Conductivity and solid state 29Si NMR studies of apatite-type lanthanum silicate prepared by hydrothermal method

Apatite-type lanthanum silicates are of great interest because of their high ionic conductivity in which it is potential to be used as electrolyte for the solid oxide fuel cell (SOFC) application. In the present work, we report ²⁹Si solid state NMR studies of several doped lanthanum apatite silicates prepared by hydrothermal method. For the undoped apatite La_9.33Si₆O₂₆ three peaks are observed at chemical shifts of ~-77.8, -80.5 and -82.5 ppm, and doped apatite two peaks are observed at chemical shifts of ~-77 and 78-80.5 ppm, apatite with the more high conductivity show more complex Si NMR spectra. That is indicating a correlation between the silicon environment and the observed conductivity.