Nickel−Zinc Ferrite from Reverse Micelle Process: Structural and Magnetic Properties, Mössbauer Spectroscopy Characterization

Abstract

Nickel−zinc ferrite (Ni0.58Zn0.42Fe2O4) nanoparticles with an average crystallite size of about 8.4 nm were synthesized by reverse micelle technique. Bulk sample was prepared by annealing nickel−zinc ferrite (NZFO) nanoparticles at 1473 K. Room temperature Mossbauer spectra of NZFO nanoparticles exhibit collective magnetic excitations, while annealed (bulk) NZFO particles have the ferrimagnetic phase. At 5 K, the broad shape of Mossbauer spectral lines for nanoparticles in comparison to bulk particles provide clear evidence of a wide distribution of magnetic fields acting at the Fe3+ nuclei in the nanoparticles. Bulk NZFO particles and inner core of nanoparticles exhibit a fully inverse spinel structure with a Neel type collinear spin arrangement, whereas the major feature of the ionic and spin configuration in the grain boundary (surface) region are a nonequilibrium cation distribution and a canted spin arrangement. The cation distribution of nano and bulk particles has been studied by using in-field Mos...