24621-21-4

dark gray; fcc, a=0.4388nm; hardness, 8+ Mohs; electrical resistivity 78μοhm· cm; transition temp 15.2K; can be prepared by heating Nb metal in excess N2 or NH3 to 700°C–1100°C; used in the form of 99.5% pure sputtering target for increasing electrical stability of diodes, transistors, and integrated circuits [KIR81] [CIC73] [CER91]

Dark gray crystals. Transition temperature 15.2 K. Insoluble in HCL, HNO₃ and H₂SO₄; but attacked by hot caustic, lime, or strong alkalis evolving NH₃.