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Unexpected Ground State Structures in Relaxor Ferroelectrics
Published
Author(s)
Benjamin P. Burton, Eric J. Cockayne
Abstract
Cluster expansion Hamiltonians derived from pseudopotential total energies were used to predict ground-state (GS) cation configurations for some A(B^{3+}1⁄2B'^{5+}1⁄2)O3, A(B^{2+}{1/3}B'^{5+}{2/3})O3 , and [A^{1+}1⁄2A'^{3+}1⁄2]BO3 perovskites. Predicted GS structures for Pb(Mg1/3 Nb2/3)O3 (PMN), Pb(Mg1/3Ta2/3)O3, [Na1/2Bi1/2 ]TiO3 , and [K1/2 Bi1/2]TiO3 differ from those predicted by a purely ionic model. Monte Carlo simulation of cation order-disorder phenomena in PMN predicts the transition sequence: [001]NCC' 1:1 Disordered.