Synthesis and conductivities of the Ti-doped apatite-type phases La9.33Si6-xTixO26

Abstract

Solid oxide fuel cell is one of the alternative energy sources with high efficiency and low emissions. Solid oxide electrolyte is an important component of this fuel cell. A new electrolyte that suitable at medium temperature is needed to be developed. Apatite type lanthanum silicate is one of the electrolytes, which can operate at medium temperature. Increasing performance of apatite lanthanum silicate such as ionic conductivity can be achieved by doping. The purpose of the present study was to synthesize the electrolyte of Lanthanum silicates oxide with hydrothermal method and to investigate the effect of Ti4+ dopant on apatite electrolyte characteristics such as crystal lattice parameter and conductivity. The results showed that samples of La9.33Si6-xTixO26 with x = 0.1, 0.2, 0.3 were successfully synthesized. The value of c on the crystal lattice parameter increases with increasing the doping content of Ti4+. Increasing c value on the crystal lattice parameter is directly proportional to the conductivity. Apatite La9.33Si5.7Ti0.3O26 showed the highest conductivity of 2.4 × 10-4 S/cm at 700°C.