Sodium superionic conductor sputter-deposited coatings

Thin sodium superionic conductor (Nasicon) coatings are deposited on rotating substrates by co-sputtering in the reactive mode of a Zr-Si and a Na3PO4 target. The influence of the discharge current and of the target-to-substrate distance is investigated owing to the targeted Na3Zr2Si2PO12 stoichiometry. A thermo-structural analysis shows that the amorphous as-deposited coating of convenient composition crystallises around 700 °C in the monoclinic structure. Electrical measurements performed at room temperature after various annealing treatments indicate a ionic conductivity of about 2·10−3 S·cm−1, consistent with that of bulk Nasicon.