Local environment of tin in layered SnSe2xS2(1−x) compounds by 119 Sn Mössbauer spectroscopy

The local environment of tin atoms in ${\mathrm{SnSe}}_{2x}{\mathrm{S}}_{2(1\ensuremath{-}x)}$ ($x=0--1)$ solid solutions has been studied by ${}^{119}$Sn M\"ossbauer spectroscopy. A linear increase of the M\"ossbauer isomer shift \ensuremath{\delta} as a function of $x$ is observed. First, we show that this result is in good agreement with a tight-binding evaluation of the M\"ossbauer isomer shift which takes into account the experimental values of the lattice parameters. Then, we propose a molecular calculation which provides a rather simple explanation of the linear relationship of \ensuremath{\delta} and $x$ based on the description of the local Sn environment.