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 the ir synthesis, processing and microstructural characterization has been made . In order to establish a standard methodology with identical and beneficia l microstructure and reproducible electrical characteristics, a novel prepa rative method called self-heat-sustained (SHS) reaction technique was emplo yed. Evolution of microstructure which is intimately related to the envisag ed properties in the ceramics, was closely and systematically followed in t erms of wide temperature-soak time (T-t) profiles. The results showed that while a well-densified microstructure with small grain size (similar to 1 m u m) and near zero porosity could be obtained by selecting a sintering sche dule 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 degre es 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 b e 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 gr ains (average size 1-2 mu m). (C) 2000 Elsevier Science Ltd and Techna S.r. l. All rights reserved.