| Popis: |
Single crystals of monoclinic 4C-type pyrrhotite (Fe 7 S 8 ) with Fe/S ratios of 0.879, 0.872 and 0.867, have been grown, and oriented slices have been examined by Mossbauer spectroscopy, both with and without an applied external magnetic field. Four component spectra were distinguished corresponding to the four sites in the Bertaut model. Over the composition range examined, gradual minor variations from this model were observed, and it is concluded that the ordered defect structure occurs over a range of composition. The isomer shift of iron in the four sites is typical of divalent iron, this indicates delocalisation of the electron-hole. The orientation of the spins of the various iron sites were obtained from the relative intensity of the absorption lines in each component spectrum. The spins gradually cant out of the c-plane at room temperature and below. |
