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Correlation effects in the electronic and structural properties of Cr2AlC
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
2011 (engelsk)Inngår i: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 5, nr 3, s. 122-124Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In this Letter, we present the electronic and structural properties calculated by first principles GGA and GGA+U calculations of Cr2AlC, a member of the MAX phases family of compounds. While GGA fails to obtain a correct description, the GGA+U method successfully reproduces the experimental equilibrium volume and bulk modulus values of Cr2AlC, and predict it to be a ferromagnet. Therefore, correlation effects are crucial for the correct description of Cr2AlC, provided that a suitable value of U is chosen.

sted, utgiver, år, opplag, sider
2011. Vol. 5, nr 3, s. 122-124
Emneord [en]
MAX phases, ab-initio calculations, GGA plus U, correlations
HSV kategori
Identifikatorer
URN: urn:nbn:se:uu:diva-157668DOI: 10.1002/pssr.201004508ISI: 000288178800012OAI: oai:DiVA.org:uu-157668DiVA, id: diva2:436094
Tilgjengelig fra: 2011-08-22 Laget: 2011-08-22 Sist oppdatert: 2017-12-08
Inngår i avhandling
1. Structural, Electronic and Mechanical Properties of Advanced Functional Materials
Åpne denne publikasjonen i ny fane eller vindu >>Structural, Electronic and Mechanical Properties of Advanced Functional Materials
2013 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The search for alternate and renewable energy resources as well as the efficient use of energy and development of such systems that can help to save the energy consumption is needed because of exponential growth in world population, limited conventional fossil fuel resources, and to meet the increasing demand of clean and environment friendly substitutes. Hydrogen being the simplest, most abundant and clean energy carrier has the potential to fulfill some of these requirements provided the development of efficient, safe and durable systems for its production, storage and usage.

Chemical hydrides, complex hydrides and nanomaterials, where the hydrogen is either chemically bonded to the metal ions or physiosorbed, are the possible means to overcome the difficulties associated with the storage and usage of hydrogen at favorable conditions. We have studied the structural and electronic properties of some of the chemical hydrides, complex hydrides and functionalized nanostructures to understand the kinetics and thermodynamics of these materials.

Another active field relating to energy storage is rechargeable batteries. We have studied the detailed crystal and electronic structures of Li and Mg based cathode materials and calculated the average intercalation voltage of the corresponding batteries. We found that transition metal doped MgH2 nanocluster is a material to use efficiently not only in batteries but also in fuel-cell technologies.

MAX phases can be used to develop the systems to save the energy consumption. We have chosen one compound from each of all known types of MAX phases and analyzed the structural, electronic, and mechanical properties using the hybrid functional. We suggest that the proper treatment of correlation effects is important for the correct description of Cr2AlC and Cr2GeC by the good choice of Hubbard 'U' in DFT+U method.

Hydrogen is fascinating to physicists due to predicted possibility of metallization and high temperature superconductivity. On the basis of our ab initio molecular dynamics studies, we propose that the recent claim of conductive hydrogen by experiments might be explained by the diffusion of hydrogen at relevant pressure and temperature.

In this thesis we also present the studies of phase change memory materials, oxides and amorphization of oxide materials, spintronics and sulfide materials.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2013. s. 98
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1062
Emneord
DFT, Hydrogen storage, Rechargeable batteries, Amorphization, Electronic structure, Crystal strcuture, Molecular dynamics, Diffusion, Intercalation voltage, High pressure, MAX phases, Mechanical properties, Optical properties, Phase change memory, Spintronics, Magnetism, Correlation effects, Band structure
HSV kategori
Forskningsprogram
Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-205243 (URN)978-91-554-8723-2 (ISBN)
Disputas
2013-09-27, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2013-09-06 Laget: 2013-08-15 Sist oppdatert: 2014-01-08bibliografisk kontrollert

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