Synthesis and sintering of nano-sized BaSnO_3 powders containing BaGeO_3

摘要

The formation of solid solutions of the type Ba(HOC_2H _4OH)_4Sn_(1-x) Ge _x (OC _2H_4O)_3 as BaSn_(1-x) /Ge _x O_3 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 O_3 preceramic powders. Samples with x = 0.05 consist of only a Ba(Sn,Ge)O_3 phase, whereas powders with x = 0.15 and 0.25 show diffraction patterns of both the Ba(Sn,Ge)O_3 and BaGeO_3 phase. The sintering behaviour was investigated on powders with a BaGeO_3 content of 5 and 15 mol. These powders show a specific surface area of 15.4-15.9 m~2/g and were obtained from calcination above 800 °C. The addition of BaGeO_3 reduced the sintering temperature of the ceramics drastically. BaSn _(0.95)Ge_(0.05)O_3 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.