Investigation of new lithium ionic conductors Li+xV1−xSixO4

A continuous solid solution Li3+xV1−xSixO4 has been found at high temperature in the system Li4SiO4−Li3VO4. At room temperature the solid solution ranges fromx = 0.1 tox = 0.5. This solid solution is formed by stabilizing the high temperature ψII-phase of Li3VO4 which the addition of Li4SiO4. Of compositions studied, Li3.3V0.7Si0.3O4 has the highest conductivity, reaching 1×10-5 Ω-1 cm at room temperature and having an activation energy of 0.36 eV in the temperature range 42–192°C. The NMR linewidth of7Li in this material was measured at different temperatures. Motional narrowing has been observed near -20°C. It is suggested that Li+ ions are the mobile species. The high conductivity domains in the pseudo-ternary system Li4GeO4−Li4SiO4−Li3VO4 have been roughly determined.