Morphologic and crystallographic studies on electrochemically formed chromium nitride films

Chromium nitride films were prepared by anodically oxidizing nitride ions at 0.4-1.5 V versus Li⁺/Li on chromium substrates in molten LiCl-KCl-Li₃N systems at 723 K. A crystalline Cr₂N film was successfully prepared at 0.4-1.4 V, and was thicker at more positive electrolytic potential. At 1.5 V, a Cr-N film could be also obtained, but its growth rate was relatively low. The film prepared at 1.5 V consisted of two distinctive layers. The surface layer was amorphous Cr-N containing crystalline CrN particles, and the inner layer was crystalline CrN. It was considered the existence of the amorphous phase suppressed the film growth.