High P–T Raman study of transitions in relaxor multiferroic Pb(Fe0.5Nb0.5)O3

The vibrational and structural properties of Pb(Fe0.5Nb0.5)O3 have been investigated using Raman spectroscopy up to 40 GPa at 300 K and from 300 to 415 K at selected pressures. The measurements reveal three phase transitions, at 5.5, 8.7, and 24 GPa at room temperature. The temperature dependences of the spectra indicate transitions at 1.5 GPa, at 335 and 365 K. The results are consistent with the appearance of an intermediate tetragonal P4mm phase between the ferroelectric R3m and paraelectric Pm-3m phases. A P–T phase diagram is proposed that allows further insight into the magnetoelectric coupling present in this material. Copyright © 2015 John Wiley & Sons, Ltd.