A model for the anomalous electronic properties in liquid silver chalcogenides

The electronic conductivity in liquids Ag–S and Ag–Se systems exhibits a maximum and a negative temperature derivative at the stoichiometric composition Ag₂S and Ag₂Se. In a similar alloy, Cu chalcogenides and other liquid semiconductors, such anomalies have not been observed. In the present paper, a model that explains the origin of the anomaly is presented. It is suggested that the anomalous behavior is controlled by the connection between the second nearest neighbor orbitals. Such connection depends on the electronegativity difference between the constituent elements of the system and is intimately related with the superionic behavior that these materials exhibit in the solid phase.