High temperature ferroic phase transitions and evidence of paraelectric cubic phase in the multiferroic 0.8BiFeO3-0.2BaTiO3

We present here results of a powder x-ray diffraction study on the multiferroic 0.8BiFeO(3)-0.2BaTiO(3) in the temperature range of 300-925 K. Our results provide unambiguous evidence for paraelectric cubic phase. We do not find any evidence for intermediate beta-phase in our studies. The rhombohedral to cubic phase transition is shown to be of first order as revealed by the coexistence of cubic and rhombohedral phases over 100 K range and a discontinuous change in the unit cell volume. An anomaly in the unit cell volume at the magnetic transition temperature indicative of the magnetoelastic coupling is also reported. (C) 2009 American Institute of Physics. [doi:10.1063/1.3242419]