SYNTHESIS OF Bi2NiTa2O9 WITH A PYROCHLORE-TYPE STRUCTURE

Nickel pyrochlore of the composition Bi2NiTa2O9 was synthesized by the solid-phase reaction method (sp. gr. Fd-3m, a = 10.5238 Å). The process of phase formation of nickel-containing bismuth tantalate Bi2NiTa2O9 with a pyrochlore structure is investigated. The pyrochlore phase synthesis reaction is described by the interaction of orthorhombic bismuth orthotantalate and nickel oxide. Synthesis proceeds mainly at temperatures above 900 °С. The duration of calcination of the preparations leads to the coalescence of grains with the formation of larger particles. The calcination temperature did not significantly affect the microstructure of the samples. The samples are characterized by a porous dendritic microstructure with a grain size of 0.5 – 1.0 µm. The optimal conditions for obtaining pure pyrochlore can be considered a temperature of 1050 °С and calcination time of 15 hours.