Mg2SnO4 ceramics I. Synthesis–processing–microstructure correlation

Phase stability of magnesium meta- and orthostannate has been examined in samples synthesized via the traditional solid-state reaction (SSR) and a novel self-heat-sustained (SHS) technique with two molar ratios of magnesium to tin (viz., 1:1 and 2:1). The powder mixtures were calcined over a wide temperature–time (T–t) span ranging from 600 to 1300°C and 3 to 72 h. The powders obtained from the two preparative methods have been processed and sintered under identical conditions. In the 2:1 molar mixtures, Mg2SnO4 has been formed as a single phase up on calcination in both SRR and SHS methods. This phase remained the only compound in the sintered bodies as well. In the 1:1 composition, the ultimate reaction product was a mixture of Mg2SnO4 and SnO2. Both SSR and SHS techniques with 2:1 molar mixture yielded a single phase Mg2SnO4 in the sintered compacts. Compacts with near zero porosity could be achieved in SSR derived samples up on sintering up to 1600°C, while some significant porosity was an interesting feature of the SHS derived samples. Systematic microstructural evolution with the variation of sintering conditions has been discussed.