Sol-Gel Auto-Combustion Synthesis of Magnetic Nanomaterials as an Efficient Route for Advanced Functional Materials

Thesol-gel auto-combustion method has emerged as a versatile and efficient technique for synthesizing magnetic nanomaterials with controlled structural and functional properties. This review comprehen sively examines the fundamental principles, reaction mechanisms, and process parameters governing the sol-gel auto-combustion synthesis of magnetic nanoparticles, with particular emphasis on ferrite materials. The method exploits the exothermic redox reaction between metal nitrates (oxidizers) and organic fuels such as citric acid, glycine, and urea to produce nanocrystalline powders at relatively low temperatures. Critical parameters including fuel-to-oxidizer ratio, pH, complexing agents, calcination temperature, and heating rate are systematically analyzed for their influence on phase purity, crystal lite size, morphology, and magnetic properties. The review covers the synthesis of various magnetic materials including spinel ferrites (MFe2O4, where M = Co, Ni, Zn, Mn), hexagonal ferrites (BaFe12O19, SrFe12O19), and mixed ferrite systems. Characterization techniques commonly employed for product evaluation, including X-ray diffraction, electron microscopy, and vibrating sample magnetometry, are discussed. Applications of sol-gel derived magnetic nanomaterials in data storage, biomedical fields, catalysis, environmental remediation, and electromagnetic interference shielding are highlighted. Finally, current challenges and future perspectives for advancing this synthesis methodology are outlined.