The Effect of Milling time on Phase Formation and Curie Temperature of Ultrafine Mn-ferrite

Nano sized MnFe2O4 powders were prepared via mechanochemical processing (MCP), using a refined domestic iron oxide (hematite) and manganese oxide as starting materials. Milling was performed in a SPEX 8000D mixer/mill unit at different milling times in air, Argon and oxygen atmospheres. In order to obtain a single-phase sample, the as-milled powders were annealed at different temperatures and in different atmospheres. Phase character of the as-milled and annealed powders was studied by a Bruker diffractometer, D8 model. Particle size of the powders was calculated, using Scherrer’s formula. Saturation magnetization of the samples was measured, using a sensitive permeameter. Also curie temperature of samples was measured with a punctual LCR meter .The results show that milling in Argon and annealing in vacuum leads to a single-phase powder at lower annealing temperature in comparison with those annealed in conventional ceramic technique.