Published online by Cambridge University Press: 01 June 2006
Powders of Ba0.65Sr0.35TiO3 have been prepared by solution-based and conventional mixed-oxide routes. Powders made by freeze-drying a precursor solution of mixed catecholate complexes of BaTiO3 and SrTiO3 had the smallest particle size, but secondary grain growth during sintering negated the anticipated benefits of the nano-sized powder in relation to ceramic densification and microstructural control. Addition of manganese oxide suppressed secondary grain growth for catecholate powders, allowing 97% dense ceramics to be produced at a sintering temperature of 1300 °C, with grain sizes of ≤5 μm. Doped mixed-oxide samples continued to show secondary grain growth, leading to coarse microstructures with grain sizes ≤100 μm after sintering at 1400 °C. Curie peaks for catecholate samples were sharper than those for mixed-oxide samples, suggesting a more uniform distribution of Ba and Sr ions in the powders. Difficulties were encountered in controlling the (Ba + Sr)/Ti ratio of powders made by an oxalate solution-precipitation route.