Tetragonal and rhombohedral induced polar order fromthe relaxor state of PbZn1/3Nb2/3O3

Abstract

Structural and dielectric characterizations of the relaxor ferroelectric PbZn1/3Nb2/3O3(PZN) were carried out on single crystals in the temperature range ofthe dielectric anomaly (370 K < T < 440 K),under dc electric field applied along [001]-and [111]-directions. Twoferroelectric phases, tetragonal (T) and rhombohedral (R), can be fieldinduced in this temperature range, the symmetry of which depends onthe direction of the applied field, [001] and [111] respectively. E–Tdiagrams were built and interpreted under the consideration of polar nano-regions(PNRs) with a prominent tetragonal component. These PNRs prevent the onset of amonodomain state when the field is applied along [111] and explain the features ofPZN for an applied field along [001]: large lattice strain, easy onset of the T phaseand suppression of the dielectric relaxation for E ≥ 1.5 kV cm−1.The microscopic origin of these PNRs can be discussed in relation with recentnuclear magnetic resonance and structural results reported in other isomorphousrelaxors.