ATS Scattering from the Tetrahedral and Octahedral Site in Magnetite and Franklinite

概要

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The pre-edge peak as well as the main peak just above the Fe K-absorption edge is observed for anisotropic tensor of susceptibility (ATS) scattering in magnetite, Fe_3O_4 (inverse spinel structure). In order to investigate the origin of the peaks, we study the ATS scattering in franklinite, ZnFe_2O_4 (normal spinel structure) which has Zn atoms in the tetrahedral A sites and Fe atoms in the octahedral B sites. In franklinite, only the main ATS peak is observed at almost the same energy as magnetite. Therefore, the pre-edge and main peaks of magnetite originate from the A and B site atoms, respectively. Because the dipole transition of A site atoms cannot excite ATS scattering, the dipole-quadrupole transition is investigated. The observed energy spectra for the (002) and (006) reflections in magnetite reveal that the pre-edge peak is due to the dipole-quadrupole transition of Fe atoms in the A sites. Comparing the main peak intensities of both reflections in magnetite and franklinite, we conclude that the main peak in franklinite is caused by dipole transition of the B site atoms. However the contribution of dipole-quadrupole transition is presumed in magnetite.
2002-07-15