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Role of correlation and relativistic effects in MAX phases
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
2012 (engelsk)Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 47, nr 21, s. 7615-7620Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We have performed the ab initio calculations to study the role of correlation and relativistic effects in MAX phases. As of now, there are more than 50 MAX phases reported in the literature; however, we have chosen two MAX phases, namely Cr2AlC and Ta2AlC, as representatives of MAX phases for our study as they are very poorly described from calculation point of view. Our results show that correlation effects are very important to understand the electronic and mechanical properties of Cr2AlC, but not so important for Ta2AlC. We have also studied the relativistic effects on Ta2AlC and our calculations show that going from scalar to fully relativistic effects does not have any significant effect on the electronic and mechanical properties of Ta2AlC. We conclude that Ta2AlC is a weakly correlated system, whereas Cr2AlC is a strongly correlated system. Further experiments are needed to explain the discrepancy between theory and experiments.

sted, utgiver, år, opplag, sider
2012. Vol. 47, nr 21, s. 7615-7620
Emneord [en]
Generalized Gradient Approximation, Initio Molecular-Dynamics, Band-Structure, Ti3sic2, Cr, Transition, Solids, Ta2alc, Energy, Ta
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-102336DOI: 10.1007/s10853-012-6609-6ISI: 000307520900026Scopus ID: 2-s2.0-84865248947OAI: oai:DiVA.org:kth-102336DiVA, id: diva2:552491
Forskningsfinansiär
Swedish Research Council
Merknad

QC 20120914

Tilgjengelig fra: 2012-09-14 Laget: 2012-09-14 Sist oppdatert: 2017-12-07bibliografisk kontrollert
Inngår i avhandling
1. Heavy Metal Compounds and Hydrogen Storage Materials from Ab Initio Calculations
Åpne denne publikasjonen i ny fane eller vindu >>Heavy Metal Compounds and Hydrogen Storage Materials from Ab Initio Calculations
2013 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

In principle, most of the properties of solids can be determined by their electronic structures. So the understanding of electronic structures is essential. This thesis presents two classes of materials using ab initio method based on density functional theory. One is heavy metal compounds like Ta2AlC, ThO and the other one is hydrogen storage material namely MgH2 surfaces.

The study of correlation and relativistic effects in Ta2AlC are presented. Based on our results, Ta2AlC is a weakly correlated system. Our study shows that the spin - orbital coupling does not play a very important role where as the other relativistic corrections such as mass velocity and Darwin terms have a significant effect on the electronic properties.

The stability of rock salt like ThO has been proposed based on the first principle calculation. ThO can be stabilized under pressure. The driving force is the sd to f charge transfer in Th.

We have investigated the energetics of hydrogen desorption from the MgH2 (110) and (001) surfaces. The doping of foreign metal elements and strain were used to reduce the dehydrogenation energy. The reduction in dehydrogenation energy is caused by the charge localization on the metal atoms which leads to destabilization and the weakening of metal - hydrogen bonds.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2013. s. vii, 32
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-120062 (URN)978-91-7501-675-7 (ISBN)
Presentation
2013-04-10, Sal M131, Brinellvägen 23, KTH, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20130327

Tilgjengelig fra: 2013-03-27 Laget: 2013-03-27 Sist oppdatert: 2013-03-27bibliografisk kontrollert

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