Effect of Thermal Treatment at Inert Atmosphere on Structural and Magnetic Properties of Non-stoichiometric Zinc Ferrite Nanoparticles
Angelika Kmita, J. Żukrowski, Juliusz Kuciakowski, Marianna Marciszko‐Wiąckowska, Antoni Żywczak, Dorota Lachowicz, Marta Gajewska, Marcin Sikora
Abstract
Abstract Zinc ferrite nanoparticles were obtained by chemical methods (co-precipitation and thermal decomposition of metalorganic compounds) and systematically probed with volume (XRD, VSM), microscopic (TEM) and element sensitive probes (ICP-OES, Mössbauer Spectroscopy, XPS, XAFS). Magnetic studies proved the paramagnetic response of stoichiometric ZnFe 2 O 4 (ZF) nanoparticles, while superparamagnetic behavior was observed in as-synthesized, non-stoichiometric Zn x Fe 3− x O (NZF) nanoparticles. Upon annealing up to 1400 °C in an inert atmosphere, a significant change in the saturation magnetization of NZF nanoparticles was observed, which rose from approximately 50 up to 140 emu/g. We attribute this effect to the redistribution of cations in the spinel lattice and reduction of Fe 3+ to Fe 2+ during high-temperature treatment. Iron reduction is observed in both ZF and NZF nanoparticles, and it is related to the decomposition of zinc ferrite and associated sublimation of zinc oxide.