Fig. 1: Entropy of cation site in rocksalt structure (Ag,Sn)Se2−.
a The rocksalt structure of (Ag,Sn)Se shown on the left side, and the two possible charge distributions on the Ag/Sn site are shown on the right. Top right shows the Sn2+/Sn4+ distribution, and bottom right shows the Sn2+/Sn3+ distribution, along the formulae dependence on x. b The entropy of mixing δSmix for different numbers of components, n = 2, 3, sharing the same site as a function x for a single component with all other components being equal. The mixing δSmix considering the charge entropy as a function of x for the case of Sn2+/Sn4+/Ag+1 and Sn2+/Sn3+/Ag+1 are shown for comparison. c A zoomed in result of (b) where the stability region of AgxSn1−xSe is highlighted with filled region around the peak of the curve for Sn2+/Sn4+/Ag+1 entropy.
