材料期刊网

From the theoretical calculations of the spin-lattice coupling coefficients \G11\ and \G44\ for Fe3+ replacing an Al3+ ion of the (AlO4)5- group with the cubic symmetry approximation, we find that the observed values of \G11\ and \G44\ for the Fe3+ ion in an andalusite crystal show good agreement with these calculated values. Hence, we think that the Fe3+ ion occupies a distorted fourfold coordinated site in this crystal. This opinion supports a recent reinvestigation of the andalusite crystal structure in which, unlike in previous studies, a fourfold coordinated site of the Al3+ ion was proposed. It appears that the investigation of spin-lattice coupling coefficients are sometimes capable of determining the substitution position of 3d5 ions in crystals and detecting errors in crystal structure determinations.