Problems in crystal chemistry of ferroelectric and antiferroelectric perovskites PbB

The most interesting problems in the crystal chemistry of ferroelectric and antiferroelectric perovskites PbB _0.5 ^′ B _0.5 ^″ 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. __________ Translated from Kristallografiya, Vol. 49, No. 5, 2004, pp. 806–810. Original Russian Text Copyright ? 2004 by Isupov.