Nb K-edge Extended X-ray Absorption Fine Structure spectroscopy (EXAFS), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to analyse the Nb coordination and phase formation in Nb-doped (5 at. %) h-Mg film samples deposited by r.f. magnetron sputtering. Results show that the catalytic effect of the Nb doping in the H2 absorption and desorption kinetics is connected with the formation of Nb nano-clusters dispersed in the host matrix. The H2 desorption from b-MgH2 is favoured by the elastic stress produced by b-NbH0.89 clusters on the MgH2 matrix that reduces the stability of the hydride phase and by preferential paths in the nanocomposite hydride.
Nb clusters formation in Nb-doped magnesium hydride / R., Checchetto; N., Bazzanella; A., Miotello; C., Maurizio; F., Dacapito; Mengucci, Paolo; Barucca, Gianni; Majni, Giuseppe. - In: APPLIED PHYSICS LETTERS. - ISSN 0003-6951. - 87:6(2005), pp. 61904-1-61904-3. [10.1063/1.2007866]