Precursor combustion synthesis of nanocrystalline cobalt substituted nickel zinc ferrites from hydrazinated mixed metal fumarates

• Convenient synthesis of hydrazinated mixed metal fumarates under nitrogen atmosphere.
• Six hydrazine molecules in precursor provide high exothermicity for the decomposition.
• Autocatalytic decomposition of precursors helps in ferritization at 410 °C.
• Single domain-superparamagnetic particles of uniform size in the range of 15–30 nm.

In present investigation, a systematic approach towards synthesis of nanocrystalline ferrites, CoxNi0.6−xZn0.4Fe2O4 (x = 0.1 and 0.4) has been reported by room temperature decomposition of precursors, CoxNi0.6−xZn0.4Fe2 (C4H2O4)3·6N2H4 (x = 0.1 and 0.4). The precursor complexes were characterized by Fourier transform infrared spectroscopy (FTIR), chemical analysis and thermal studies like isothermal mass loss, total mass loss, thermogravimetry (TG), derivative of thermogravimetry (DTG) and differential thermal analysis (DTA). The TG–DTG–DTA patterns of both precursors reveal multistep decomposition with complete ferritization at 410 °C. The thermally decomposed products were characterized by X-ray diffractometry (XRD) for phase purity. The FT-IR spectroscopy studies of the same shows complete removal of all organic moieties from decomposed precursors. The nanophasic nature of synthesized ferrites was confirmed by transmission electron microscopy (TEM) analysis as well as from broadening of XRD peaks. The AC magnetization studies show the existence of single domain and superparamagnetic particles, which supports nanosize particles distribution in the ferrite system under study.