SYNTHESIS OF OXYNITRIDE PEROVSKITES [AZRXTA1-XO2-X, A=CA, SR, BA AND S-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1](XN1)

Solid solution perovskite phases AZrxTa1-xO2+xN1-x, with A = Ca, Sr, B a and 0 less-than-or-equal-to x less-than-or-equal-to 1 have been synt hesised by ammonolysis of mixtures of Ta-Zr gels and ACO3. The gels we re made by the sol-gel technique using TaCl5 and Zr-n-propoxide as pre cursors. The perovskite phases have been characterised by X-ray powder diffraction and elemental analysis for one composition from each subs ystem has been performed. The Ca compounds were found to be orthorhomb ic for all x. The orthorhombic GdFeO3 type perovskite structure was ve rified for the composition CaZr0.52Ta0.48O2.52N0.48 by a Rietveld refi nement to R(F) = 2.3 %, using CuKalpa1 X-ray powder diffractometer dat a. According to X-ray powder diffraction data, the Sr compounds are or thorhombic for x greater-than-or-equal-to 0.60 and cubic for lower x v alues. The Ba compounds were found to be cubic for all x.