Synthesis, structure and conductivity of Ag₂ZnSiO₄, Ag₂ZnGeO₄ and Ag₂BeSiO₄

The compounds Ag₂MM′O₄ with MM′ = ZnSi, ZnGe and BeSi have been synthesised by reacting the corresponding Na compounds with molten AgNO₃. The crystal structures of Ag₂ZnSiO₄ and Ag₂ZnGeO₄ have been refined from Cu K α₁ powder diffractometer data by the Rietveld technique to R_F = 3.3 and 7.1%, respectively. They are isostructural with monoclinic Na₂ZnSiO₄. The powder pattern of Ag₂BeSiO₄ indicates that it is isostructural with orthorhombic Na₂BeSiO₄. The conductivity of the compounds has been determined using ac impedance measurements. Ag₂ZnSiO₄ and Ag₂BeSiO₄ are ionic conductors, with conductivities that are very similar to those of their corresponding isostructural Na compounds. Ag₂ZnGeO₄ is an electronic semiconductor with σ(60 °C) = 1.0 × 10^-2 (Ω cm)^-1.