Raman scattering spectra and ferroelectric properties of Bi 1-xNdxFeO3 (x= 0-0.2) multiferroic ceramics

Single-phase Bi1-xNdxFeO3(BNFOx) (x=0-0.2) multiferroic ceramics were prepared to study the effects of Nd substitution on their crystal structures, Raman scattering spectra, and ferroelectric properties. Rietveld refinement of x-ray diffraction data showed a gradual change in crystal structure from rhombohedral to pseudotetragonal via triclinic with increasing x. The evolvement of Raman normal modes with increasing x suggested that such structural change is accompanied by the weakening of long-range ferroelectric order. The simultaneous occurrence of abrupt mode evolvement and ferroelectric-paraelectric transition in BNFOx=0.175and BNFOx=0.2was explained according to the change of Bi-O covalent bonds as a result of the decline in the stereochemical activity of the Bi lone electron pair at 0.175≤x≤0.2.