Cation mobility in the Cu6PS5X (X=Cl, Br, I) argyrodites Original Research Article

The electrical conductivity of Cu6PS5Cl shows purely Arrhenius behavior throughout the temperature range 170–450 K with no evidence of the 241 K thermodynamic phase transition previously reported. Cu6PS5Br exhibits two changes in activation energy. The first, at 251 K, apparently coincides with a previously determined thermodynamic transition. The second, at 321 K, is likely associated with a conduction transformation from ionic to electronic. The conductivity of Cu6PS5I is characterized by a cusp at a temperature of 194 K, far removed from a previously reported thermodynamic transition at 221 K. In addition, a broad and continuous change in activation energy appears to coincide with another previously reported phase transition at 270 K.