Problems in crystal chemistry of ferroelectric and antiferroelectric perovskites PbB0.5′B0.5″O3

The most interesting problems in the crystal chemistry of ferroelectric and antiferroelectric perovskites PbB0.5′B0.5″O3 are considered. The properties and specific features of perovskites (such as the smearing of ferroelectric phase transitions, relaxor state, ferroelectric-antiferroelectric transformations, and spontaneous phase transitions to a macrodomain state) depend on the distribution of B′ and B″ ions over octahedral positions of the crystal lattice, i.e., on the order and disorder of these ions.