Effect of mediator on the auto combustion synthesis, magnetic properties, and electron density distribution of spinel ferrite Mn_0.05Zn_0.95Fe₂O₄

Single-phase spinel Mn_0.05Zn_0.95Fe₂O₄ was synthesised by auto combustion method using metal nitrates and Glycine via various mediators (a) Aloe vera, (b) ethylene glycol, and (c) egg white represented as (a) MZF-AV, (b) MZF-EG, and (c) MZF-EW respectively. The experimental characterisation was done using XRD, vibration sample magnetometer (VSM), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and UV–Visible spectrometer. The structural parameters and electron density distribution, hence bonding, were analysed using the computational techniques of Rietveld and the maximum entropy method (MEM). The estimated minimum crystallite size of the sample by x-ray method is 16 ± 0.72 nm for the sample grown via the Aloe vera. VSM results show superparamagnetism in MZF-AV was further confirmed by magnetization vs temperature with zero field cooled (ZFC)/field cooled (FC) protocol. The ZFC/FC curve reveals the blocking temperature of 57.7 K and single domain superparamagnetic particle size of 9.4 nm for the sample MZF-AV. The samples MZF-EG and MZF-EW show little ferromagnetism with small coercivity and retentivity. SEM results show hexagonal-shaped crystal formation for the sample grown via egg white, while others show non-spherical highly agglomerated particles. EDX results are convincing without any impurity addition. MEM electron density analysis favours superparamagnetism with maximum tetrahedral A–O and octahedral B–O covalent bonding. Electron density distribution analysis based on MEM shows a significant variation in type and strength of inter bonding between A–O, B–O, and super exchange bonding between A–A, A–B, and B–B. (author)