First-Principles Study of Superabundant Vacancy Formation in Metal Hydrides.
Recent experiments have established the generality of superabundant vacancies (SAV) formation in metal hydrides. Aiming to elucidate this intriguing phenomenon and to clarify previous interpretations, we employ density-functional theory to investigate atomic mechanisms of SAV formation in fcc hydrid...
| Publicado en: | Journal of the American Chemical Society Vol. 127; no. 27; pp. 9808 - 9818 |
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| Autores principales: | , |
| Formato: | Artículo |
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American Chemical Society
7/13/2005
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=17658305&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 17658305 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 7/13/2005 vid: 127 iid: 27 pid: 997 pub: American Chemical Society artinfo: ui: 17658305 10.1021/ja050475w ppf: 9808 ppct: 10 formats: tig: atl: First-Principles Study of Superabundant Vacancy Formation in Metal Hydrides. aug: au: Changjun Zhang Alavi, Ali affil: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 JEW, United Kingdom. su: Hydrides Density functionals Hydrogen Entropy Alloys Metals Functional analysis sug: subj: Hydrides Density functionals Hydrogen Entropy Alloys Metals Functional analysis ab: Recent experiments have established the generality of superabundant vacancies (SAV) formation in metal hydrides. Aiming to elucidate this intriguing phenomenon and to clarify previous interpretations, we employ density-functional theory to investigate atomic mechanisms of SAV formation in fcc hydrides of Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au. We have found that upon H insertion, vacancy formation energies reduce substantially. This is consistent with experimental suggestions. We demonstrate that the entropy effect, which has been proposed to explain SAV formation, is not the main cause. Instead, it is the drastic change of electronic structure induced by the H in the SAV hydrides, which is to a large extent responsible. Interesting trends in systems investigated are also found: ideal hydrides of 5d metals and noble metals are unstable compared to the corresponding pure metals, but the SAV hydrides are more stable than the corresponding ideal hydrides, whereas opposite results exist in the cases of Ni, Rh, and Pd. These trends of stabilities of the SAV hydrides are discussed in detail and a general understanding for SAV formation is provided. Finally, we propose an alternative reaction pathway to generate a SAV hydride from a metal alloy. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2005 holdings: @attributes: islocal: N |
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