MOSSBAUER STUDY ON THE DISTRIBUTION OF IRON IN HIGH COERCIVITY CHROMIUM DIOXIDE PARTICLES

Fe-57 Mossbauer spectroscopy is applied to determine the level of iron doping in newly developed high coercivity CrO2 particles. It is found that, compared with the conventional preparation process, the new particles contain an increased amount of Fe3+ ions in the CrO2 crystal lattice giving rise to higher magnetocrystalline anisotropy. This is reflected in coercivities up to over 900 Oe. All samples contain as a secondary iron-containing phase some (Cr1-xFex)2O3. The valency of the iron doping is predominantly +3; very weak signals in the Mossbauer spectra suggest the existence of Fe4+ in an amount of 2-3% of the total number of iron atoms.