Effect of nearest neighbor Pb-O divacancy pairs on the ferroelectric-relaxor transition in Pb(Sc_½Nb_½)O₃

Abstract

Molecular dynamics simulations were performed on a first-principles-based effective Hamiltonian for Pb(Sc_½Nb_½)O₃ (PSN) with nearest neighbor Pb-O divacancy pairs. Simulations were performed for PSN with ideal chemical order, chemical short-range order, and random chemical disorder. Divacancy concentration vs temperature, X_[Pb-O] vs T, phase diagrams were calculated, and they are shown to be topologically equivalent to the previously calculated hydrostatic pressure vs temperature diagram. In PSN with ideal chemical order, the Burns temperature defines an isotherm, which is analogous to the "Griffiths phase" in the magnetic dilution problem.