TANTALATE DISPERSION AND TANTALATE COMPOUND

Abstract

Provided is a novel tantalate dispersion containing no hardly-volatile organic component and having high dispersibility in water, the tantalate dispersion containing tantalum or/and tantalate and amine in water, the tantalate dispersion having an intensity ratio (5.5°/29°) of an intensity at 2θ = 5.5° to an intensity at 2θ = 29° being 1.00 or more in an X-ray diffraction pattern obtained by subjecting a powder obtained by drying the tantalate dispersion to powder X-ray diffraction measurement using CuKα rays.

Description

Claims

1. A tantalate dispersion comprising tantalum or/and tantalate and amine in water, the tantalate dispersion having an intensity ratio (5.5°/29°) of an intensity at 2θ = 5.5° to an intensity at 2θ = 29° being 1.00 or more in an X-ray diffraction pattern obtained by subjecting a powder obtained by drying the tantalate dispersion to powder X-ray diffraction measurement using CuKα rays.

2. The tantalate dispersion according to claim 1, comprising 0.01% by mass to 30% by mass of amine.

3. The tantalate dispersion according to claim 1, comprising 0.01% by mass to 40% by mass of tantalum in terms of Ta2O5.

4. The tantalate dispersion according to claim 1, having a transmittance at 400 nm being 40% or more.

5. The tantalate dispersion according to claim 1, wherein 30 g of the tantalate dispersion (25° C.) adjusted to a concentration containing 9% by mass of tantalum in terms of Ta2O5 is added with 30 mL of a sodium hydroxide aqueous solution (25° C.) having a concentration of 2.2% by mass while stirring and then stirred for 15 minutes after the addition to form a reaction liquid, and the reaction liquid is added with 100 mL of ethanol to form a precipitate composed of Na8Ta6O19·15H2O.

6. The tantalate dispersion according to claim 1, wherein 30 g of the tantalate dispersion (25° C.) adjusted to a concentration containing 9% by mass of tantalum in terms of Ta2O5 is added with 30 mL of a potassium hydroxide aqueous solution (25° C.) having a concentration of 3% by mass while stirring and then stirred for 15 minutes after the addition to form a reaction liquid, and the reaction liquid is added with 100 mL of ethanol to form a precipitate composed of K8Ta6O19·16H2O.

7. A method for producing a tantalate dispersion comprising adding a tantalum salt solution to an amine aqueous solution to obtain a primary reaction liquid (referred to as “primary neutralization”), adding the primary reaction liquid to ammonia water to obtain a secondary reaction solution (referred to as “secondary neutralization”), washing a tantalum-containing precipitate formed in the secondary reaction solution, and mixing the washed tantalum-containing precipitate with amine and water to produce a tantalate dispersion.

8. The method for producing a tantalate dispersion according to claim 7, wherein in the primary neutralization, the tantalum salt solution is added to an amine aqueous solution containing amine equivalent to or more than fluorine contained in the tantalum salt solution in terms of molar ratio.

9. The method for producing a tantalate dispersion according to claim 7, wherein in the secondary neutralization, the primary reaction liquid is added to ammonia water containing 7.5 times or more ammonia than fluorine contained in the primary reaction liquid in terms of molar ratio.

10. A tantalate compound having an intensity ratio (5.5°/29°) of an intensity at 2θ = 5.5° to an intensity at 2θ = 29° being 0.90 or more in an X-ray diffraction pattern, as measured by powder X-ray diffraction using CuKα rays.

11. The tantalate compound according to claim 10, wherein a part or the whole of the tantalate compound is an ammonium salt.

12. The tantalate compound according to claim 10, having a polyoxometalate structure.