Analyses of structure, electronic and multiferroic properties of Bi1-xNdxFeO3 (x = 0, 0.05, 0.10, 0.15, 0.20, 0.25) system

Abstract

Magnetoelectric multiferroics are of considerable interest due to the fascinating science and potential applications. In this study, multiferroic Bi1-xNdxFeO3 (0 ≤ x ≤ 0.25) samples have been prepared by a two-stage solid-state reaction method and correlation between various properties has been studied. It can be seen that Nd3+ substitution destabilized the polar R3c symmetry due to chemical strain effects arising from the size mismatch between Bi3+ and Nd3+ cations which triggered partial structural transformation to triclinic structure (P1symmetry). Raman scattering experiments elucidated slight changes in covalency of Bi–O bond and softening of modes corresponding to oxygen motion suggests a significant destabilization of FeO6 octahedra. The increase in magnetization has been attributed to the suppression of the spiral spin structure and variation in Fe–O–Fe bond angle due to the strain induced in the unit cell by Nd3+ substitution. The step-like feature in magnetization at the low field has been attributed to charge melting in connection with manganites. An anomalous decrease in coercivity with decrease in temperature has been observed for Bi0.75Nd0.25FeO3 sample which can be explained on the basis that the decrease in effective magnetic anisotropy and is an indicator of presence of magnetoelectric coupling. The bandgap increases with increase in Nd3+ content which is attributed to the decrease in interatomic lattice parameters which resulted in increased binding forces of valance electrons.