INVESTIGADORES
JUAN Alfredo
artículos
Título:
A theoretical study of H absorption at a Fe(110)Pd(100) interface and FePd alloys
Autor/es:
P. JASEN; E. GONZÁLEZ; N. J. CASTELLANI; A. JUAN
Revista:
JOURNAL OF MATERIALS SCIENCE
Editorial:
Springer Netherlands
Referencias:
Lugar: Amsterdam; Año: 2005 vol. 40 p. 2775 - 2782
ISSN:
0022-2461
Resumen:
The electronic structure and bonding at a Fe(110)Pd(100) interface was theoretically analyzed in the framework of semi-empirical quantum chemical calculations. The FePd interface was modeled by a Fe74Pd74 cluster and a FePd six layer slab. The extended H¨ uckel tight binding (EHTB) method and its modifications, including repulsive interactions, were used to calculate the interfacial adhesion and the H-absorption energy. The energetic minimum position for H is found at the FePd interface closer to the Pd layer. The interfacial FePd distance result to be 1.73 ° A where FePd develops a strong bonding interaction. An important metalmetal adhesion was also found. The changes in the Density of States (DOS) and the Crystal Orbital Overlap Population (COOP) were compared in different structures: clusters, slab and two types of FePd alloys. The H as an impurity is responsible for a FeFe and PdPd bond weakening. However, the H effect is much less detrimental for the FePd bonds at the interface. When H is located at interstitial sites in bulk FePd alloys, the PdPd overlap population shows a notorious decrease in the case of fcc structures while for fct structures the change is only 12%. The intermetallic bonding was also weakened as compared with the pure alloys. The objective of this work is to bring a plausible explanation to the null permeability to hydrogen in Pd-coated Fe films.e74Pd74 cluster and a FePd six layer slab. The extended H¨ uckel tight binding (EHTB) method and its modifications, including repulsive interactions, were used to calculate the interfacial adhesion and the H-absorption energy. The energetic minimum position for H is found at the FePd interface closer to the Pd layer. The interfacial FePd distance result to be 1.73 ° A where FePd develops a strong bonding interaction. An important metalmetal adhesion was also found. The changes in the Density of States (DOS) and the Crystal Orbital Overlap Population (COOP) were compared in different structures: clusters, slab and two types of FePd alloys. The H as an impurity is responsible for a FeFe and PdPd bond weakening. However, the H effect is much less detrimental for the FePd bonds at the interface. When H is located at interstitial sites in bulk FePd alloys, the PdPd overlap population shows a notorious decrease in the case of fcc structures while for fct structures the change is only 12%. The intermetallic bonding was also weakened as compared with the pure alloys. The objective of this work is to bring a plausible explanation to the null permeability to hydrogen in Pd-coated Fe films.