The energetics of the (1 - x)PMN-xPT solid solutions have been investigated using high temperature oxide melt solution calorimetry in 3Na 2O·4MoO3 solvent at 702 °C. The solid solutions show positive heats of mixing, reflecting the changes in structure from cubic to tetragonal to monoclinic and the morphotropic phase transition. The synthesis of a perovskite phase without a secondary pyrochlore phase depends on the annealing temperature and time. The enthalpies of reactions involved in synthesis and decomposition of the PMN perovskite were measured for the first time by oxide melt solution calorimetry. The decomposition of perovskite to pyrochlore plus MgO and PbO is energetically favorable, as is the formation of perovskite from columbite and lead oxide.
ASJC Scopus subject areas
- Materials Chemistry