Effect of heating temperature on structural, magnetic, and dielectric properties of Magnesium ferrites prepared in the presence of Solanum Lycopersicum fruit extract

摘要

MgFe_2O_4 ferrite was synthesized in the presence of Solanum Lycopersicum fruit extract using sol-gel auto-combustion technique and heated from 650 °C to 1050 °C with the difference of 100 °C. The effect of heating temperature on phase purity, crystal structure, and magnetic as well as dielectric properties was systematically investigated. XRD analysis show that all samples consist of a single phase cubic spinel structure. The average crystallite size of heated samples varied from 10 to 26 nm, it was observed that crystallite size increases with the calcination temperature and average grain size was found in between 18 and 65 nm. SEM micrographs show that there is a drastic reduction in the grain size in the sample prepared in presence of tomato extract (65 nm) compared to the sample prepared without tomato extract (373 nm) and heated at 1050 °C for 4 h. All samples belong to soft ferrite (H_C ~ 10 to 70 Oe) and possess a multi-domain structure. As heating temperature increases the values of both saturation magnetization (M_s) and hyperfine magnetic field (H_(hf)) are found to increase. The frequency-dependent dielectric phenomenon was observed in all prepared samples and single one-fourth semi-circles observed in Nyquist plot because of the contribution of the grain boundaries over the grain conductions. M" and Z" vs frequency plots reveal the absence of Debye relaxation in prepared compositions.