Relationship between the local electronic and local crystal structures of intermediate-valence Sm1−xYxS

The valence state of samarium and the local environments of samarium and yttrium ions in the intermediatevalence compound Sm_1−x Y _x S (x = 0.17, 0.25, 0.33, or 0.45) are studied over a wide temperature range of 20–300 K using x-ray absorption spectroscopy. The temperature dependence of Sm-S, Sm-Sm(Y), Y-S, and Y-Sm(Y) bond lengths and the Debye-Waller factors has been found. A direct correlation of changes in the valence of samarium with changes in its local environment parameters depending on yttrium concentration and temperature has been revealed. The main characteristics of the intermediate-valence state of samarium have been determined: the energy width of the 4f level and its position with respect to the Fermi level.