Synthesis and sintering of nano-sized BaSnO3 powders containing BaGeO3

The formation of solid solutions of the type [Ba(HOC₂H₄OH)₄][Sn_1−x Ge _x (OC₂H₄O)₃] as BaSn_1−x /Ge _x O₃ precursor and the phase evolution during its thermal decomposition are described in this paper. The 1,2-ethanediolato complexes can be decomposed to nano-sized BaSn_1−x /Ge _x O₃ preceramic powders. Samples with x = 0.05 consist of only a Ba(Sn,Ge)O₃ phase, whereas powders with x = 0.15 and 0.25 show diffraction patterns of both the Ba(Sn,Ge)O₃ and BaGeO₃ phase. The sintering behaviour was investigated on powders with a BaGeO₃ content of 5 and 15 mol%. These powders show a specific surface area of 15.4–15.9 m²/g and were obtained from calcination above 800 °C. The addition of BaGeO₃ reduced the sintering temperature of the ceramics drastically. BaSn_0.95Ge_0.05O₃ ceramics with a relative density of at least 90% can be obtained by sintering at 1150 °C for 1 h. The ceramic bodies reveal a fine microstructure with cubical-shaped grains between 0.25 and 0.6 μm. For dense ceramics, the sintering temperature could be reduced down to 1090 °C, when the soaking time was extended up to 10 h.