Preparation and ionic conductivity of Al-Doped Mg 0.5Ti 2(PO 4) 3

Abstract

Al-doped Mg0.5(1+x)AlxTi2 -x(PO4) 3 has been prepared by a solgel 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, 1015 mol%Al was used, resulting in lattice contraction in the c-axis direction. The samples, sintered at 500800° C for 12 h by a reaction sintering method, had a relative density of 7080% and their grain size was 23 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 1.304nm 3. © 2012 The Japan Institute of Metals.