A new La2/3LixTi1-xAlxO3 solid solution:: Structure, microstructure, and Li+ conductivity

The stoichiometry range, crystal chemistry, ionic conductivity, and electrochemical window of the La2/3LixTi1-xAlxO3 system with perovskite-related structure have been studied. The range of the existence of the solid solution is (0.06 = x = 0.3). Powder X-ray diffraction and transmission electron microscopy results show that these oxides have a unit cell multiple of the perovskite cell with dimensions a approximate to root2a(p), b approximate to root2a(p), c approximate to 2a(p). The ionic conductivity of the materials and its dependence on composition and temperature have been examined by complex impedance spectroscopy. Lithium ion conductivity increases with increasing lithium content up to a value (7.6 x 10(-5) S cm(-1) at room temperature) corresponding to x = 0.25. Electrochemical experiments indicate that these materials can be used as solid electrolytes in secondary batteries having Li metal as the anode down to 1.6 V.