Structural Interpretation of Sintering Temperature Effect on Optical and Electrical Properties of Pr3+‐Substituted Nickel Ferrites

Abstract

Herein, the sintering temperature effect on various properties of Pr3+‐substituted nickel ferrites prepared through the sol–gel–citrate autocombustion method is presented. The Rietveld refinement of X‐ray diffraction patterns confirms the formation of the inverse spinel nickel ferrite phase with an additional orthorhombic phase PrFeO3. The crystallinity of those samples is better with a lesser weight percentage of the secondary phase for higher sintered samples. Structural parameters like crystallite size, lattice parameter, microstrain, and bond lengths depend strongly on sintering temperature with an increasing trend. Scanning electron micrographs clearly show the grain growth of the samples with sintering temperature with the formation of a secondary phase at the grain boundaries. The photoluminescence study points to the photocatalytic nature of the compositions. The bandgaps of the samples are calculated using a UV–vis study, which shows an initial decrease in values with increasing sintering temperature. The electrical study confirms the grain and grain boundary contribution to the total conductivity. With higher sintering temperatures, activation energies decrease, but the dielectric loss and saturation dielectric constant tend to increase. The scaling of conductivity and dielectric loss spectra confirm the time–temperature superposition principle.