Method for preparing high-purity spherical niobium oxide by peroxidizing precipitation

Abstract

The invention discloses a method for preparing high-purity spherical niobium oxide by peroxidizing precipitation, which comprises the steps of: adding hydrogen peroxide H2O2 and liquid ammonia into a fluooxycolumbic acid solution H2NbOF5 to obtain (NH4)3NbO8 crystals; and roasting the crystals at a controlled temperature to obtain niobium oxide having a corresponding phase state and a granularity of 0.3-1 mum. According to the method disclosed by the invention, ammonium niobate crystals which are obtained from precipitation process are free from package, adsorption, and impurities and filtered easily. Consequently, high product purity is obtained in a case of the same raw materials and technological conditions; the ammonium niobate is then roasted at 150-1300 DEG C to obtain fluorine-free niobium oxide which is obviously spherical, uniform in particle and has the granularity of 0.3-1 mum; and niobium oxide at alpha, beta and gamma phase states can be obtained by controlling the roasting temperature according to application requirements. The method disclosed by the invention leaves out washing, drying as well as grinding and sieving procedures, saves plenty of manpower, material resources and energy sources.

Description

technical field [0001] The invention relates to a method for preparing spherical niobium oxide, in particular to a method for preparing high-purity spherical niobium oxide by using a peroxide precipitation process. Background technique [0002] The optimal particle size control of niobium hydroxide precipitation is a major problem in the manufacturing technology of high-performance functional ceramics. It belongs to the high-tech research and development supported by the state and is an important part of meeting the needs of large-capacity laminated ceramic capacitors and tantalum-niobium artificial crystals. The existing preparation technology is: precipitating the oxyfluoroniobic acid solution obtained by solvent extraction with ammonia to obtain amorphous flocculent niobium hydroxide slurry (particle size 1-3 μm), after filtering and washing, drying, Roasting, grinding and sieving to obtain niobium pentoxide. Its precipitation reaction mechanism is: H 2 Nb 5 +5NH 3 +4...

AI Technical Summary

Problems solved by technology

[0004] The major problems existing in the existing niobium hydroxide precipitation technology are: (1) the gained precipitate is amorphous floc or agglomerate, particle is thick, and the quality is low; (2) after precipitation and slurry filtration, a large amount of Fluorine washing with deionized water, however, can still cause lithium niobate crystal quality problems from time to time

Therefore, the product obtained by precipitation has coarse particles and low density, which is not suitable for the requirements of ceramic capacitor grade products (in July 1991, the Tokyo Institute of Technology in Japan first proposed the average particle size requirement of niobium oxide based on the application of niobium oxide in large-capacity laminated ceramic capacitors 0.32μm); in addition, the precipitates tend to aggregate and form "clusters" to wrap the mother liquor, thus affecting the purity of the final product