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Hydrogen diffusion in bulk and nanoclusters of MgH2 and the role of catalysts on the basis of ab initio molecular dynamics
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. (Condensed Matter Theory Grp)
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. (Condensed Matter Theory Grp)
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. (Condensed Matter Theory Grp)
2009 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, no 22, 221910- p.Article in journal (Refereed) Published
Abstract [en]

We present ab initio molecular dynamics calculations based on density functional theory to study the hydrogen-deuterium exchange in bulk and nanoclusters of MgH2. Our calculations reveal the important role of catalysts to diffuse the hydrogen at low temperatures and increase the diffusion rate. We determine the diffusion constants, < D > of deuterium, and show the single hydrogen-deuterium exchange in bulk and nanocluster of MgH2. Our calculated value of diffusion constant of deuterium in bulk MgH2 is in excellent agreement with the experimental value. Furthermore, we show the edge site importance of catalysts in the fast diffusion of hydrogen.

Place, publisher, year, edition, pages
2009. Vol. 94, no 22, 221910- p.
Keyword [en]
ab initio calculations, catalysis, catalysts, chemical exchanges, density functional theory, diffusion, hydrogen storage, magnesium compounds, molecular dynamics method, nanostructured materials
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-129006DOI: 10.1063/1.3152250ISI: 000266674300023OAI: oai:DiVA.org:uu-129006DiVA: diva2:332433
Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12
In thesis
1. Structural, Electronic and Mechanical Properties of Advanced Functional Materials
Open this publication in new window or tab >>Structural, Electronic and Mechanical Properties of Advanced Functional Materials
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 98 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1062
Keyword
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
National Category
Physical Sciences
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-205243 (URN)978-91-554-8723-2 (ISBN)
Public defence
2013-09-27, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2013-09-06 Created: 2013-08-15 Last updated: 2014-01-08Bibliographically approved

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Ramzan, MuhammadHussain, TanveerAhuja, Rajeev

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