The Effect of Co-Doping on the Structural and Magnetic Properties of Single-Domain Crystalline Copper Ferrite Nanoparticles

Abstract

Nanoparticles of Co-doped copper ferrite, Cu0.75Co0.25Fe2O4, were successfully synthesized by hydrothermal method. The preparation conditions were optimized to produce small nanoparticles with crystallite size of 20 nm that fall into the single-domain regime. The influence of Co-doping on the structure and magnetic properties of pure copper ferrite, CuFe2O4, was investigated. The prepared ferrite nanoparticles were found to be in a single structural phase with a spinel-type structure, according to the XRD and FT-IR measurements. When compared to pure Cu ferrite, the addition of Co increased the lattice constant and decreased the density. The TEM results confirmed the spherical morphology of the prepared ferrite nanoparticles. For the entire temperature range of the ferrite nanoparticles, the magnetization measurements showed a single ferrimagnetic phase. It was observed that the coercivity and remanent magnetization increased with decreasing temperature. Magnetic anisotropy was found to increase with Co-doping in comparison to pure Cu ferrite. The ZFC–FC magnetization curves showed that the blocking temperature (TB) of the prepared nanoparticles is above room temperature, demonstrating that they are ferrimagnetic at room temperature and below. Additionally, it was found that decreasing the magnetic field lowers TB. The FC curves below TB were observed to be nearly flat, indicating spin-glass behavior that might be attributed to nanoparticle interactions and/or surface effects such as spin canting and spin disorder.

Keywords

• copper ferrite
• single-domain particle
• Rietveld refinement
• magnetization
• spin glass
• Kneller’s law