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Titolo:
STRUCTURAL AND HYDROGEN SORPTION STUDIES OF NDNI5-XALX AND GDNI5-XALX
Autore:
BOBET JL; PECHEV S; CHEVALIER B; DARRIET B;
Indirizzi:
UNIV BORDEAUX 1,CNRS,ICMCB,UPR 9048,INST CHIM MAT CONDENSEE BORDEAUX,162 AVE DR A SCHWEITZER F-33608 PESSAC FRANCE
Titolo Testata:
Journal of alloys and compounds
fascicolo: 1-2, volume: 267, anno: 1998,
pagine: 136 - 141
SICI:
0925-8388(1998)267:1-2<136:SAHSSO>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
ABSORPTION; SYSTEM;
Keywords:
STRUCTURAL TRANSITION; HYDRIDE; INTERMETALLICS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
13
Recensione:
Indirizzi per estratti:
Citazione:
J.L. Bobet et al., "STRUCTURAL AND HYDROGEN SORPTION STUDIES OF NDNI5-XALX AND GDNI5-XALX", Journal of alloys and compounds, 267(1-2), 1998, pp. 136-141

Abstract

Crystallographic and hydrogen sorption studies of the NdNi5-xAlx and GdNi5-xAlx systems have been carried out. It is found that up to x<2 the prototype hexagonal crystal structure of the CaCu5,-type is preserved. However, at x greater than or equal to 2, a larger unit cell of the HoNi2.6Ga2.4-type is observed. In both structures, a site preferenceoccupancy between Al and Ni atoms occurs. The structural transition with x is explained by considering steric effects: Al being bigger thanNi. All alloys were subjected to hydrogen sorption. The decrease of maximum hydrogen content and plateau pressure with increasing aluminiumcontent (from 4.1 H/f.u. and 0.87 MPa for GdNi4.5Al0.5 to 2.6 H/f.u. and 0.01 MPa for GdNi3.26Al1.74) is explained from both the thermodynamic and crystallographic point of view. These results are consistent with: (i) previous observations on the LaNi5-xAlx system and (ii) the 'Westlake criterium' except when the HoNi2.6Ga2.4 type structure appears. The huge decrease of the hydrogen content observed when the superstructure appears is explained by the change of possible hydrogen tetrahedral sites from RE2Ni2 to RE2Al2 (RE=Nd, Gd). (C) 1998 Elsevier Science S.A.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/03/20 alle ore 13:51:42