The influence of the additive BaGeO3 on BaSnO3 ceramics

DTA, XRD and sintering investigations of the system BaSnO3–BaGeO3, prepared by a mixed-oxide method, are described herein. The melting temperature of this system is about 1270 ± 5 °C. We find a partial solubility of BaGeO3 into BaSnO3 of the order of 6–7 mol%. Up to 50 mol% BaGeO3, the calcined powders (1150 °C) as well as the once-sintered samples consist of BaSnO3 and orthorhombic BaGeO3 at room temperature. A gradual appearance of hexagonal BaGeO3 can be observed in calcined powders and once-sintered ceramics with a BaGeO3 content above 50 mol%. After sintering at ≥1200 °C for more than 1 h all ceramic bodies consist of BaSnO3 and orthorhombic BaGeO3. The addition of BaGeO3 leads to a considerable reduction of the sintering temperature and to a strong densification. Sintering at 1180 °C for 10 h and an addition of only 1 mol% BaGeO3 leads to dense ceramic bodies with cubic-like grains.