Study on preparation of nanocrystalline ferrites using spent alkaline Zn–Mn batteries

The nanocrystalline ferrites were synthesized by sol–gel and self-propagating combustion methods using spent alkaline Zn–Mn batteries dissolved in nitric acid. The thermal decomposition process of dried gels, the essence of auto-combustion and the morphological structure of nanocrystalline ferrites were investigated by using DTA, TG, IR, XRD and SEM. The precise metal ion stoichiometry of the nanocrystalline ferrites was analyzed by ICP. The results demonstrated that the essence of auto-combustion of the dried gels was oxidation–reduction reaction induced by heat and the nanocrystalline Mn–Zn ferrites with a diameter of 20 nm could be prepared directly by auto-combustion reaction.