Effect of annealing temperature on structure, magnetic and optical properties of copper ferrite (CuFe2O4) nanoparticles synthesized by sol-gel auto-combustion technique

Abstract

The sol-gel-auto-combustion procedure had been widely used technique for analyzing structural, morphological, magnetic  and optical properties of copper ferrite (CuFe₂O₄) nanoparticles (copper nano ferrite), which exhibit to annealed for four hours in the air at 200, 400, 600, 800 and 1000°C. XRD analysis revealed, structural phase transformation of copper nano ferrite to tetragonal from cubic phase with an increase in the c/a ratio and in the form of elevating annealed temperature and which was assigned to tetragonal distortion by JTE (Jahn-Teller Effect) of copper ions. FTIR study revealed that, the existence of two band positions in the range of 585.7 and 413.7 cm^-1 indicating the formation of spinel ferrite structure. FESEM image was confirmed with EDAX techniques, random morphology with a large cluster of particles and the presence of pure copper ferrite nanoparticles were observed. The VSM study showed that, the variation in the magnetic saturation and coercivity were observed due to change in phase transition and grain size. The highest saturation magnet (M_s) (28.39 emu/g) was observed in copper nano ferrite and recovered at 1000°C. In contrast, the lowest value (13.23 emu/g) was found at 600°C. Coercivity (H_c) increased with increase annealing temperatures and its maximum value (1638 Oe) was found at 800°C. The band gap energy (E_g) of copper nano ferrite decreased from 2.12 to 1.56 eV by UV-VIS analysis with increased annealing temperature due to the increased crystalline size.