound, the pH of the basic barium calcium titanate powder, one or more member Solution is kept to 10 or more. This basic compound is not selected from the group consisting of alumina, titania, particularly limited but is preferably a substance which Zirconia and tantalum oxide may be selected and used. becomes a gas through evaporation, Sublimation and/or 0142. The thermosetting resin and thermoplastic resin are thermal decomposition under atmospheric or reduced pres not particularly limited and a generally employed resin may Sure. The basic compound is preferably, for example, ammo be used, but suitable examples of the thermosetting resin nia, an organic amine having high solubility in water and include epoxy resin, polyimide resin, polyamide resin and having a small carbon number, or an organic base Such as bistriazine resin, and Suitable examples of the thermoplastic hydroxide of ammonium salt. resin include polyolefin resin, styrene-based resin and polya 0132 Among these, the hydroxide of ammonium salt is mide. more preferred, because when dissolved in water, this exhib 0.143. In order to uniformly disperse the barium calcium its high dissociation, acts as a strong base and does not titanate powder-containing filler in at least one member volatilize at the reaction. On the other hand, the ammonia selected from a thermosetting resin and a thermoplastic and organic amine having high solubility in water and resin, the filler is preferably dispersed in advance in a US 2007/02531.45 A1 Nov. 1, 2007

solvent or in a mixture of the above-described resin com heating temperature is set to the boiling point of the solvent position and a solvent to obtain a slurry. or less and the heating time may be prolonged according to 0144. The method for obtaining a slurry by dispersing the the heating temperature set. filler in a solvent or in a mixture of the resin composition and 0.149 FIG. 1 is a cross-sectional schematic view of a a solvent is not particularly limited but preferably contains multilayer ceramic capacitor as one example of the capaci a wet grinding step. tor. As shown in FIG. 1, the multilayer ceramic capacitor 1 0145 The solvent is not particularly limited and any comprises a stacked body 5 in which a dielectric layer 2 and Solvent may be used as long as it is a generally employed internal electrodes 3 and 4 are sequentially stacked, and solvent, but, for example, methyl ethyl ketone, toluene, ethyl external electrodes 6 and 7 fixed on the side surfaces of the acetate, methanol, ethanol, N,N-dimethylformamide, N.N- stacked body 5. The internal electrodes 3 and 4 each is dimethylacetamide, N-methylpyrrolidone and methyl cello exposed at one end to the side surface of the stacked body solve may be used individually or in combination of two or 5 and each one end is connected to the external electrode 6 more thereof. or 7. 0146 In order to obtain a slurry by dispersing the filler in 0150. The dielectric layer 2 is formed by solidifying and a solvent or in a mixture of the resin composition and a shaping the barium calcium titanate powder with use of a Solvent, the filler is preferably treated with a coupling agent. binder or the like, and the internal electrodes 3 and 4 each The coupling agent is not particularly limited and examples comprises, for example, Ni, Pd or Ag. The external elec thereof include a silane coupling agent, a titanate-based trodes 6 and 7 each comprises, for example, a sintered body coupling agent and an aluminate-based coupling agent. The of Ag, Cu or Ni, which is subjected to Ni plating. hydroxyl group of the coupling agent reacts with an active hydrogen on the Surface of the filler containing the barium 0151. The capacitor 1 shown in FIG. 1 is used, for calcium titanate powder of the present invention to cover the example, by packaging it, as shown in FIG. 2, on a circuit surface and therefore, dispersibility in a solvent becomes board 11 of a cellular phone 10. good. The hydrophobic group of the coupling agent may 0152 One example of the production method of the elevate the compatibility with the resin depending on the multilayer ceramic capacitor is described below. hydrophobic group selected. For example, in the case of using an epoxy resin as the resin, the coupling agent is 0153. A barium calcium titanate powder, a binder, a suitably a silane coupling agent in which any one of dispersant and water are mixed to produce a slurry. The monoamino, diamino, cationic styryl, epoxy, mercapto, slurry is preferably vacuum-deaerated in advance. anilino, ureido and the like is present in one functional 0154) This slurry is thinly coated on a substrate by a group, or a titanate-based coupling agent in which any one doctor blade method or the like and then heated to evaporate of phosphite, amino, diamino, epoxy, mercapto and the like water, whereby a dielectric layer mainly comprising a is present in one functional group. In the case of using a polyimide resin as the resin, the coupling agent is preferably barium calcium titanate powder is formed. a silane coupling agent in which any one of monoamino, 0.155 On this dielectric layer, a metal paste such as Ni, Pd diamino, anilino and the like is present in one functional and Ag is coated, another dielectric layer is stacked thereon, group, or a titanate-based coupling agent in which any one and a metal paste working out to the internal electrode is of monoamino, diamino and the like is present in one further coated. This step is repeatedly performed, whereby a functional group. One of these coupling agents may be used stacked body in which a dielectric layer and an internal alone, or two or more thereof may be mixed and used. electrode are sequentially stacked is obtained. The stacked 0147 The amount blended of the coupling agent is not body is preferably pressed to tightly contact the dielectric particularly limited and it may sufficient if a part or the entire layer and the internal electrode. of the barium calcium titanate powder is covered. However, 0156 Subsequently, the stacked body is cut into a capaci if the amount blended is too large, the coupling agent may tor size and fired at 1,000 to 1,350° C. After the firing, an remain unreacted and give an adverse effect, whereas if the external electrode paste is coated on the side surface of the amount blended is too small, the coupling effect may stacked body and fired at 600 to 850° C. Finally, the surface decrease. Therefore, the amount blended is preferably of the external electrode is subjected to Ni plating. selected to allow for uniform dispersion of the filler accord ing to the particle diameter and specific Surface area of the 0157. In this way, a multilayer ceramic capacitor 1 shown barium calcium titanate powder-containing filler and the in FIG. 1 is obtained. kind of the coupling agent. The amount of the coupling agent blended is preferably on the order of 0.05 to 20 mass % 0158. In the multilayer ceramic capacitor 1 obtained based on the barium calcium titanate powder-containing above, a barium calcium titanate with high dielectric con filler. stant as a preferred embodiment of the present invention is used for the dielectric material, so that the electrostatic 0148. In order to complete the reaction between the capacitance of the capacitor can be increased. Furthermore, hydrophilic group of the coupling agent and the active in the capacitor 1, a barium calcium titanate having a small hydrogen on the Surface of the barium calcium titanate particle diameter as a preferred embodiment of the present powder-containing filler, a step of heat-treating the slurry invention is used for the electric material, so that the formed is preferably provided. The heating temperature and thickness of the dielectric layer can be made small and in time are not particularly limited, but the heat-treatment is turn, the capacitor itself can be miniaturized. Also, by virtue preferably performed at 100 to 150° C. for 1 to 3 hours. of the decreased thickness of the dielectric layer, the elec When the boiling point of the solvent is 100° C. or less, the trostatic capacitance of the capacitor can be more increased. US 2007/02531.45 A1 Nov. 1, 2007

0159. This down-sized multilayer ceramic capacitor can minutes, thereby hydrolyzing titanium tetrachloride to be suitably used as a part of electronic devices, particularly obtain a titanium oxide Sol. The obtained titanium oxide sol portable devices including cellular phone. was dried at 110° C. and the crystal type was examined by 0160 The present invention is described in greater detail an X-ray diffraction apparatus (RAD-B, Rotor Flex, manu below by referring to Examples and Comparative Examples, factured by Rigaku Corporation), as a result, this titanium but the present invention is not limited to these Examples. oxide was found to be a brookite titanium oxide. 0171 Thereafter, 450 g of an aqueous 20 mass % tet (Method for Measuring Dielectric Constant: Measurement 1 ramethylammonium hydroxide Solution (produced by to 4) Sachem Showa, carbonate group concentration: 60 ppm or 0161 The dielectric constant of the obtained barium less) and 119.89 g of barium hydroxide octahydrate were calcium titanate was measured as follows. charged into a reactor with a reflux condenser and after 0162 Barium calcium titanate, MgO (high purity mag adjusting the pH to 14, the aqueous solution was boiled with nesium oxide 500-04R manufactured by Kyowa Chemical stirring. The titanium oxide sol obtained above was treated Industry Co., Ltd.), Y.O. (fine granulated powders of in an electrodialyzer to decrease the chloride ion to 500 ppm yttrium oxide UU-HP manufactured by Shin-Etsu Chemical and after precipitation and concentration, 213.1 g of the Co., Ltd.), SiO BaO—Li2O3 (a glass additive for LTCC resulting Sol having a titanium oxide concentration of 15 (Low Temperature Co-firing Ceramics) manufactured by mass % was added dropwise to the reactor at a rate of 7 Asahi Technoglass Corporation) were mixed at a ratio of g/min. While stirring as-is, boiling was maintained for 4 100:2:1.5:2 by molar ratio. The mixed powder of 0.3 g was hours. A part of the reaction solution was filtered, and uniaxially compacted by a metal mold with a diameter of 13 barium in the filtrate was measured by ICP spectrometry, as mm. The compact was then fired while being held at a result, the barium ion was 2 ppm, revealing that the temperatures shown in Table 1 in a nitrogen atmosphere for reaction proceeded until the barium ion decreased to 1/1,000 2 hours. of the amount charged. 0172 Subsequently, 1.48 g of calcium hydroxide (pro (Measurement 1) duced by Wako Pure Chemical Industries, Ltd., guaranteed 0163 The sintered body was obtained at the firing tem reagent) was charged into the reaction solution and while perature of 1080° C. stirring as-is, boiling was maintained for 6 hours. Calcium ion was extracted from a part of the reaction solution and (Measurement 2) measured by ICP spectrometry, as a result, the calcium ion 0164. The sintered body was obtained at the firing tem was 3 ppm, revealing that the reaction proceeded until the perature of 1120° C. calcium ion decreased to 1/1,000 of the amount charged. (Measurement 3) 0173 Thereafter, the reaction solution was filtered, and the obtained filter cake was dried at 300° C. for 5 hours to 0165. The sintered body was obtained at the firing tem obtain a dry powder. The ratio of the actual yield to the perature of 1060° C. theoretical yield calculated from the amounts of the titanium (Measurement 4) oxide, barium hydroxide and calcium hydroxide used for the reaction was 99.9%. 0166 The sintered body was obtained at the firing tem perature of 1040° C. 0.174 The dried powder was ground in a mortar and the specific Surface area of the powder was measured by the 0167 The size of the thus obtained sintered body was BET method and found t be 48 m/g. precisely measured, and a silver paste was coated on the sintered body. Then, electrodes were formed by baking the 0.175. This powder was evaluated by the above-described sintered body at 800° C. for 10 minutes in an air atmosphere X-ray diffraction apparatus. FIG. 3 shows the X-ray diffrac to obtain a single plate capacitor. tion spectrum at this evaluation. As shown in FIG. 3, a diffraction peak of the orthorhombic perovskite compound 0168 The area, thickness and weight of the capacitor was not observed and the content of orthorhombic perovs were measured and the sintered density thereof was calcu kite compound was 3 mol % or less. lated. 0176). Also, the Rietveld analysis was performed from the 0169. The capacitance of the capacitor was measured by X-ray diffraction intensity, as a result, the obtained powder HEWLETT PACKARD 4192ALF impedance analyzer at was found to be a Bacoso,CaoosTiO powder having Solid the frequency of 1 kHz and the temperatures of -55° C. to dissolved therein barium and calcium. 125°C., and the dielectric constant was calculated from the capacitance and the size of the sintered body. 0177. They determined from the a-axis length and the c-axis length was 1.0045, and formula (1) was satisfied. EXAMPLE 1. 0.178 The powder shape was enlargedly observed by a 0170 An aqueous solution containing titanium tetrachlo scanning electron microscope. FIG. 4 shows the results. ride (produced by Sumitomo Titanium Corp., purity: 99.9%) 0.179 Furthermore, the obtained sample was observed at a concentration of 0.25 mol/L was prepared. This aqueous through a transmission electron microscope (H-9000UHR, Solution was charged into a reactor with a reflux condenser manufactured by Hitachi, Ltd.). It was seen from the and heated to a temperature near the boiling point while elementary analysis by EDX that, as shown in FIG. 5, preventing escape of chloride ion and keeping the Solution barium and calcium were uniformly solid-dissolved in the acidic. The solution was kept at that temperature for 60 powder. US 2007/02531.45 A1 Nov. 1, 2007

0180. The amount of the carbonate group contained in the diameter when the accumulated volume reaches 95% is D3 powder was determined by using an infrared spectrometer and the maximum particle diameter is D4, D2/D1 was 0.6, (FTS6000, manufactured by BIORAD). Assuming that all D3/D1 was 1.6, and D4/D1 was 1.8. carbonate groups are barium carbonate or calcium carbon 0187 Furthermore, the barium calcium titanate powder ate, a carbonate group in an amount corresponding to about of Example 2 was observed through a transmission electron 1 mass % was detected. Incidentally, a sharp absorption peak microscope. It was seen from the elementary analysis by in the vicinity of 3,500 cm' assignable to the hydroxyl EDX that, as shown in FIG. 8, barium and calcium were group in the crystal lattice did not appear. uniformly solid-dissolved in the powder. EXAMPLE 2 0188 As shown in FIG. 9, the barium calcium titanate powder of Example 2 was observed by a transmission 0181. The powder obtained in Example 1 was charged electron microscope at a magnification of 250,000, but into an electric furnace (KDFP-90, manufactured by Denken defects ascribable to the elimination of hydroxyl group were Co., Ltd.) to fire the same. The firing treatment was per not observed. formed under the conditions that the temperature was elevated at a rate of 20° C./min and the powder was kept at 0189 Also, from the electron beam diffraction image, the 950° C. for 2 hours and thereafter, naturally cooled. In this barium calcium titanate powder of Example 2 was found to way, the barium calcium titanate powder of Example 2 was be a single crystal. obtained. 0.190 Table 1 shows the measurement result of the 0182. The specific surface area of the barium calcium dielectric constant. (Measurement 1) titanate powder of Example 2 was measured by the BET method and found to be 6.8 m/g. EXAMPLE 3 0183 FIG. 6 shows the X-ray diffraction spectrum of the 0191 The barium titanate calcium of Example 3 was barium calcium titanate powder after the heat treatment. As obtained by firing the powder obtained in Example 1 in the shown in FIG. 6, a peak of the orthorhombic perovskite same way as in Example 2 except that the powder was held compound was not observed and the content of the orthor at 1000° C. for 2 hours. hombic perovskite compound was 3 mol % or less. They 0.192 The specific surface area of the barium calcium (c/a) was 1.0081, and formula (1) was satisfied. titanate powder of Example 3 was 5.1 m/g. The y was 0184 Thereafter, the barium calcium titanate powder of 1.0093, and formula (1) was satisfied. Furthermore, D2/D1 Example 2 was measured on the phase transition point from determined by the image analysis method was 0.6, D3/D1 the orthorhombic system to the tetragonal system by using was 1.7 and D4/D1 was 1.8. a differential scanning calorimeter (manufactured by Seiko 0193 Table 1 shows the measurement result of the Instruments Inc.). The conditions were assumed Such that dielectric constant. (Measurement 1 and 2) the temperature was elevated at a rate of 10° C./min from –40° C. to 200° C., the powder was kept at 200° C. for 10 EXAMPLE 4 minutes, and the temperature was lowered at a rate of 10° C./min until -40°C. As a result, the phase transition point 0194 The barium calcium titanate powder of Example 4 from the orthorhombic system to the tetragonal system was was produced by the same operation as in Example 1 except -16°C. The barium calcium titanate powder of Example 2 that the amount of the barium hydroxide octahydrate was also measured on the phase transition point from the charged was 107.27 g and the amount of the calcium orthorhombic system to the tetragonal system by using a hydroxide charged was 4.45 g. differential scanning calorimeter (manufactured by Bruker AXS K.K., DSC320SA). The conditions were assumed such 0.195 The specific surface area of the obtained barium that the temperature was elevated at a rate of 10° C./min calcium titanate powder Example 4 was 49 m/g. A peak of from a room temperature to 100°C., the powder was kept at the orthorhombic perovskite compound was not observed in 100° C. for 10 minutes, and the temperature was lowered at the X-ray diffraction spectrum and the content of orthor a rate of 10°C/min until -100° C., and the temperature was hombic perovskite compound was 3 mol % or less. elevated at a rate of 10° C./min until 150° C. As a result, the 0196. Also, the Rietveld analysis was performed from the phase transition point from the orthorhombic system to the X-ray diffraction intensity, as a result, the obtained powder tetragonal system was -16° C. was found to be a BassoCaseTiO powder having Solid 0185. The barium calcium titanate powder of Example 2 dissolved therein barium and calcium. The y was 1.0048, was enlargedly observed by a scanning electron microscope. and formula (2) was satisfied. FIG. 7 shows the SEM photograph. 0197) Furthermore, the powder of Example 4 was observed by a transmission electron microscope at a mag 0186 The photograph shown in FIG. 7 was analyzed to nification of 250,000, but defects ascribable to the elimina measure the area of the barium calcium titanate powder, and tion of hydroxyl group were not observed. a sphere-reduced volume was determined. Similarly, the area by number of the barium calcium titanate powder was EXAMPLE 5 determined, and the particle size distribution was obtained. Assuming that the average particle diameter on the Volume 0198 The barium titanate calcium of Example 5 was basis as determined by the image analysis method is D1, the obtained by firing the powder obtained in Example 4 in the particle diameter when the volume accumulated from the same way as in Example 2 except that the powder was held smaller particle diameter side reaches 5% is D2, the particle at 1100° C. for 2 hours. US 2007/02531.45 A1 Nov. 1, 2007

0199 The specific surface area of the obtained powder of aqueous solution was boiled with stirring. Then, a titanium Example 5 was 5 m/g. A peak of the orthorhombic perovs oxide Sol was prepared in the same manner as in Example 1 kite compound was not observed in the X-ray diffraction and treated in an electrodialyzer to decrease the chloride ion spectrum and the content of orthorhombic perovskite com to 500 ppm and after precipitation and concentration, 213 g pound was 3 mol % or less. They was 1.0092, and formula of the resulting Sol having a titanium oxide concentration of (1) was satisfied. Also, D2/D1 determined by the image 15 mass % was added dropwise to the reactor at a rate of 7 analysis method was 0.6, D3/D1 was 1.8 and D4/D1 was g/min. While stirring as-is, boiling was maintained for 4 1.9. Furthermore, the powder was observed by a transmis hours. A part of the reaction solution was filtered, and sion electron microscope at a magnification of 250,000, but barium in the filtrate was measured by ICP spectrometry, as defects ascribable to the elimination of hydroxyl group were a result, the barium ion was 2 ppm, revealing that the not observed. reaction proceeded until the barium ion decreased to 1/1,000 0200 Table 1 shows the measurement result of the of the amount charged. dielectric constant. (Measurement 1) 0209 Thereafter, the same operation as in Example 1 except for the above-described operation was performed to EXAMPLE 6 produce the barium calcium titanate powder of Comparative 0201 The barium titanate calcium powder of Example 6 Example 1. was manufactured by performing a similar operation to that 0210. The specific surface area of the obtained powder of Example 1 except that an autoclave was used as a reactor was 38 m/g. FIGS. 10 and 11 each shows the X-ray vessel and the reaction temperature was set to 110° C. diffraction spectrum diagram of the powder. FIG. 11 is an enlarged view of FIG. 10. In FIG. 11, the peaks of the 0202 The specific surface area of the obtained barium orthorhombic perovskite compound are indicated by the calcium titanate powder of Example 6 was 43 m/g. A peak mark O. In this way, in the X-ray diffraction spectrum of the of the orthorhombic perovskite compound was not observed barium calcium titanate of Comparative Example 1, peaks of in the X-ray diffraction spectrum and the content of orthor the orthorhombic perovskite compound were observed. hombic perovskite compound was 3 mol % or less. From this, the content of the orthorhombic perovskite com 0203 Furthermore, the Rietveld analysis was performed pound was found to exceed 3 mol%. from the X-ray diffraction intensity, as a result, the obtained powder was found to be a Baoso Caos TiO powder hav COMPARATIVE EXAMPLE 2 ing solid-dissolved therein barium and calcium. They was 0211 The barium titanate calcium of Comparative 1.0038, and formula (2) was satisfied. Example 2 was obtained by firing the powder obtained in 0204 Furthermore, the powder of Example 6 was Comparative Example 1 in the same way as in Example 2 observed by a transmission electron microscope at a mag except that the powder was held at 1000° C. for 2 hours. nification of 250,000, but defects ascribable to the elimina 0212. The specific surface area of the obtained powder tion of hydroxyl group were not observed. was 5.1 m/g. FIGS. 12 and 13 each shows the X-ray diffraction spectrum diagram of the powder. FIG. 13 is an EXAMPLE 7 enlarged view of FIG. 12. In FIG. 13, the peaks of the 0205 Barium titanate calcium of Example 7 was orthorhombic perovskite compound are indicated by the obtained by firing the powder obtained in Example 6 in the mark O. In this way, also in the X-ray diffraction spectrum same way as in Example 2 except that the powder was held of the barium calcium titanate of Comparative Example 2, at 880° C. for 2 hours. peaks of the orthorhombic perovskite compound were 0206. The specific surface area of the obtained powder of observed. From this, the content of the orthorhombic per Example 7 was 10 m/g. A peak of the orthorhombic ovskite compound was found to exceed 3 mol%. They was perovskite compound was not observed in the X-ray dif 1.0077, and formula (1) was not satisfied. Furthermore, the fraction spectrum and the content of orthorhombic perovs phase transition point from the orthorhombic system to the kite compound was 3 mol % or less. They was 1.0067, and tetragonal system was measured and found to be -15° C. formula (2) was satisfied. Also, D2/D1 determined by the D2/D1 determined by the image analysis method was 0.4, image analysis method was 0.8, D3/D1 was 1.5 and D4/D1 D3/D1 was 2.0 and D4/D1 was 2.5. was 1.6. Furthermore, the powder was observed by a trans 0213 Table 1 shows the measurement result of the mission electron microscope at a magnification of 250,000, dielectric constant. (Measurement 1 and 4) but defects ascribable to the elimination of hydroxyl group were not observed. COMPARATIVE EXAMPLE 3 0207 Table 1 shows the measurement result of the 0214) The barium calcium titanate powder of Compara dielectric constant. (Measurement 3) tive Example 3 was produced by the same operation as in Comparative Example 1 except that the amount of the COMPARATIVE EXAMPLE 1. barium hydroxide octahydrate charged was 107.27 g and the 0208 An aqueous 20 mass % tetramethylammonium amount of the calcium hydroxide charged was 4.45 g. hydroxide solution (produced by Sachem Showa, carbonate 0215. The specific surface area of the obtained powder group concentration: 60 ppm or less) (450 g), 119.89 g of was 38 m/g. In the X-ray diffraction spectrum of this barium hydroxide octahydrate and 1.48 g of calcium powder, a peak of the orthorhombic perovskite compound hydroxide octahydrate were charged into a reactor with a was observed. From this, the content of the orthorhombic reflux condenser and after adjusting the pH to 14, the perovskite compound was found to exceed 3 mol%. US 2007/02531.45 A1 Nov. 1, 2007

COMPARATIVE EXAMPLE 4 0223 Since the sintered densities of the barium titanate calcium of Comparative Examples 2 and 4 were lower 0216) The barium calcium titanate powder of Compara (90-92%), the temperature characteristics did not satisfied tive Example 4 was produced by performing the firing in the the X7R of the EIA standard (“poor) when the firing same manner as in Example 2 except that the powder temperature was 1080° C. On the other hand, the tempera obtained in Comparative Example 3 was kept at 1,020° C. ture characteristics satisfied the X7R of the EIA standard for 2 hours. (“good') when the firing temperature was 1040° C., how 0217. The specific surface area of the obtained powder ever, the dielectric constants were lower (1000-1100). was 5.3 m/g. Also, a peak of the orthorhombic perovskite compound was observed in the X-ray diffraction spectrum of INDUSTRIAL APPLICABILITY this powder, and the content of the orthorhombic perovskite 0224. The barium calcium titanate of the present inven compound was found to exceed 3 mol%. They was 1.0081, tion has a remarkable effect that a fine barium calcium and formula (1) was not satisfied. Furthermore, D2/D1 titanate powder having excellent dispersibility, reduced determined by the image analysis method was 0.3, D3/D1 impurities and high crystallinity and being Solid-dissolved at was 2.2 and D4/D1 was 2.8. an arbitrary ratio, and a production process thereof are provided. 0218 Table 1 shows the measurement result of the dielectric constant. (Measurement 1 and 4) 0225. This barium calcium titanate powder and a slurry or paste containing the powder can exert excellent electric TABLE 1. properties, and a dielectric material, a piezoelectric material, a pyroelectric material or the like having excellent perfor Firing Sintered Dielectric mance, such as porcelain, thin film and dielectric film, can Temperature Density Constant Temperature be obtained therefore. Furthermore, by using such a material (° C.) (%) at 25° C. Characteristics for an electronic device, a down-sized lightweight electronic Example 2 O8O 95 300 good device can be realized. The dielectric film has excellent (Measurement 1) Example 3 O8O 95 400 good electric property and therefore, even when formed into a thin (Measurement 1) film, the dielectric film can exert excellent properties and Example 3* 120 95 800 good can be applied to an embedded capacitor or the like. Use of (Measurement 2) this capacitor in electronic devices such as cellular phone or Example 5 O8O 95 200 good (Measurement 1) digital camera is very effective for the realization of a Example 7 O60 95 200 good down-sized, lightweight and high-performance device. (Measurement 3) Comparative O8O 92 400 poor 1. A barium calcium titanate represented by the compo Example 2 (Measurement 1) sitional formula: (Baix Cax). TiO, (wherein 0

and the maximum particle diameter is D4, D3/D1 is from 1 15. The process for producing a barium calcium titanate to 1.8 and D4/D1 is from 1 to 2. as claimed in claim 9, wherein the titanium oxide is a 7. The barium calcium titanate as claimed in claim 1, titanium oxide Sol obtained by hydrolyzing a titanium com which is a powder having a specific surface area D of 5 to pound in an acidic solution. 100 m2/g. 16. The process for producing a barium calcium titanate 8. The barium calcium titanate as claimed in claim 1, as claimed in claim 9, wherein the basic compound is a wherein X in the compositional formula is 0.05s X-0.2. Substance which undergoes vaporization by any one or more 9. A process for producing a barium calcium titanate, means of evaporation, Sublimation and thermal decomposi comprising a step of synthesizing a barium titanate by tion under atmospheric pressure or reduced pressure. charging a barium hydroxide and a titanium oxide into a 17. The process for producing a barium calcium titanate basic compound-containing basic Solution at a pH of 10 or as claimed in claim 9, wherein the basic compound is an more and allowing the reaction to proceed, a step of syn organic base compound. thesizing a barium calcium titanate by charging a calcium 18. The process for producing a barium calcium titanate hydroxide and allowing the reaction to proceed, and a step as claimed in claim 9, wherein the basic compound is of vaporizing and removing the basic compound. tetramethylammonium hydroxide. 10. The process for producing a barium calcium titanate 19. A dielectric material comprising the barium calcium as claimed in claim 9, wherein the molar ratio of the barium titanate claimed in claim 1. hydroxide and the calcium hydroxide is set to from 1:0 to 20. A paste comprising the barium calcium titanate 0.8:0.2, the amount of the titanium oxide is set to from 0.98 claimed in claim 1. to 1.02 times the total molar amount of the barium hydroxide 21. A slurry comprising the barium calcium titanate and the calcium hydroxide, and these barium hydroxide, claimed in claim 1. calcium hydroxide and titanium oxide are reacted in a basic 22. A thin-film shaped product comprising the barium Solution to produce a barium calcium titanate. calcium titanate claimed in claim 1. 11. The process for producing a barium calcium titanate as 23. A dielectric porcelain produced by using the barium claimed in claim 9, wherein the reaction in the step of calcium titanate claimed in claim 1. synthesizing a barium titanate is continued until the amount 24. A pyroelectric porcelain comprising produced by of barium ion remaining in the basic solution becomes 1/100 using the barium calcium titanate claimed in claim 1. or less of the amount charged, and the reaction in the step of 25. A piezoelectric porcelain comprising produced by synthesizing a barium calcium titanate is continued until the residual amount of calcium ion becomes 1/100 or less of the using the barium calcium titanate claimed in claim 1. amount charged. 26. A capacitor comprising the dielectric porcelain 12. The process for producing a barium calcium titanate claimed in claim 23. as claimed in claim 9, wherein after the step of removing the 27. An electronic device comprising at least one member basic compound, the barium calcium titanate is heat-treated selected from the group consisting of the thin-film shaped at 350 to 1200° C. product, the porcelain and the capacitor claimed in claim 22. 13. The process for producing a barium calcium titanate 28. A sensor comprising one species or two or more as claimed in claim 9, wherein in the process from the species of the thin-film shaped product or porcelain claimed synthesis of a barium titanate to the synthesis of a barium in claim 22. calcium titanate, the concentration of a carbonate group in 29. A dielectric film comprising the barium calcium the reaction solution is controlled to be from 0 to 500 ppm titanate claimed in claim 1. in terms of CO. 30. A capacitor produced by using the dielectric film 14. The process for producing a barium calcium titanate claimed in claim 29. as claimed in claim 9, wherein the titanium oxide contains a brookite crystal.