Sökning: "point defect"

Visar resultat 1 - 5 av 93 avhandlingar innehållade orden point defect.

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. Point defect interactions and structural stability of compounds

   Författare :Vitaly Baykov; Börje Johansson; Peter Mohn; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; first principles; ab initio; density functional theory; point defects interactions; diluted magnetic semiconductors; structural stability; zirconium alloys; Other materials science; Övrig teknisk materialvetenskap;

   Sammanfattning : Theoretical studies of point defect interactions and structural stability of compounds have been performed using density functional theory. The defect-related properties, such as activation energy of diffusion, electronic and magnetic structure of selected materials have been studied. LÄS MER

4. 3. Exact Results in Supersymmetric Field Theories : A dissertation on the defect and deformed

   Författare :Erik Widen; Konstantin Zarembo; Nikolay Gromov; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AdS CFT correspondence; integrability; localization; supersymmetric deformations; Quantum Spectral Curve; defect CFT; one-point functions; Theoretical Physics; Teoretisk fysik;

   Sammanfattning : Quantum field theories (QFTs) are the most precise descriptions of the physical reality that humanity has found. Yet exact predictions are often missing as most computations are notoriously difficult to carry out. One generally resorts to perturbation theory which immediately limits the regime of validity. LÄS MER

5. 4. On hydrogen point defects in perovskite oxides

   Författare :Erik Jedvik Granhed; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; density functional theory; oxyhydride; phonon; point defects; chemical expansion; polaron; BaZrO3; proton conductor; BaTiO3;

   Sammanfattning : Oxides based on the perovskite structure exhibit a surprisingly large diversity in materials properties and are found in many different applications, several related to clean energy technologies, such as solar cells, batteries and fuel cells. Many properties in materials are the result of lattice imperfections, commonly denoted \emph{defects}, and much effort is devoted to fine tuning materials properties through controlling the defects therein. LÄS MER

7. 5. Electronic Structure Calculations of Point Defects in Semiconductors

   Författare :Andreas Höglund; Susanne Mirbt; Alison Mainwood; Uppsala universitet; []
   Nyckelord :Physics; electronic structure calculations; point defects; semiconductor; formation energy; equilibrium solubility limit; thermodynamic equilibrium concentration; transfer levels; negative-U; 110 surface; diffusion; activation energy; solar cells; Fysik;

   Sammanfattning : In this thesis point defects in semiconductors are studied by electronic structure calculations. Results are presented for the stability and equilibrium concentrations of native defects in GaP, InP, InAs, and InSb, for the entire range of doping conditions and stoichiometry. LÄS MER