Nature of ferroelectric to paraelectric phase transition in multiferroic 0.8BiFeO3-0.2Pb(Fe1/2Nb1/2)O3 ceramics

We present here the results of high temperature powder x-ray diffraction study on 0.8BiFeO(3)-0.2Pb(Fe1/2Nb1/2)O-3, which is isostructural with the well known multiferroic BiFeO3 (BF). It is shown that the room temperature ferroelectric phase of 0.8BF-0.2PFN in the R3c space group transforms to the paraelectric/paraelastic cubic (Pm (3) over barm) phase directly without any intermediate beta phase reported in the literature for pure BF. This transition is of first order type as confirmed by the coexistence of R3c and Pm (3) over barm phases over a 100 K range and discontinuous change in the unit cell volume. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3428410]