Giant piezoelectricity due to critical phenomena associated with restabilized rhombohedral phase in Pb(Mg1/3Nb2/3)O3–0.3PbTiO3

Abstract

Following our previous phenomenological modeling of pressure driven Curie transition and rhombohedral-tetragonal phase boundary in Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃, in this work we focus on combined effects of moderate pressure and [111]-oriented E-field and report huge broad peaks of piezoelectric d₃₃ in restabilized rhombohedral phase region stretching from around near-tricritical triple point (TP) to the regime of critical end point (CEP). TP and CEP exhibit distinctive features in the free energy landscape and pressure dependence of piezoelectric constants. We also find gigantic piezoelectricity in metastable monoclinic state coexisting with the restabilized rhombohedral state over the field level for the TP. Tricriticality occurred in a single ferroelectric composition on a phase plane of pressure vs. E-field is comparable to that observed in solid solutions on a phase plane of temperature vs. composition.