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Visar resultat 1 - 5 av 8 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Alumina Thin Films : From Computer Calculations to Cutting Tools

   Författare :Erik Wallin; Ulf Helmersson; Patrick Desjardins; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Alumina; thin films; coatings; sputtering; density functional theory; high power impulse magnetron sputtering; HIPIMS; Material physics with surface physics; Materialfysik med ytfysik; Surface engineering; Ytbehandlingsteknik; Surfaces and interfaces; Ytor och mellanytor;

   Sammanfattning : The work presented in this thesis deals with experimental and theoretical studies related to alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. LÄS MER

3. 2. X-ray Absorption Spectroscopy on Nano-Magnet Arrays and Thin Films : Magnetism and Structure

   Författare :Andreas Persson; Dimitri Arvanitis; Cormac McGuinness; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; self organization; nano-magnet; xmcd; exafs; peem; magnetism; Surfaces and interfaces; Ytor och mellanytor; Magnetism; Magnetism; Materiefysik; Physics of Matter;

   Sammanfattning : The magnetic and structural properties of nano magnet arrays and ferromagnetic thin films are investigated. Circular x-rays are used and extensive use is made in this Thesis of the X-ray Magnetic Circular Dichroism (XMCD) technique. By means of the XMCD magneto-optic sum rules the values of the orbital and spin moments are determined. LÄS MER

4. 3. Surface studies on α–sapphire for potential use in GaN epitaxial growth

   Författare :Björn Agnarsson; Mats Göthelid; Anders Sandell; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Surfaces and interfaces; Ytor och mellanytor;

   Sammanfattning : This Licentiate thesis summarizes the work carried out by the author the years 2004 to 2008 at the University of Iceland and the Royal Institute of Technology (KTH) in Sweden. The aim of the project was to investigate the structure of sapphire (alpha-Al2O3) surfaces, both for pure scientific reasons and also for potential use as substrate for GaN-growth by molecular beam epitaxy. LÄS MER

5. 4. Insights into Materials Properties from Ab Initio Theory : Diffusion, Adsorption, Catalysis & Structure

   Författare :Andreas Blomqvist; Rajeev Ahuja; Christopher Wolverton; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Molecular dynamics; Diffusion; Catalysis; Adsorption; Random structure search; Hydrogen-storage materials; Phase-change materials; Defects and diffusion; Defekter och diffusion; Surfaces and interfaces; Ytor och mellanytor; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : In this thesis, density functional theory (DFT) calculations and DFT based ab initio molecular dynamics simulations have been employed in order to gain insights into materials properties like diffusion, adsorption, catalysis, and structure. In transition metals, absorbed hydrogen atoms self-trap due to localization of metal d-electrons. LÄS MER

7. 5. Influence of Self-trapping, Clamping and Confinement on Hydrogen Absorption

   Författare :Gunnar Karl Pálsson; Björgvin Hjörvarsson; Keith Ross; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hydrogen diffusion; thin films; superlattices; phase transitions; confinement; clamping; self-trapping; finite-size effect; Surfaces and interfaces; Ytor och mellanytor; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : The dissociation of hydrogen molecules at surfaces is the first step in the absorption process. If the absorbing material is covered by an oxide, this layer will determine the effective uptake rate of an underlying absorbing material. LÄS MER