ELECTRIC-FIELD GRADIENT OF IRON IN OXIDE GLASSES

Fe-57 Mossbauer spectroscopy has been carried out at room temperature on oxide glasses of the binary oxide systems, i.e., BaO-Fe2O3, SrO-Fe2O3, PbO-Fe2O3 and TeO2-Fe2O3 in order to estimate the distribution of electric field gradient of Fe3+ ion sites in these materials. The Mossbauer spectra obtained experimentally were reproduced by taking into account an asymmetric non-Gaussian distribution of electric field gradient around Fe3+ ions. From the analyses, the average value of the electric field gradient was evaluated for each glass. The average electric field gradient tends to increase monotonically with an increase in concentration of Fe3+ ions, irrespective of kinds of glass systems. It is thought that in the present oxide glasses with larger concentration of Fe3+ ions, more distorted local structure is required for Fe3+ ions to take a random state.