Improving the Properties of Ni0.4Cu0.4Cd0.2Fe2O4 Spinel Ferrites via Heat Treatment for Electrical and Optoelectronic Applications

This study examines the effects of varying calcination temperatures on the properties of Ni 0.4 Cu 0.4 Cd 0.2 Fe 2 O 4 spinel ferrites. As confirmed by X-ray diffraction measurements, the compound calcined at 950°C exhibits a larger average crystallite size and lattice constant than the sample calcined at 850°C. The electrical conductivity study demonstrated semiconductor behavior for both samples, following the non-overlapping small polaron tunneling (NSPT) model for conduction. The samples showed high electrical resistivity and decreased activation energy ( E a ) from 0.33 eV (at 850°C) to 0.31 eV (at 950°C), suggesting that they could be used in microwave absorption devices. The optical measurements reveal that the samples present direct optical transitions with an estimated optical bandgap energy ( E g ) of 2.61 eV at 850°C and 2.39 eV at 950°C. Analyzing the refractive index change provided the Cauchy parameters, while the Wemple–DiDomenico relationship provided the dispersion energy parameters. Other optical characteristics, like the extinction coefficient, penetration depth, dielectric constants, and optical conductivity, were also thoroughly examined. These optical characteristics offered insightful information about the synthesized samples' possible optoelectronic uses.