Room temperature dual ferroic behavior induced by (Bi, Ni) co-doping in nanocrystalline Nd0.7Bi0.3Fe1−xNixO3 (0 ≤ x ≤ 0.3)

Abstract

Nanocrystalline samples of Nd0.7Bi0.3Fe1−xNixO3 (x = 0, 0.1, 0.2, and 0.3) are synthesized using sol-gel auto-combustion process to investigate their structural, electrical, magnetic, and thermal properties. Phase purity and crystallinity of the samples are determined through x-ray diffraction (XRD) data. XRD patterns along with Rietveld refinement reveal orthorhombic structure with Pbnm space group. Unit cell parameters, bond angles, and bond lengths for all the samples have been determined. Crystallite size calculated by Scherrer equation is found to be in the range of 15–21 nm. The characteristic bands in the FTIR spectra further confirm the formation of our samples. FE-SEM images indicate the homogeneous distribution of particles on large scale and Ni-doped samples show some wall-like nanostructure in the morphology. EDX spectra confirm the elemental composition without any impurity element. The polarization versus electric field (P-E) and magnetization versus magnetic field (M-H) loops exhibit the multiferroic nature of the material. The sample with concentration x = 0.2 shows the maximum value of polarization (Pm) while maximum magnetization is achieved for x = 0.1 concentration. The specific heat capacity (Cp), endothermic, and exothermic peaks of the materials have been determined in the broad temperature range with the help of DTA measurements in the controlled nitrogen atmosphere. The Neel temperature of the parent system is found to be 742 K and that decreases up to 573 K on Ni doping.