A Mossbauer study of the new phases Th4Fe13Sn5 and ThFe0.22Sn2

Two new phases Th4Fe13Sn5 and ThFe0.22Sn2 have been studied by Fe-57 and Sn -119 Mossbauer spectroscopy. The Fe-57 Mossbauer spectra of Th4Fe13Sn5, mea sured at room temperature and 4.2 Ii without and with applied magnetic fiel d up to 5.5 T, exhibit four sextets. Our measurements prove that all four F t: sub-lattices are collinear. The Sn-119 Mossbauer spectra of Th4Fe13Sn5 s how two sextets with different B-eff, reflecting the influence of ferromagn etic nn iron atoms. The results obtained from full-potential linear augment ed plane wave (LAPW) calculations are in agreement with the experimental da ta and confirm the assignment of Mossbauer spectra, The Mossbauer data for the ThFe0.22Sn compound prove the existence of two different sites both for Fe and Sn, all having icosahedral co-ordination. (C) 2001 Elsevier Science B.V, All rights reserved.