Li4GeO4-Li2CaGeО4 phase equilibria and Li2+xCa1-xGeO4 solid solutions

Detailed studies of the Li 4 GeО 4 -Li 2 CaGeО 4 system by solid-phase syntheses of various compositions from pure Li 4 GeО 4 to pure Li 2 CaGeО 4 in the temperature range from 25 to 1125 °C is investigated for a first time. Solid state synthesis powders are characterized by X-ray and DSC/TG methods. Concentration and temperature two-phase regions of Li 4 GeО 4 and Li 2 CaGeО 4 as well as two-phase regions of Li 2 CaGeО 4 and Li 2+2x Ca 1-x GeO 4 are established. Region of pure Li 2+2x Ca 1-x GeO 4 solid solution are detected too and it structure is investigated. Being structural analog to Li 2+2x Zn 1-x GeO 4 and Li 2+2x Mg 1-x GeO 4, Li 2+2x Ca 1-x GeO 4 has own specific local environment of the metal ions. The obtained results are compared with those for Li 4 GeО 4 -Li 2 ZnGeО 4 system and for Li 2+2x Zn 1-x GeO 4 solid solution. The differences of the phase diagrams and structural features of the solid solutions are discussed.