Partial Electronic Conductivity and Chemical Diffusivity of Li3xLa2/3?xTiO3 Solid Solution

Partial electronic conductivity and chemical diffusivity of Li have been measured on the system of Li3xLa2/3−xTiO3 (LLT) with x = 0.13, a prospective Li+ electrolyte, against oxygen activity in the range of 10−22 < aO2 < 0.21 at 557∘, 610∘ and 663∘C, respectively by an ion-blocking polarization technique. It is found that the electronic conductivity of LLT, which in air is essentially an ionic conductor, varies as aO2−1/4 to render it mixed-conductive in reducing atmospheres, say, in aO2 < 10−12. The chemical diffusivity of component Li also increases from a value of the order of 10−8 cm2/s in air atmosphere up to a maximum on the order of 10−3 cm2/s as the electronic conductivity increases with decreasing oxygen activity. This is attributed to the variation of the electronic transference number and the thermodynamic factor with oxygen activity. The latter has been evaluated to be on the order of 10–103.