Solid-state synthesis of potassium β- and β″-gallates

Direct synthesis of K-β- and β″-gallates by Ga2O3–K2O solid-state reaction is described. The formation of K-β- or β″-gallates depends on the initial Ga2O3 phase. α-Ga2O3 leads to K-β-gallate; β-Ga2O3 leads to K-β″-gallate. K-β″-Gallate is stable <1200°C. The high temperature stability of K-β″-gallate can be enhanced by doping with aliovalent ions.