Macroscopic polarization in the nominally ergodic relaxor state of lead magnesium niobate

TL;DR

This study investigates the persistent macroscopic polarization in lead magnesium niobate's relaxor phase, revealing that polar nano entities influence its dynamic response and challenging the notion of an ergodic state below Burns temperature.

Contribution

It provides new evidence linking polar nano entities to macroscopic polarization and questions the ergodic nature of PMN below Burns temperature.

Findings

Persistent macroscopic polarity observed in PMN.

Polar nano entities are responsible for dynamic nonlinear dielectric behavior.

Ergodic state may not exist in PMN below Burns temperature.

Abstract

Macroscopic polarity and its dynamic response to external electric fields and temperature in the nominally ergodic relaxor phase of pristine lead magnesium niobate crystals and ceramics, Pb(Mg1/3Nb2/3)O3 (PMN), were investigated. Dynamic pyroelectric measurements provide evidence for persistent macroscopic polarity of the samples. Annealing experiments below and above Burns temperature of polarized samples relate this polarity to the presence of polar nano entities and their dynamics. The dc electric field strength required for macroscopic polarization reversal is similar to the amplitude of the ac field where dynamic nonlinear dielectric permittivity reaches maximum. Consequently, the aforementioned maximum is related to the reorientation of polar nano entities. The results question the existence of an ergodic state in PMN below Burns temperature.