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Water adsorption on ZnO(10(1)over-bar0): The role of intrinsic defects
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.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
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2012 (Engelska)Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 97, nr 1, s. 17014-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Density functional theory (DFT) calculations have been performed to investigate the interaction of water molecules with bare and defective ZnO(10 (1) over bar0) surfaces. We show that at high coverages water molecules avoid adsorption close to defect sites, whereas at low coverages adsorption on defective surfaces show a similar adsorption pattern to those adsorbed on the defect-free surface, adsorbing in a molecular fashion. Finally we show that the electronic structure of the defective non-polar surface is not much affected by the adsorption of water, with exception of the O-defect surfaces.

Ort, förlag, år, upplaga, sidor
2012. Vol. 97, nr 1, s. 17014-
Nationell ämneskategori
Fysik
Identifikatorer
URN: urn:nbn:se:uu:diva-170802DOI: 10.1209/0295-5075/97/17014ISI: 000300250800045OAI: oai:DiVA.org:uu-170802DiVA, id: diva2:509578
Tillgänglig från: 2012-03-13 Skapad: 2012-03-13 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
Ingår i avhandling
1. First-Principles Studies of Materials Properties: Pressure-Induced Phase Transitions & Functional Materials
Öppna denna publikation i ny flik eller fönster >>First-Principles Studies of Materials Properties: Pressure-Induced Phase Transitions & Functional Materials
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt) [Forskning på konstnärlig grund]
Abstract [en]

This thesis presents the first-principles studies of materials properties within the framework of the density functional theory (DFT). The thesis constitutes three main parts, i. e., pressure-induced phase transitions in solids, data-storage and clean-energy materials.

The first part focuses on the predictions of crystal structures and the determinations of electronic properties of Xe-H2, FeB4 and Co3O4. Pressurizing Xe-H2 compound yields the formation of H-rich Xe(H2)8, which can exhibit a metallic feature at comparatively lower pressure than pure hydrogen. Hard superconducting FeB4 gets transformed into a novel transparent phase under pressure owing to the enhanced overlap of atomic cores. Spinel Co3O4 undergoes the phase transition from a cubic to a monoclinic because of the charge transfer between cations via the increased 3d-3d interactions.

The second part involves the study of structural and electronic properties of phase-change memory materials (PCMs), i. e., Ge2Sb2Te5 (GST) and Ga-doped In2O3. Van der Waals (vdW) interaction must be considered to obtain accurate crystal structure of layered GST. For Ga-doped In2O3 (GIO), the local structure of amorphous GIO is found to resemble that of amorphous In2O3, except the vicinity of doping atoms. The electronic property of a-GIO is metallic, which considerably differs from the semiconducting feature of the crystalline GIO. This emphasizes the contrast in the conductivity of the crystalline and amorphous upon phase switching of GIO.

The third part associates with the search for clean-energy materials, viz., hydrogen production, hydrogen storage and green Mg-ion batteries. For hydrogen production, the role of intrinsic point defects to water adsorption on ZnO(10-10) surface is investigated. The findings show that the Zn and O defect-sites are energetically not favorable for the water adsorption and dissociation. For the purpose of storing hydrogen in a solid phase, silicene, doped by alkaline and alkaline earth metals, is investigated. We find that Li-doped and Na-doped silicene can attain the superior storage capacity. For cathode material of Mg-ion batteries, Mg2Mo6S8, the diffusivity of Mg ions occurs through an available channel in the bulk with the onset temperature of 200 K.

Ort, förlag, år, upplaga, sidor
Uppsala: Acta Universitatis Upsaliensis, 2015. s. 69
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1254
Nyckelord
Density functional theory, Pressure-induced phase transitions, Ab-initio molecular dynamic, hybrid functional, Ab-initio random structure searching, Phase change material
Nationell ämneskategori
Fysik
Forskningsämne
Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-251343 (URN)978-91-554-9247-2 (ISBN)
Disputation
2015-06-05, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2015-05-12 Skapad: 2015-04-15 Senast uppdaterad: 2015-07-07

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