Sökning: "oxygen vacancy"

Visar resultat 16 - 20 av 35 avhandlingar innehållade orden oxygen vacancy.

1. 16. Hydrogen in oxides: a density-functional study of thermodynamic and kinetic aspects

   Författare :Mårten Björketun; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; proton conduction; La$_2$Zr$_2$O$_7$; protonation; kinetic Monte Carlo; density functional theory.; BaZrO$_3$; hydrogen oxide systems; electronic structure;

   Sammanfattning : Many solid oxides, especially those possessing a perovskite structure, exhibit significant proton conductivity when being acceptor doped and placed in hydrogen-containing atmospheres. Consequently, they have attracted attention foruse as solid membranes in electrochemical devices such as gas sensors, steam electrolyzers and fuel cells. LÄS MER

3. 17. Emerging mechanisms of FeCrAl(RE) oxide scale formation and permeation from 1st principles

   Författare :Vedad Babic; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Alumina forming alloys are important for high temperature applications due to the high stability of the alpha-Al2O3 scale which forms above 900 C. FeCrAl(RE) alloys are alumina formers with small additions of reactive elements, RE e.g. Y, Zr, Hf and Ce, added to improve among others oxidation behavior and scale adhesion. LÄS MER

4. 18. Ab initio studies of advanced functional materials with complex magnetism

   Författare :Duo Wang; Biplab Sanyal; Roland Mathieu; Claude Ederer; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Complex magnetism; 2D magnets; Functional material; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : For centuries, magnetism of materials has been an inevitable part of human civilization. Only in the last century, the mysteries of magnetism started to unfold thanks to the development of quantum theory of solids. LÄS MER

5. 19. Ionic Transport in Metal Oxides Studied in situ by Impedance Spectroscopy and Cyclic Voltammetry

   Författare :Johan Öijerholm; Jinshan Pan; Jürgen Fleig; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ionic transport; alumina; zirconia; in situ impedance spectroscopy; molecular dynamics; high temperature cyclic voltammetry; spark plasma sintering; initial oxidation; FeCrAl alloy; grain size; space charge model.; Electrochemistry; Elektrokemi;

   Sammanfattning : Ionic transport in metal oxides is crucial for the functioning of a broad range of different components, such as heat resistant alloys designed for high temperature applications and oxide electrolytes in solid oxide fuel cells. This thesis presents results from in situ electrochemical studies of properties related to ionic transport in metal oxides that are important for their applications as protective oxides and ionic conductors. LÄS MER

7. 20. Theoretical studies of lattice- and spin-polarons

   Författare :Nina Bondarenko; Olle Eriksson; Natalia Skorodumova; Manuel Pereiro; Maria Roser Valenti Vall; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Polaron; Nonlinear Schrödinger Equation; Nonlocality; Solitons; Integrable systems; Quantum field theory low energy ; Electron-phonon interaction; Density functional theory; Electronic structure of atoms and molecules; Spin-polaron; Langevin equation; Transport properties; Hubbard model; Heisenberg lattice; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Theoretical studies of lattice- and spin-polarons are presented in this thesis, where the primary tool is ab-initio electronic structure calculations. The studies are performed with employment of a variety of analytical and computational methods. LÄS MER