THE ELECTRICAL HYPERFINE PARAMETERS IN SYNTHETIC ALUMINOGOETHITES

The effects of the aluminum substitution and degree of crystallinity u pon the lattice-dynamical and electrical properties of synthetic goeth ites are determined from their Mossbauer spectra. The temperature vari ations of the centre shift could be calculated using the Debye approxi mation for the lattice vibrations. The parameters incorporated in this model exhibit a maximum at a certain aluminum content within each of the four series in this study. It has been found that the principal ax is of the EFG remains perpendicular to the direction of the magnetic h yperfine held when the aluminum content and/or the crystallinity chang e.