Mixed spinel structure in nanocrystalline NiFe2O4 -: art. no. 184108

Nanocrystalline NiFe2O4 spinel has been synthesized with various grain sizes by high-energy ball milling. From the high-field magnetization studies and extended x-ray-absorption fine-structure, and Mossbauer measurements in an external magnetic field of 5 T applied parallel to the direction of gamma rays, we could observe that Ni2+ ions occupy tetrahedral sites on grain-size reduction due to milling. The Fe3+ spins have a canted structure and the canting angle increases with grain-size reduction. It is possible that the core Fe3+ spins are also canted because of the magnetocrystalline anisotropy introduced by the occupancy of the Ni2+ ions in the tetrahedral sites.