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 (∼1 μm) and near zero porosity could be obtained by selecting a sintering schedule of 1350°C/x h (48 h < x ⩽ 60 h) for CaSnO3 samples, very well sintered samples with relatively larger grains (3–5 μm) and minimal porosity could also be obtained by sintering at 1600°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°C/x h (12 h < x ⩽ 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°C. The “sugar cube” features were replaced by the spherical grains (average size 1–2 μm).