Growth and ionic conductivity of Li3 + x P1 − x GexO4 (x = 0.34) single crystals

Li3 + x P1 − x GexO4 crystals (x = 0.34) with dimensions of about 3 × 3 × 5 mm3 were grown for the first time from flux. The conductivities of the crystals measured along three directions have close values and are equal to σ ≈ 1.8 × 10−6 and 3.7 × 10−2 Sm/cm at the temperatures 40 and 400°C, respectively (similar to the case of pure lithium phosphate, somewhat lower values of electric conductivity were measure along the b axis). The activation energy of conductivity is equal to 0.54 eV. A considerable increase in the conductivity of the solid solution in comparison with the conductivity of pure lithium phosphate is explained by the specific features of the lithium sublattice in the crystal structure of the λ-Li3PO4 type.