Crystal structure refinement of Bi1−xNdxFeO3 multiferroic by the Rietveld method

The effect of Nd doping on Bi1−xNdxFeO3 (x = 0.0, 0.175, 0.20) multiferroics synthesized by chemical co-precipitation method has been investigated by Rietveld analysis of X-ray powder diffraction (XRD) data. The formations of the single-phase compounds were confirmed by XRD. X-ray diffraction along with the Rietveld-refinement showed a gradual change in crystal structure from rhombohedral to triclinic with increasing Nd doping concentration. The bond distances along with bond angles between atoms for all the compounds were calculated which supports the structural results. Raman spectroscopy also recommends a structural change and is accompanied by the weakening of long-range ferroelectric order with increasing doping concentration (x). The results of Raman spectra for BiFeO3 (BFO) match well with the earlier reported bulk ceramic and epitaxially grown thin film of BFO. The ferroelectric-paraelectric transition in 20% Nd BFO substituted was explained according to the change of Bi–O covalent bond as a result of decline of stereochemical activity of Bi lone pair electron and is further confirmed through ferroelectric polarization (P–E) hysteresis loop.