A single crystal study of the defect chemistry and transport properties of silver selenide, Ag _{2 + <i>δ</i>} Se

Electronic and ionic conductivities of silver selenide crystal (Ag 2 + δ Se) have been measured over a range of stoichiometry through the α-β transition by using solid state electrochemical techniques. In the high temperature β-phase Ag 2 Se shows metallic behaviour of electronic conductivity for high values of δ ; with decrease in δ, the conductivity of the material exhibits a transition. The magnitude of change in electronic conductivity at the α -β transition is also determined by stoichiometry. Ionic conductivity of the β-phase does not vary significantly with stoichiometry. A model to explain the observed transport properties has been suggested.