Insight into effects of Mn substitution in CoFe2O4 nano ferrites involving high frequency storage device application

Nanoferrites of the CoMnxFe(2-x)O4 series (x = 0.00, 0.05, 0.10, 0.15, 0.20) were synthesized using the sol-gel auto-combustion approach. Lattice constants were computed within the range of 8.312–8.406 Å, while crystallite sizes were estimated to be 55.20–31.40 nm using the Scherrer method. The different functional groups were found to correlate with different absorption bands using Fourier transform infrared (FTIR) spectroscopy. Five active modes were identified by Raman spectroscopy, revealing vibration modes of O2- ions at both tetrahedral and octahedral locations. The ferromagnetic hysteresis loop was observed in all the synthesized samples, and these are explained by Neel’s model. The ac conductivity decreases with increasing Mn2+ content at the Fe2+ site. Besides, both the dielectric constant and dielectric loss increased with increasing frequency. Moreover, the saturation magnetization (Ms), remnant magnetization (Mr), and coercivity (Hc) all showed declining trends with the increase in Mn2+ doping. The CoMn0.20Fe1.8O4 samples showed Ms ranging from 73.12 to 66.84 emu/g, Mr from 37.77 to 51.89 emu/g, and Hc from 1939 Oe to 1312 Oe after that coercivity increases, which makes it a promising candidate for the magnetic applications.