2012 Volume 53 Issue 5 Pages 932-935
Al-doped Mg0.5(1+x)AlxTi2−x(PO4)3 has been prepared by a sol–gel method and the conductivity has been evaluated by an ac impedance method to determine the optimum lattice volume for Mg-ion conduction. Instead of using Ti in the samples, 10–15 mol%Al was used, resulting in lattice contraction in the c-axis direction. The samples, sintered at 500–800°C for 12 h by a reaction sintering method, had a relative density of 70–80% and their grain size was 2–3 µm. The ionic conductivity calculated from the grain and grain boundary resistance at 600°C was 7.1 × 10−5 and 1.3 × 10−5 S/cm, respectively. The activation energy of the grain conductivity was 128 kJ/mol in the temperature range of 300 to 600°C. By comparing ionic conductivity of various-doped titanium phosphates, optimum lattice volume was estimated to be 1.304 nm3.