Effect of fuel-to-oxidizer ratio on the structural and magnetic properties of Zn$_{0.5}$Mn$_{0.5}$Fe$_2$O$_4$ nanoferrites synthesized via glycine-nitrate combustion
Abstract:
Nanostructured Zn$_{0.5}$Mn$_{0.5}$Fe$_2$O$_4$ ferrites were synthesized by the glycine–nitrate solution combustion method with the fuel-to-oxidizer ratio $f$ varied from 0.4 to 1.6 in order to clarify the influence of redox conditions on structure and magnetic properties. X-ray diffraction confirms the formation of single-phase cubic spinel for all compositions, with the crystallite size changing from $\sim$8 to 108 nm and the minimum values of both crystallite size and lattice parameter (8.420$\mathring{\mathrm{A}}$) obtained under fuel-deficient conditions ($f$ = 0.4); the lattice microstrain does not exceed 0.5%. SEM observations reveal 3 – 5 $\mu$m agglomerates composed of 30 – 190 nm particles, while EDX analysis shows cation ratios close to the nominal composition. Magnetic measurements at 300 K demonstrate typical soft-magnetic behavior with saturation magnetization ranging from 16.1 to 68.3 emu/g, residual magnetization from 1.8 to 20.3 emu/g and coercive force from 34.7 to 85.6 Oe, all efficiently tuned by the fuel content. The highest saturation magnetization is achieved near the stoichiometric regime ($f\approx$ 0.8 – 1.0), whereas fuel-rich mixtures result in increased coercivity due to microstructural refinement and lattice strain. The established correlations between combustion conditions, structural parameters and magnetic response show that controlled variation of the fuel ratio is an effective tool for tailoring Zn–Mn ferrite nanopowders for low-loss soft-magnetic applications.
Keywords:Zn–Mn ferrites, solution combustion, fuel-to-oxidizer ration, crystal structure, microstructure, magnetic properties, soft magnetic materials.
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