Low-Temperature Synthesis of K–Ba–Bi–O Oxides in KOH Solution

Abstract

The reaction of KBiO3–δ with Ba2+ ions at a Ba : Bi ratio of 0.5‒1.6 (mol.) in a 10 M. KOH solution under reflux (~140°C) has furnished oxides, which composition and structure have been studied by X-ray diffraction, energy dispersive X-Ray, and chemical analysis. Pseudo cubic (а = 4.271‒4.285 A) perovskite-like phases of barium‒bismuth(III,V)‒potassium oxides with insignificant impurity of sodium have been formed in the KBiO3–δ‒Ba2+‒OH–‒H2O system during 1 h. The products have been characterized by an average oxidation state of bismuth –Bi = 4.36‒4.59. Barium content in the resulting oxides has increased with an increase in its concentration in the charge. According to the Ba–Bi ratio, the resulting phases can be classified as non-superconducting oxides of homologous series МxBamBim+nOy (x <n), МxBamBim+nOy, and (М, Ba)m+nBimOy (m = 1, 2, ...; n = 0, 1, 2, ...), M = K, Na.