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

Electronic and ionic conductivities of silver selenide crystal (Ag<SUB>2+&#948;</SUB>Se) have been measured over a range of stoichiometry through the &#945;-&#946; transition by using solid state electrochemical techniques. In the high temperature &#946;-phase Ag<SUB>2</SUB>Se shows metallic behaviour of electronic conductivity for high values of &#948;; with decrease in &#948;, the conductivity of the material exhibits a transition. The magnitude of change in electronic conductivity at the &#945;-&#946; transition is also determined by stoichiometry. Ionic conductivity of the &#946;-phase does not vary significantly with stochiometry. Ionic conductivity of the &#946;-does not vary significantly with stoichiometry. A model to explain the observed transport properties has been suggested