COMPOUNDS OF TANTALUM PENTOXIDE AND NIOBIUM PENTOXIDE Russian patent published in 2002 - IPC

FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to novel compounds of tantalum and niobium and methods of their synthesis. In the first vessel ammonia solution and tantalum or niobium fluoride compounds are mixed at pH 6-9.5, temperature is 30-95 C for 0.03-2 h and then the mixture is transferred from the first vessel to the second one. Temperature and contact time in the second vessel are similar with those in the first vessel, pH 8-9.5. Precipitation can be continued in the third vessel. Tantalum or niobium hydrated oxide is separated from a solution. For synthesis of tantalum pentoxide the obtained precursor is calcinated at 750 C. For synthesis of niobium pentoxide the obtained precursor is calcinated at 650 C. Value VET surface of niobium pentoxide powder is less 2 m²/g and value of thickened volume density is above 1.8 g/cm³ or VET value is above 2 m²/g and value of thickened volume density is less 1.8 g/cm³. Value VET surface of tantalum pentoxide powder is less 3 m²/g and value of thickened volume density is above 3 g/cm³ or value VET is above 3 m²/g and value of thickened volume density is less 3 g/cm³. A precursor of tantalum or niobium pentoxide shows line of d-values: 6 ± 0.3; 3 ± 0.2; 1.8 ± 0.1. Fluoride content in a precursor is less 500 million parts. Invention provides synthesis of particles of definite sizes. EFFECT: new compounds indicated above, valuable properties. 7 cl, 1 tbl, 17 dwg, 10 ex