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.