Ag9I(GeO4)2 – Containing Two‐dimensionally Linked [IAg12] Metallo Complexes

Ag₉I(GeO₄)₂ was obtained for the first time by reacting a stoichiometric mixture of Ag₂O, AgI, and GeO₂, at elevated oxygen pressures, adding a small portion of distilled water. The synthesis was done at 480 °C and 110 MPa of oxygen pressure. It crystallizes in space group C2/m, with the unit cell dimensions a = 17.3736(9) Å, b = 6.9177(4) Å, c = 5.7176(3) Å, β = 105.501(3)°, V = 662.18(6) ų, and Z = 2. The structure refinement was based on 638 independent reflections and resulted in R₁ = 6.26 %. The crystal structure consists of isolated (GeO₄)^4– ions and IAg₁₂] metallo complexes, the latter are interconnected through each two common edges and corners corresponding to IAg_6/1Ag_6/2], thus forming infinite layers within the (100) plane. The Ag/I slabs are stacked perpendicular to the a‐axis with an interlayer distance of about 3.4 Å. The (GeO₄)^4– anions are located in the gaps between the silver iodide layers. According to the results of impedance measurements, Ag₉I(GeO₄)₂ is a good silver ion conductor. The compound shows an increase in the ionic conductivity in the temperature range of 30 to 310 °C, and has a silver ion conductivity of 1.1 × 10^–3 Ω^–1 cm^–1 at room temp. The activation energy for silver ion conduction is 0.35 eV, in the temperature range from 25 to 190 °C.