Temperature-dependent Raman scattering studies of polycrystalline BiFeO3 bulk ceramics

Abstract

This work reports the temperature-dependent Raman scattering study of mutiferroic BiFeO3 (BFO) bulk ceramics in a wide temperature range of 93-843 K. The polycrystalline samples are sintered at four different temperatures and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry, differential scanning calorimetry (DSC), and optical microscopy. The microstructure shows remarkable changes in terms of grain size and domain pattern as the sintering temperature increases. The DSC curves show prominent exothermic peaks at 645 K, the antiferromagnetic-paramagnetic phase transition temperature. The Raman spectra of all the four specimens reveal strong anomalies in the vicinity of the Neel temperature, which can be attributed to the multiferroic nature of BFO. The Raman scattering studies also reveal considerable spectral changes at a temperature range of 140-200 K in all the specimens, which can be inferred to a further spin-reorientation transition exhibited in BFO at a cryogenic temperature. Copyright (C) 2008 John Wiley & Sons, Ltd.