Synthesis and Conductivity of Oxyapatite Ionic Conductor La10−xVx(SiO4)6O3+x

Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity. In this paper, V-doped samples La10−xVx(SiO4)6O3+x (0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported. The samples were characterized by thermal analysis (TG-DSC), X-ray diffraction (XRD) and scanning electron micrograph (SEM). The apatite was obtained at 800 °C, a relatively low temperature in comparison to 1500 °C with the conventional solid-state method. The ceramic pellets sintered at 1200 °C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400 °C for 20 h. The conductivities of samples were measured by electrochemical impedance spectroscopy. The conductivity was improved with the increase of V-dopant content on La site.