Magnetic interactions in high-energy ball-milled NiZnFe2O4/SiO2 composites

• Published in: Physica. B, Condensed matter Vol. 398; no. 2; pp. 241 - 244
• Main Authors: POZO LOPEZ, G, SILVETTI, S. P, URRETA, S. E, CABANILLAS, E. D
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.09.2007
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diamagnetism, paramagnetism and superparamagnetism; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Magnetic properties and materials; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Physics; Nickel oxides; NiZn ferrite/SiO2 composites; Mechanical alloying; Hysteresis; Ball mill; Isothermal annealing; Magnetic hysteresis; 75.50.Kj; Superparamagnetism; Magnetic transitions; Heat treatments; Oxidizing atmosphere; Ferrites; Zinc oxides; Composite materials; Fine particle; Silicon oxides; Iron oxides; Microstructure; Exchange interactions
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2007.04.024

Composites Ni0.5Zn0.5Fe2O4/SiO2 are obtained after high-energy ball milling precursor oxides, in stoichiometric proportions, for 200h at room temperature and further isothermal annealing for 1h at 1273K, under air and argon atmosphere, respectively. After 200h grinding, a complex microstructure develops with small hematite crystals mixed with SiO2 and remanent NiO and ZnO particles, and very small NiZn ferrite clusters, reaching a mean size of . The high temperature treatments remove the hematite grains from the powder and promote the growth of NiZn ferrite grains to reach mean sizes nearly . For treatments in oxidizing atmospheres, the major phases are SiO2 and NiZn ferrite, while for annealing in Ar a new phase appears, fayalite, which is paramagnetic at room temperature. The M-H loops are all well described by the sum of a ferromagnetic and a superparamagnetic-like contribution. The observed properties are interpreted considering the different magnetic phases obtained, their crystal sizes and their mutual interactions.