The effect of temperature on the structure and magnetic properties of Co0.5Ni0.5Fe2O4 spinel nanoferrite

• Co0.5Ni0.5Fe2O4 nanoparticle ferrite was produced via a glycol-thermal.
• XRD,EDX, SEM, TEM, FTIR, CFM-VSM techniques were applied to the study.
• The results indicate a soft and hard magnetic behavior of the sample.
• Coercivity and magnetization follow the Kneller's and Bloch's laws.
• Sample transformed from single- to multi-domain magnetic structure.

Nanocrystalline Co0.5Ni05Fe2O4 ferrite with average crystallite size of 7.6 nm and lattice constant of 0.8372 nm was synthesized via a glycol-thermal process. The structure parameters and morphology of the as-synthesized sample and annealed samples were characterized by XRD, EDX, FTIR, HRSEM and HRTEM. The hyperfine interactions, iron distribution on the tetrahedral and octahedral sites for the as-synthesized sample and samples annealed at 500 °C were deduced by Mössbauer spectroscopy measurements at 300 K. The magnetization measurements for the as-synthesized and annealed samples (300–900 °C) were obtained by a vibrating sample magnetometer on a cryogen free measurement system at different isothermal temperatures (4–300 K) in external applied magnetic fields of ±5 T. The temperature dependence of the magnetic properties such as coercive field, saturation magnetization, remanent magnetization and squareness of hysteresis loops were investigated. The sample transformed from single-domain to multi-domain configuration at particle size of about 31 nm. At 300 K, the sample annealed at 700 °C exhibits a maximum coercivity. The as-prepared sample shows a substantial increase in coercivity from 0.182 kOe at 300 K to 6.018 kOe at 4 K.