High lithium ionic conductivity in the garnet-type oxide Li7−X La3(Zr2−X, NbX)O12 (X = 0-2)

(a) Temperature dependence of lithium ion conductivity of Li7−XLa3(Zr2−X, NbX)O12 (X = 0-2) samples. (b) Lithium ion conductivity at 25 ̊C and activation energy as a function of Nb content. The solid lines are provided as visual guides.