Synthesis of SrxBa(1-x)TiO3 Solid Solutions from the Mechanically Activated System BaCO3 - SrCO3 - TiO2

Mixtures xSrCO 3 (1 - x)BaCO 3 TiO 2 (0 < x < 1) have been mechanically activated by high energy milling in order to promote the formation of mixed (Sr,Ba) carbonate that decomposes, in a single stage, at temperatures generally lower than for the corresponding physical mixtures. By annealing such milled mixtures at high temperatures (≈ 1000 °C), cubic solid solutions Sr x Ba (1-x) TiO 3 are obtained (except at x = 0.1 where a tetragonal solid solution forms) whose lattice parameters decrease linearly with x. The enthalpy of solid solution formation changes with composition showing higher values in the x range between x = 0.2 and 0.5 where the reaction has been demonstrated to occur via the formation of Ba 2 TiO 4 . By contrast, the enthalpy values decrease for x > 0.5.