THERMAL SYNTHESIS OF BARIUM AND BARIUM-STRONTIUM METANIOBATES BY USING A COPRECIPITATION METHOD.

Article abstract of DOI:10.1007/BF02105289

The authors present a new, non-traditional method for the synthesis of barium metaniobate, BaNb//2O//6, and of a mixed barium-strontium metaniobate, Ba//0//. //2//9Sr//0//. //7//1Nb//2O//6, through the thermal decomposition of coprecipitation products. The conditions of quantitative precipitation of the metals as niobic acid and barium or barium-strontium oxalate were established. The mechanism of thermal decomposition of the coprecipitate was deduced from differential thermal analysis and X-ray diffraction date. Barium metaniobate forms at 470 degree C, below the temperature required in the synthesis based upon the solid-state reaction between Nb//2O//5 and BaCO//3 (1100 degree C). The mixed barium-strontium compound is formed at 700 degree C, below the 1100 degree C used in the reaction between Nb//2O//5, BaCO//3 and SrCO//3.