An improved process for preparing crystalline mixed metal oxides, such as barium titanate, in which an organometallic compound is reacted simultaneously and continuously with a solution of a divalent metal ion in an alkaline high turbulence energy environment, the reaction product is crystallized, and the crystals are isolated and may be calcined.

Process for preparing crystalline mixed metal oxides

The present invention relates to a variety of dispersible doped multi-component BaTiO 3 based powder compositions. The primary particles of each of the products are substantially spherical, have sizes in the range of 0.05 to 0.4 microns and have narrow size distributions. Further, the compositions of the primary particles, forming each powder, are comparable. The amount of dopant oxide or oxides contained in the powder composition ranges from between greater than 1 to 10 mole percent. Regardless of the dopant or dopants utilzied, all the powder compositions of the present invention are identified by the same unique morphological characteristics.

Doped BaTiO3 based compositions

Barium titanate based dielectric compositions having the general formula Ba.sub.(1-x-x'-x") Pbx Cax' Srx" Ti .sub.(1-y-y'-y") Sny Zry' Hfy" O3, wherein x, x', x" and y, y', y" represent mole fractions of the divalent and tetravalent cations and x and x' have independent value greater than 0.01 and less than 0.3 and x", y, y' and y" have independent values greater than zero and less than 0.3, such that the sum (x+x'+x") is greater than 0.01 and less than 0.4 and the sum (y+y'+y") does not exceed 0.4. Regardless of the specific composition selected, the products of the invention have a mean primary particle size in the range of 0.05 to 0.4 microns with a very narrow particle size distribution. The products are dispersible so that the mean particle size determined by image anaylsis and by sedimentation are comparable.

Barium titanate powders

It is an object of the present invention to provide an inorganic dielectric powder used for a composite dielectric material, the inorganic dielectric powder having high filling properties and expressing a high dielectric constant when used as a composite dielectric. It is another object of the present invention to provide a composite dielectric material having a high dielectric constant, the composite dielectric material being used for dielectric layers of electronic components, such as printed circuit boards, semiconductor packages, capacitors, antennae for radio frequencies, and inorganic electroluminescent devices. In an inorganic dielectric powder according to the present invention used for a composite dielectric material mainly containing a polymeric material and the inorganic dielectric powder, the inorganic dielectric powder includes perovskite compound oxide particles in which a subcomponent element is dissolved in barium titanate particles, wherein the perovskite compound oxide particles are prepared by wet-reaction of a titanium compound and a barium compound with a compound containing the subcomponent element and then calcining the resulting reaction product.

Inorganic dielectric powder for composite dielectric material and composite dielectric material

PURPOSE: To obtain fine particles of compound bismuth oxide having uniform compsn. and high purity by allowing ≥ two kinds of alkoxide cong. Bi alkoxide to react with each other and hydrolyzing the reaction product and calcining the hydrolyzed product thereafter. CONSTITUTION: Bi alkoxide is mixed with at least one kind of alkoxide of Ba, Sr, Ca, Pb and/or Mo, W, Nb, Ta, Ti, etc. in an org. solvent (e.g. benzene) at 0W100°C to cause reaction. Decarboxylated distilled water is added to the soln. of the reaction product at 0W100°C, or steam is blown out of a pressurized vessel at 100W200°C to contact with the reaction product and to hydrolyze the reaction product, to obtn. powdery white precipitate. Then, the precipitate is filtered and dried, and calcined then at ≥600°C and < an initiating temp. of decomposition of the compound oxide. Thus, a compound Bi oxide having high purity contg. ≤0.1wt% impurity and 0.01W0.1 micron particle size being expressed by the formula (where A is Ba, Sr, Ca, Pb; B is Mo, W, when n=1; Nb, Ta, when n=2; Nb, Ti, etc. when n=3). COPYRIGHT: (C)1986,JPO&Japio

Preparation of compound bismuth oxide

PURPOSE: To manufacture dielectric powder giving a dense thick film porcelain capacitor almost free from defects by dropping a water-isopropyl alcohol mixed soln. into a soln. of specified 3 kinds of metallic alkoxides in isopropyl alcohol. CONSTITUTION: To isopropyl alcohol are added 48.50W49.92mol% barium dialkoxide, 45.5W49.78mol% titanium tetraalkoxide and 0.3W6mol% tantalum pentaalkoxide. The amount of the isopropyl alcohol is ≥5 times the total amount of the alkoxides by weight. They are stirred at 40W85°C to dissolve the alkoxides. The resulting soln. is kept at 40W85°C, a water-isopropyl alcohol mixed soln. having 1:10W2:1 weight ratio is dropped into said soln. under stirring, and Ta doped BaTiO 3 is precipitated by aging at 40W85°C. The precipitate is separated by filtration, dried, and heated to 400W1,000°C to obtain dielectric powder having ≥1,500 dielectric constant at room temp. and giving a small-sized thick film porcelain capacitor of a large capacity. The dielectric strength of the capacitor is ≥150V when the film thickness is regulated to 10μm. COPYRIGHT: (C)1984,JPO&Japio

Yoichiro Yokoya

Papers

Manufacture of dielectric powder for thick film