“…Recently TiN [4], CrN [5], GaN [6] and ZrN [7] have been intensively investigated in synthetic methods, structural characterization and applications. As one important member of metal nitrides, tungsten nitrides (W x N) have many promising properties, including good chemical stability, high strength, high hardness, high melting point with good electrical conductivity and a relative low band gap (2.2 eV) [8][9][10].…”