La-Si metallic coatings were synthesized by Direct Current Magnetron Sputtering of lanthanum and silicon targets in pure argon atmosphere. After the deposition stage, the ceramic apatite-structure coatings were obtained by thermal oxidation in air. The structural and chemical features of these films have been assessed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The electrical properties were determined by complex impedance spectroscopy in planar configuration. The films with near lanthanum silicate La/Si atomic ratio deposited on porous Ni-YSZ cermet substrates were initially amorphous. After thermal oxidation at 1173 K in air, the coating crystallised under the expected apatite structure. SEM observation revealed that the film compactness and thickness increased after thermal oxidation. The electrical measurements carried out under air as a function of temperature (1173 to 723 K) show only one contribution for the apatite layer on the Nyquist diagram. This contribution is characteristic of the bulk materials response. The electrical properties were controlled by the Arrhenius law with an activation energy (E_a = 0.2 eV) slightly lower than that of the literature.
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