Microstructural evolution in MSnO3 ceramics derived via self-heat-sustained (SHS) reaction technique

A thorough study of MSnO3 (M = Ca, Sr and Ba) compounds with respect to their synthesis, processing and microstructural characterization has been made. In order to establish a standard methodology with identical and beneficial microstructure and reproducible electrical characteristics, a novel preparative method called self-heat-sustained (SHS) reaction technique was employed. Evolution of microstructure which is intimately related to the envisaged properties in the ceramics, was closely and systematically followed in terms of wide temperature-soak time (T-t) profiles. The results showed that while a well-densified microstructure with small grain size (similar to 1 mu m) and near zero porosity could be obtained by selecting a sintering schedule of 1350 degrees C/x h (48 h < x less than or equal to 60 h) for CaSnO3 samples, very well sintered samples with relatively larger grains (3-5 mu m) and minimal porosity could also be obtained by sintering at 1600 degrees C for 2 h. Well-densified microstructure with small grain size and zero or near zero porosity could be obtained by a sintering schedule of 1350 degrees C/x h (12 h < x less than or equal to 24 h) in SrSnO3 samples. Sintering of BaSnO3 proved to be the most difficult. The BaSnO3 samples could only be densified to the desired level by soaking the powder compacts for 2 h at 1600 degrees C. The "sugar cube" features were replaced by the spherical grains (average size 1-2 mu m). (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.