Solution combustion approach to the phase pure nanocrystalline lithium ferrite (Li$_{0.5}$Fe$_{2.5}$O$_4$) with spinel structure and magnetically soft behavior

Lithium ferrite nanoparticles (Li$_{0.5}$Fe$_{2.5}$O$_4$) were synthesized via the solution combustion method with a substantial deficiency of organic fuel (glycine, $f$ = 0.05), followed by heat treatment of X-ray amorphous combustion products at temperatures ranging from 500 to 750$^\circ$C. Comprehensive characterization was performed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), atomic absorption spectrometry (AAS), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results indicate significant morphological and structural changes in the nanopowders depending on the heat treatment temperature. Average particle sizes ranged from 14.2 to 59.5 nm, while crystallinity varied from 89.4% to 62.8%. Magnetic properties also varied, with coercivity $(H_c)$ between 58.4 and 102.4 Oe, residual magnetization $(M_r)$ from 5.2 to 15.4 emu/g, and saturation magnetization $(M_s)$ from 35.1 to 60.7 emu/g. These findings demonstrate that pure lithium ferrite nanoparticles, free from impurity oxide phases, can be produced through controlled heat treatment of X-ray amorphous combustion products. Furthermore, the magnetic properties of the nanoparticles are highly sensitive to the specific heat treatment temperature, indicating that thermal processing conditions play a crucial role in determining their magnetic behavior.