Structural and optical properties of magnesium nitride formed by a novel electrochemical process

The electrochemical formation of magnesium nitride (Mg3N2) films in LiCl-KCl containing Li3N at 723 K was investigated. From a thermodynamic point of view, a potential-pN3− diagram was constructed for the Mg-N system in an analogous fashion to Pourbaix diagrams for aqueous solutions. As a result, the thermodynamically stable region of Mg3N2 in LiCl-KCl-Li3N was identified. XRD analysis revealed that Mg3N2 film was obtained by potentiostatic electrolysis of a magnesium electrode between 0.4 and 0.8 V (versus Li+/Li), and the structure of obtained Mg3N2 was anti-bixbyite (a = 1.001 nm). Reflectance measurements clarified that assuming direct transition, the bandgap energy was 3.15 eV and assuming indirect transition, the bandgap energy was 2.85 eV.