Mossbauer studies of manganese ferrite fine particles processed by ball-milling

Structural and magnetic evolutions in manganese ferrite caused by high-energy ball-milling are investigated by X-ray diffraction, magnetization and Mossbauer spectroscopy. The average particle size was reduced appreciably after a relatively short period of milling. Mossbauer studies at room temperature and at 10 K in an external magnetic field of 5T are used to investigate hyperfine interaction, cation distributions, and magnetic structure before and after milling. An increase in the inversion parameter is observed with increasing the milling time, which is attributed to the reduction of particle size. As a result of spin canting rearrangement, the saturation magnetization decreases with decreasing average particle size. This canting appears to be associated with a surface layer, where the spins are inclined to the direction of the net magnetic moment. (C) 2000 Elsevier Science B.V. All rights reserved.