Process for preparing crystalline mixed metal oxides

Claim 2

A process for preparing crystalline mixed metal oxides having simultaneously a narrow particle size distribution and low surface area of the formula: ABO.sub.3 wherein, A is metal cation selected from Ba, Sr, Ca, Mg, Pb and Nd and mixtures thereof; and B is metal cation selected from Ti, Zr, Nb, Hf, Zn and Sn and mixtures thereof which comprises the steps of: (a) simultaneously and continuously mixing an organometallic compound, mixture of organometallic compounds or a hydrolyzable system, of the structure BL n , where B is as defined above, L is a hydrolyzable group, or a combination of such groups, selected from alkoxy, aryloxy, aminoalkoxy, acetoxy, acetoacetonyl, chlorides, nitrates, and acetates, and n is 2 or 4 with a solution of a compound, or a mixture of compounds, of the general structure AX y , where A is as defined above, X is an anion, or combination of anions, selected from hydroxide, chloride, nitrate and acetate, and y is 2 or 3 in an alkaline, high turbulence energy environment characterized by a turbulence intensity greater than 9×10 6 cm/sec 3 ; (b) crystallizing the reaction product; and (c) recovering crystals wherein 90% of particles are greater than 0.2 μm in size up to about 1.0 μm in size, the surface area is less than 15 m 2 /g and the A/B mole ratio is from 0.990 to 1.020.

Claim 3

The process of claim 1 wherein the solution of A cations is an aqueous solution.

Claim 4

The process of claim 1 wherein the solution of A cations is a non-aqueous solution.

Claim 5

The process of claim 1, 2, or 3 in which the organometallic compounds BLn are premixed with a nonionic surfactant to form a first ingredient stream which is reacted with the solution of compounds AX y as a second ingredient stream by mixing said streams simultaneously and continuously in a high turbulence energy environment.

Claim 6

The process of claim 4 wherein said mixing comprises pumping said ingredient streams simultaneously through a coaxial jet mixer.

Claim 7

The process of claim 4 wherein said organometallic compound BL n is tetrabutyl titanate and said surfactant is an ethoxylated alkylphenol.

Claim 8

A process for preparing crystalline barium titanate having 90% of the particles greater than 0.2 μm in size up to about 1.0 μm in size, and a surface area of less than about 15 m 2 /g which comprises the steps of: (a) reacting tetrabutyl titanate as a first ingredient stream with a solution of barium hydroxide as a second ingredient stream at a temperature of 80°-85° C. in a high turbulence energy environment comprising pumping said ingredient streams simultaneously through a coaxial jet mixer, said environment characterized by a turbulence intensity greater than 9×10 6 cm/sec 3 to form a slurry and discharging said slurry into an alkaline heel of water; (b) crystallizing said slurry by heating under reflux with continuous agitation for at least about 6 hours to no more than 48 hours; and (c) recovering said crystals.

Claim 9

A process for preparing crystalline barium titanate having 90% of the particles greater than 0.2 μm in size up to about 1.0 μm in size, and a surface area of less than about 15 m 2 /g which comprises the steps of: (a) reacting tetrabutyl titanate as a first ingredient stream with a solution of barium hydroxide as a second ingredient stream at a temperature of 80°-85° C. in a high turbulence energy environment comprising pumping said ingredient streams simultaneously through a coaxial jet mixer, said environment characterized by a turbulence intensity greater than 9×10 6 cm/sec 3 to form a slurry and discharging said slurry into an alkaline heel of water; (b) crystallizing said slurry by heating under reflux with continuous agitation for at least about 6 hours to no more than 48 hours; and (c) recovering said crystals.

Claim 10

A chemically homogeneous crystalline mixed metal oxides having a narrow particle size distribution and low surface area of the formula: ABO.sub.3 wherein, A is metal cation selected from Ba, Sr, Ca, Mg, Pb and Nd and mixtures thereof; and B is metal cation selected from Ti, Zr, Nb, Hf, Zn and Sn and mixtures thereof which are prepared by a process comprising the steps of: (a) simultaneously and continuously reacting an organometallic compound, or mixture of organometallic compounds, of the general structure BL n where B is as defined above, L is a hydrolyzable group, or combination of such groups, selected from alkoxy, aryloxy, aminoalkoxy, acetoxy, and acetoacetonyl, and n is 2, 4, or 5 as a first ingredient stream with a solution of a compound, or a mixture of compounds, of the general structure AX y , where A is as defined above, X is an anion, or a combination of anions, selected from hydroxide, chloride, nitrate and acetate, and y is 2 or 3 in an alkaline, high turbulence energy environment comprising pumping said ingredient streams simultaneously and continuously through a coaxial jet mixer characterized by a turbulence intensity greater than 9×10 6 cm/sec 3 ; (b) crystallizing the reaction product for at least 6 hours to no more than 48 hours; and (c) recovering crystals wherein 90% of particles are greater than 0.2 μm in size up to about 1.0 μm in size, a surface area of less than about 15 m 2 /g and an A/B mole ratio in the range of about 0.990 to about 1.020.

Claim 11

A chemically homogeneous crystalline mixed metal oxides having a narrow particle size distribution and low surface area of the formula: ABO.sub.3 wherein, A is metal cation selected from Ba, Sr, Ca, Mg, Pb and Nd and mixtures thereof; and B is metal cation selected from Ti, Zr, Nb, Hf, Zn and Sn and mixtures thereof which are prepared by a process comprising the steps of: (a) simultaneously and continuously reacting an organometallic compound, or mixture of organometallic compounds, of the general structure BL n where B is as defined above, L is a hydrolyzable group, or combination of such groups, selected from alkoxy, aryloxy, aminoalkoxy, acetoxy, and acetoacetonyl, and n is 2, 4, or 5 as a first ingredient stream with a solution of a compound, or a mixture of compounds, of the general structure AX y , where A is as defined above, X is an anion, or a combination of anions, selected from hydroxide, chloride, nitrate and acetate, and y is 2 or 3 in an alkaline, high turbulence energy environment comprising pumping said ingredient streams simultaneously and continuously through a coaxial jet mixer characterized by a turbulence intensity greater than 9×10 6 cm/sec 3 ; (b) crystallizing the reaction product for at least 6 hours to no more than 48 hours; and (c) recovering crystals wherein 90% of particles are greater than 0.2 μm in size up to about 1.0 μm in size, a surface area of less than about 15 m 2 /g and an A/B mole ratio in the range of about 0.990 to about 1.020.

Claim 12

The crystalline mixed metal oxide of claim 8 which is barium titanate or strontium titanate.

Claim 13

The crystalline mixed metal oxide of claim 9 which is doped with one or more ions selected from Nd, Nb, Zn and Zr.

Claim 14

The process of claim 1 wherein the crystalline mixed metal is a solid solution of barium titanate, barium zirconate and barium zinc niobate; the hydrolyzable system is a mixture comprising anhydrous zinc chloride, niobium (V) Chloride, zirconium-propoxide and tetrabutyl titanate, and the alkaline earth metal hydroxide is barium hydroxide.

Claim 15

The crystalline mixed metal oxide of claim 8 is a solid solution of barium titanate, barium zirconate and barium zinc niobate.