Hydrogen Absorption by LaCu sub 5 and NMR Studies of Hydrogen Diffusion in beta -LaCu sub 5 Hydride

摘要

The hydrogen absorption properties of LaCu sub 5 have been investigated using a well-characterized parent intermetallic prepared from high purity elements. When exposed to 36 atm H sub 2 at 374K this LaCu sub 5 specimen absorbed 3.7 H atoms per formula unit, which is over 20% larger than previously reported. Single plateau isotherms were obtained from pressure-composition measurements between 355 to 394K. The alpha -phase hydride retains the hexagonal structure of the parent intermetallic, but the beta -phase hydride is C-centered monoclinic. Hydrogen diffusion in LaCu sub 5 H/sub 3.4/ was investigated using pulsed NMR techniques to measure spin-lattice (T sub 1 ) and rotating frame (T sub 1 ) proton relaxation times. We present evidence for at least two uncoupled modes of diffusive motion that are substantially less rapid than previously reported for beta -LaNi sub 5 hydride. 25 refs., 2 figs., 3 tabs. (ERA citation 11:036423)