Phase formation and transitions in the lead magnesium niobate–lead titanate system

The phase formation and transition mechanism of lead magnesium niobate–lead titanate [(1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3, PMN-PT, 0≤x≤1] were investigated by thermal analysis and XRD. The effect of process parameters such as x values, synthesis temperatures, and excess PbO on phase transitions were studied in terms of the diffraction peak splitting. The results show that the perovskite phases undergo the transitions pseudocubic→rhombohedral→coexistence of rhombohedral and tetragonal→tetragonal in the x value range 0–1. At the composition of morphotropic phase boundary, preferential formation of the PMN-PT tetragonal phase was observed and discussed at elevated synthesis temperatures or with enhanced excess PbO.