Large atomic disorder in nanostructured LaNi alloys: A La L-edge extended X-ray absorption fine structure study

B. Joseph (1) , A. Iadecola (1) , B. Schiavo (2, 3) , N.L. Saini (1)

1 Dipartimento di Fisica
2 Istituto Tecnologie Avanzate
3 Dipartimento di Fisica e Tecnologie Relative

Local structure of the nanostructured LaNi5 alloys, prepared by ballmilling, has been studied using La L3-edge extended x-ray absorption fine structure spectroscopy. The near-neighbour distances tend to decrease with the ball-milling, and the mean square relative displacements (MSRD) show substantial increase suggesting an increased atomic disorder. High temperature annealing helps in partial recovery of atomic order in the ball-milled samples for milling times upto 20 h, however, the long-time ball-milled samples seems to gain only a local random order. The results suggest that reduced unit-cell volume together with large atomic-disorder might be causing a higher energy-barrier for the hydride-phase formation in the long time ball-milled LaNi5 powders.

Mots clés: LaNi5 alloys; Nanostructuring; Local structure; Atomic disorder

B. Joseph, A. Iadecola, B. Schiavo, N.L. Saini. Large atomic disorder in nanostructured LaNi alloys: A La L-edge extended X-ray absorption fine structure study. Journal of Physics and Chemistry of Solids, 2010, 71 (8), pp.1069. ⟨10.1016/j.jpcs.2010.03.008⟩. ⟨hal-00661910⟩