High-Temperature Dielectric Response of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3: Does Burns Temperature Exist in Ferroelectric Relaxors?

TL;DR

This study investigates the dielectric response of relaxor ferroelectrics at high temperatures, challenging the existence of a specific Burns temperature and suggesting polar nanoregions form over a broad temperature range, with critical behavior similar to spin glasses.

Contribution

It provides evidence that polar nanoregions in relaxors form at temperatures higher than previously thought, and questions the existence of a distinct Burns temperature.

Findings

Dielectric dispersion at 600 K is due to surface-layer effects.

Polar nanoregions exist at temperatures up to 800 K.

Critical exponents suggest spin glass universality class.

Abstract

It has been considered that polar nanoregions in relaxors form at Burns temperature Td approx 600 K. High-temperature dielectric investigations of Pb(Mg1/3Nb2/3)O3 (PMN) and 0.7PMN-0.3PbTiO3 reveal, however, that the dielectric dispersion around 600 K appears due to the surface-layer contributions. The intrinsic response, analyzed in terms of the universal scaling, imply much higher Td or formation of polar nanoregions in a broad temperature range, while high dielectric constants manifest that polar order exists already at the highest measured temperatures of 800 K. The obtained critical exponents indicate critical behavior associated with universality classes typically found in spin glasses.