THE EFFECT OF NEAREST NEIGHBOR [Pb─O] DIVACANCY PAIRS ON THE FERROELECTRIC-RELAXOR TRANSITION IN NANO-ORDERED Pb(Sc_1/2Nb_1/2)O₃

ABSTRACT

Molecular dynamics simulations were performed on a first-principles-based effective Hamiltonians for chemically short-range ordered Pb(Sc_1/2Nb_1/2) O₃ with nearest neighbor [Pb─O] divacancy pairs. The divacancy-concentration (X_[Pb-O]) vs. temperature phase diagram was calculated, and it is topologically equivalent to the hydrostatic pressure (P) vs. temperature diagram: a ferroelectric ground-state phase at low X_{[Pb - O]} (P); that transforms to a relaxor paraelectric phase at moderate X_{[Pb - O]} (P); followed by a crossover to a normal paraelectric phase at high X_{[Pb - O]}(P).

Keywords:

• PSN
• relaxor ferroelectric
• lead vacancies
• oxygen vacancies
• phase transitions
• random fields