High temperature ferroic phase transitions and evidence of paraelectric cubic phase in the multiferroic 0.8BiFeO_3-0.2BaTiO_3

摘要

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 β-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.