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Thermal aging of LaNi{sub 5-x}Mn{sub x} hydrides

Conference ·
OSTI ID:442172
; ;  [1]
  1. Univ. of Nevada, Reno, NV (United States); and others
The LaNi{sub 5-x}Mn{sub x}-hydrides have potential applications in cryocooling devices for non-mechanical method to compress hydrogen gas. Thermal aging behavior of LaNi{sub 5-x}Mn{sub x}-hydrides of compositions x=0.4 and x=1.5 has been investigated. The hydriding properties of the La{sub 1.02}Ni{sub 4.6}Mn{sub 0.4} alloy do not change significantly after thermal aging at 453K for 260 hours. X-ray diffraction analyses of this aged alloy do not reveal the presence of any new phases but the Bragg peaks become broader. Line profile analyses show anisotropic microstrains with an average {sup 1/2} value of {approximately}5x10{sup -3}. Thermal aging of the other hydride, LaNi{sub 3.5}Mn{sub 1.5} hydride, at 623K for 280 hours, showed significant disproportionation; the hydrogen capacity reduced significantly from an H/M value of 0.75 in the activated condition to {approximately}0.15 after aging. X-ray diffraction analyses showed disproportionated lanthanum dihydride, metallic Ni, and Mn phases. The Bragg peaks were very broad indicative of microstrains or small crystalline domains.
Research Organization:
Los Alamos National Lab., NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
442172
Report Number(s):
LA-UR--96-4084; CONF-970201--11; ON: DE97003128
Country of Publication:
United States
Language:
English