Te-125 mossbauer-spectroscopy study of some rare-earth monotelluride based solid-solutions
Ravot, D × Merah, S Percheronguegan, A Olivierfourcade, J Jumas, Jc Moubtassim, Mle Langouche, Guido #
Elsevier science sa lausanne
Journal of alloys and compounds vol:225 issue:1-2 pages:185-189
Mossbauer spectroscopy is a very suitable method to study very weak modifications of electronic states in the valence band. It probes the local environment of the central atom. The isomer shift (delta) measures the s electron density on the nucleus and the quadrupolar interaction (Delta) is an indicator of the asymmetry of the electron distribution. The line width (Gamma) of the Mossbauer absorption provides details about the order and site distribution in the material. Yb1-xEuxTe, Pb1-xEuxTe and Yb1-xGdxTe are f.c.c. solid solutions. They exist for 0 less than or equal to x less than or equal to 1. In these systems, with the exception of the trivalent gadolinium ion, all the cations are divalent. Te is in its divalent state. Eu2+ and Gd3+ carry a magnetic moment. All the other ions are non magnetic. YbTe and EuTe are large gap semiconductors; PbTe is a small gap one and GdTe is a metal. So, these solid solutions allow us to study the dilution of magnetism without any evolution of the nature of the ionic bond (Yb(Eu)Te), in a presence of a variation of the ionic character of the bond (Pb(Eu)Te) and in correlation with a semiconductor-metal transition (Yb(Gd)Te). These systems have been characterised by Te-125 Mossbauer spectroscopy. The x-dependence of the Mossbauer parameters is discussed with respect to the variation of the physical properties with composition in the different solid solutions.