Mechanochemical synthesis of niobium hydrides

The synthesis of niobium hydrides under ball milling of the pure Nb powder in hydrogen atmosphere or in the presence of H2O traces was investigated. It was shown by XRD method that niobium hydride is formed after 20 min of mechanical treatment in H-2 atmosphere. Niobium hydride has a cubic structure with the lattice parameter a = 0.34391nm, which is corresponded to the composition NbH1.01 and block size more than 100nm. There is broadening of peaks due to the increasing of average microstrain. The mechanical treatment during 5h in water presence leads to the formation of oxyhydride with the BCC structure (lattice parameter a = 0.3423 and block size similar to 15nm). The results of the hydrogen thermodesorption show that in the first case the NbH1.01 is transformed into Nb with the traces of NbO. In second case after the thermodesorption hydride phase is transformed completely into Nb8O.