Synthesis, structural characterization, thermal stability and electrical properties of the new phases MIGa(CrO4)2 (MI=Na, K, Rb)

Abstract

New phases of composition M^IGa(CrO₄)₂ (M^I=Na, K or Rb) have been synthesized by solid state reaction in air. The crystallograhic data of the three compounds have been refined by the Rietveld method. They all show a layer structure, the layer being formed of GaO₆ octahedra linked to CrO₄tetrahedra by sharing corners. Alkali metal ions lie in the interlayer space. The three compounds are thermally stable up to 300 °C, but above this temperature they decompose evolving oxygen. Impedance measurements show that they are ion conductors, the ionic conductivity being highest for the Na compound.