Raman scattering study of polycrystalline magnetoelectric BiFeO3

The present work reports the preparation and room temperature Raman study of polycrystalline magnetoelectric BiFeO3 (BFO) material. All the 13 Raman modes predicted by group theory (GammaRaman,R3c=4A1+9E) for R3c structure of BFO are observed in the present work. To distinguish A1 and E modes, Raman measurements have been carried out in parallel and crossed polarization configurations. In addition to other modes, intense sharp peaks corresponding to A1-1, A1-2, and A1-3 modes at 135.15+/-1.38, 167.08+/-0.34 and 218.11+/-0.45cm-1, respectively, are clearly observed in the polycrystalline BFO sample. The results of Raman spectra matches well with the recently reported single crystal and epitaxially grown thin film of BFO. Further, X-ray diffraction (XRD), differential scanning calorimetry (DSC), Mossbauer spectroscopy, vibrating sample magnetometer are used to characterize the sample. The XRD result shows BFO as a major phase along with about 1% impurity phase. Mossbauer spectrum show sextet at room temperature indicating the magnetic ordering. The observed isomer shift indicates the presence of Fe in trivalent oxidation state. DSC is used to find the Neel temperature (TN). The observed hyperfine parameters and TN match well with the literature. The room temperature magnetization measurement indicates the anti-ferromagnetic nature of the BFO sample.