Abstract:
The effects of wet-milling barium ferrite in the presence of cationic or anionic surface active substances have been investigated by X-ray diffraction and Mossbauer spectroscopy measurements. Evidence for superparamagnetic relaxation of fine particles, both in the surfactant assisted ball-milled samples and in samples dry-milled in air is obtained from the room temperature and 4.2 K Mossbauer spectra. The similarity between samples milled at pH 3 with the cationic or anionic surfactants is due to electrostatic interactions of the surfactants' hydrocarbon groups with the positively charged barium ferrite surface