Mössbauer study of bornite and chemical bonding in Fe-bearing sulphides

Abstract

© 2017 Springer-Verlag GmbH Germany The Mössbauer spectra of a nearly stoichiometric natural bornite, Cu 5 FeS 4 , specimen were reinvestigated between 295 and 4.2 K. There is no difference between the Neél temperature T N as determined by the Mössbauer effect or by the susceptibility measurements (T N = 67.5 K). No additional paramagnetic doublet can be observed in the low-temperature MS spectra. The valence state of Fe is Fe (3−x)+ caused by a partial electron transfer from the Cu + ions to the Fe 3+ ions which increases the shielding of the s-electrons by the d-electron density and by this increases the isomer shift to a value intermediate between tetrahedral high-spin Fe 2+ and tetrahedral high-spin Fe 3+ .