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The stable rock salt like ThO chemically synthesized under pressure by theory
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The rock salt like ThO was predicted to be stable under pressure by ab initio method. The procedure is applying pressure to the following reaction: Th+ThO2=) ThO. ThO is energetically favored in a range of 14 GPa - 26 GPa by the proof of reaction enthalpy. The lattice dynamic of ThO shows its stability under high pressure. In this reaction, Thorium metal plays signicant role on the reaction by the contributing of the transformation s, d to f orbital occupation. It is found that the lled f electrons mainly are at expense of s electrons. The newly stabilized ThO is metallic. The stabilizer is the hybridization of d - p electrons. The concentration of oxygen bonded to Th induce crystal eld splitting in d and f bands. The lled f electrons do inuence the energy level of d bands. We also found that ThO2 has a indirect band gap at 20 GPa.

National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-120059OAI: oai:DiVA.org:kth-120059DiVA: diva2:613297
Funder
Swedish Research Council
Note

QS 2013

Available from: 2013-03-27 Created: 2013-03-27 Last updated: 2013-03-27Bibliographically approved
In thesis
1. Heavy Metal Compounds and Hydrogen Storage Materials from Ab Initio Calculations
Open this publication in new window or tab >>Heavy Metal Compounds and Hydrogen Storage Materials from Ab Initio Calculations
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. vii, 32 p.
National Category
Materials Engineering
Identifiers
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 (English)
Opponent
Supervisors
Note

QC 20130327

Available from: 2013-03-27 Created: 2013-03-27 Last updated: 2013-03-27Bibliographically approved

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