Effect of Nd-substitution on structural and electrical properties of bismuth nano-ferrites

A series of neodymium-substituted bismuth ferrites with the chemical composition Bi_1-xNd_xFeO₃ (x = 0.0 to 0.05, with steps of 0.01) were prepared using the spontaneous combustion technique. The ferrites were characterized by structural and morphological investigations using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD results showed a shift in the diffraction peaks of bismuth ferrite with increasing Nd³⁺ content, a result consistent with the smaller radius of Nd³⁺ ions compared to Bi³⁺ ions. Increasing the neodymium content in the bismuth ferrite resulted in a significant decrease in the lattice parameters. The crystallite size was calculated using two methods: the Scherrer method and the Williamson-Hall (W–H) plot. Because Bi is a volatile material, abundant oxygen vacancies are expected in pure BiFeO3; these vacancies are inhibited by the Nd³⁺ double site. The electrical and dielectric properties of neodymium-substituted bismuth ferrite were studied, showing a pronounced increase in electrical conductivity with increasing temperature. In contrast, the dielectric constant and dielectric loss were limited to frequency effects, with the conduction mechanism and Maxwell-Wagner polarization being used to interpret the results. Neodium substitution in BiFeO₃ resulted in an increased saturation polarization (Ps), the appearance of an elliptical P-E ring, and an increased leakage current. It also significantly improved the photovoltaic properties of BiFeO₃ through the appearance of well-saturated rectangular P-E rings, which exhibit excellent photovoltaic behavior.