Sökning: "defect cluster"

Visar resultat 1 - 5 av 20 avhandlingar innehållade orden defect cluster.

1. 1. Point defects and ion conduction in solid oxides: a first-principles case study of La2Zr2O7

   Författare :Joakim Nyman; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; proton; self compensation; hydrogen economy; DFT; La2Zr2O7; acceptor doping; lanthanum zirconate; oxygen vacancy; SOFC; pyrochlore; point defect; trapping; computational methods; solid oxide; charge compensation; first principles; ion conduction; solid oxide fuel cell; ceramic electrolyte; defect cluster; fuel cell; hydrogen;

   Sammanfattning : In the endeavor to attain a clean environment and sustainable energy consumption, the notion of a future hydrogen economy stands out as one of the grandest visions. Striving for this vision, a critical task lies in optimizing the performance of the fuel-cell devices responsible for extracting electric power from the energy stored in hydrogen molecules. LÄS MER

3. 2. Combined Molecular Dynamics and Embedded-Cluster Calculations in Metal Oxide Surface Chemistry

   Författare :Björn Herschend; Kersti Hermansson; Micael Baudin; Joachim Sauer; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Inorganic chemistry; embedded-cluster; ab initio; molecular dynamics; metal oxide; ceria; magnesium oxide; adsorption; surface defect; Oorganisk kemi; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : The development and improvement of the functionality of metal oxides in heterogeneous catalysis and other surface chemical processes can greatly benefit from an atomic-level understanding of the surface chemistry. Atomistic calculations such as quantum mechanical (QM) calculations and molecular dynamics (MD) simulations can provide highly detailed information about the atomic and electronic structure, and constitute valuable complements to experimental surface science techniques. LÄS MER

4. 3. First principles study of tungsten-based alloys: From defect thermodynamics to phase diagrams

   Författare :Leili Gharaee; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; structural materials; first-principles calculations.; point defects; tungsten alloys; irradiation;

   Sammanfattning : Nuclear fusion is a very attractive option for energy production as it is clean, safe and efficient. The major obstacle in construction of fusion power plants is the development of materials that can tolerate the extreme operational condition especially high-energy neutron flux. LÄS MER

5. 4. Optimizing nontarget workflows for identification of organic contaminants in various matrices

   Författare :Florian Dubocq; Anna Kärrman; Thanh Wang; Juliane Hollender; Örebro universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nontarget analysis; workflow optimization; statistical analysis; mass defect plot; organic contaminants; environmental matrices;

   Sammanfattning : Since year 2000, production of chemicals around the world has more than doubled. Chemicals are used in many and diverse applications in our everyday life and even if their properties are useful, some can have a negative impact on environment and humans. LÄS MER

7. 5. Modelling of radiation damage and positron annihilation in metallic materials

   Författare :Qigui Yang; Pär Olsson; Bernardo Barbiellini; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Radiation damage; First-principles; Positron annihilation spectroscopy; Cu precipitation; Two-component density functional theory; Tungsten; Transition metals; Kärnenergiteknik; Nuclear Engineering; Physics; Fysik;

   Sammanfattning : The radiation damage is one of the key concerns in the research of materials used in radiation environments. In this thesis, we theoretically investigate the radiation damage phenomenon by focusing on two important topics: the defect production and evolution, and the defect characterization. The first part aims at two aspects. LÄS MER