Correlation between particle size and magnetic characteristics of Mn-substituted ZnFe2O4 ferrites

• Mn-substituted Zn ferrites are synthesized at a lower sintering temperature of 800 °C, compared to that used in conventional techniques.
• Mostly, the spherical-shaped grains of uniform sizes, were distributed homogenously.
• Mn-substitution resulted in a gradual decrease in grain sizes.
• A strong correlation between grain sizes and magnetic characteristics have been observed.

We report synthesis of Zn1−xMnxFe2O4 (x = 0.0, 0.1, 0.3, 0.4 & 0.5) ferrites using sol-gel auto-combustion route while citric acid is used as a fuel. The study is aimed to explore the influence of Mn contents on structural parameters, morphological characteristics and magnetic properties of ZnFe2O4 ferrite samples while the impact of average grain dimensions on magnetic properties inferred from multi domain and single domain particle's effect is also analyzed. X-ray diffraction confirmed the configuration of single phase pure crystalline structure with low concentration of Mn while some impurity peaks were found for higher Mn contents. Lattice parameter was found to increase with increasing Mn contents while crystallite size was decreased. Average grain size was decreased from 240 to 150 nm with increasing Mn concentration which directly affected the magnetic properties. A decrease in saturation magnetization (from 52.35 to 45.80 emu/g) and an increase in coercivity (from 44 to 262 Oe) was observed with increasing Mn contents. A decrease in initial permeability and increase in hysteresis loss with increasing Mn contents was also evident. Coercive field and hysteresis losses were increased with decreasing average grain size while initial permeability was found to decrease with decrease in average grain size.