A MOSSBAUER-EFFECT STUDY OF BARIUM FERRITE BALL-MILLED IN AIR

The effects of dry-milling BaFe12O19 in air for periods of 190, 360, 590, 690 and 1000 h have been investigated by X-ray diffraction and Mossbauer effect measurements. The sizes of the BaFe12O19 particles decrease on milling, as expected, although a partial decomposition of BaFe12O19 to alpha-Fe2O3 is found to rake place on extended milling (1000 h). The room temperature Mossbauer spectra are consistent with superparamagnetic relaxation associated with the fine BaFe12O19 and alpha-Fe2O3 particles. The X-ray diffraction patterns of all the milled samples exhibit features indicative of a disordered structural state, consistent with the nanoscale particles and a nanostructured state.