The PZT system (PbTixZr1−xO3, 0≤x≤1.0): High temperature X-ray diffraction studies. Complete x-T phase diagram of real solid solutions (Part 3)

Based on high temperature x-ray diffraction studies of the PZT system (PbTixZr1−xO3, 0.0≤x≤1.0) the complete x-T phase diagram of solid solutions is built, which exhibits peculiar properties due to the real structure of ceramics: - irregularity of the phase transition line to the paraelectric state, which is more pronounced in the rhombohedral–tetragonal transition region; - appearance of intermediate “region of indistinct symmetry” at 0.2≤x≤1.0, which forestalls the transition to the non-polar cubic phase at temperature increase; - formation of two morphotropic regions: contracting (rhombic–rhombohedral) and expanding (rhombohedral–tetragonal) at temperature increase; - richness of single-symmetry phase diagram fragments by regions of coexistence of phase states. The homogeneity regions of the real solid solutions contain phase-boundary lines of a new type evidencing of intraphase transitions prevailing in the rhombohedral phase, which show up in the presence of two and more different cell values (preserving the global crystal lattice symmetry).