Sökning: "impurities"

Visar resultat 16 - 20 av 260 avhandlingar innehållade ordet impurities.

  1. 16. Electronic structure calculations on defects and impurities in semiconductors

    Författare :Hongqi Xu; Fasta tillståndets fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysicumarkivet A:1991:Xu;

    Sammanfattning : [abstract missing].... LÄS MER

  3. 17. The Impact of Hydrocarbon and Carbon Oxide Impuritiesin the Hydrogen Feed of a PEM Fuel Cell

    Författare :Katrin Kortsdottir; Rakel Wreland Lindström; Göran Lindbergh; Tanja Kallio; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fuel Cell; Hydrogen Impurities; Carbon Monoxide; Carbon Dioxide; Ethene; Propene; Methane; Propane; Toluene; Electrochemically Active Surface Area; Cyclic Voltammetry; Mass Spectrometry; bränslecell; vätgasföroreningar; kolmonoxid; koldioxid; eten; propen; metan; propan; toluen; elektrokemisk aktiv yta; cyklisk voltammetri; masspektrometri; Chemical Engineering; Kemiteknik;

    Sammanfattning : The proton exchange membrane fuel cell generates electricity from hydrogen and oxygen (from air) through electrocatalytic reactions in an electrochemical cell. The Pt/C catalyst, commonly used in PEM fuel cells, is very sensitive to impurities that can interact with the active catalyst sites and limit fuel cell performance. LÄS MER

  4. 18. GaN, AlGaN, GaNAs and Related Heterostructures Grown by Molecular Beam Epitaxy

    Författare :Hyonju Kim; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; surface segregation; GaNAs; plasma-assisted MBE; stacking fault; AlGaN GaN; heterointerface; unintentional impurities; III-nitrides;

    Sammanfattning : This work deals with growth and characterization of III-nitrides and related heterostructures as well as GaNAs alloys grown by plasma assisted molecular beam epitaxy (MBE). The III-nitrides belong to the wide bandgap semiconductors due to their large energy bandgap spanning from 1.9 to 6.2 eV. LÄS MER

  5. 19. Local structure and composition : in additively manufactured bulk metallic glasses and composites

    Författare :Inga Katharina Goetz; Jochen M. Schneider; Björgvin Hjörvarsson; Ulf Jansson; Maria Teresa Pérez Prado; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; additive manufacturing; bulk metallic glasses; nanoscale clustering; convective flow; laser nitriding; laser powder bed fusion; metallic glass - ceramic composites; oxygen impurities; mechanical properties; magnetic properties; viscosity; Fysik; Physics;

    Sammanfattning : Additive manufacturing enables the production of complex multi-material geometries and bulk metallic glass parts beyond their critical casting thickness. The local modification of structure, composition, and properties is explored in this thesis with the aim to design novel composite materials and functional gradients. LÄS MER

  7. 20. Electronic structure calculations of native defects and impurities in III-V semiconductors

    Författare :Andreas Höglund; Uppsala universitet; []
    Nyckelord :;

    Sammanfattning : .... LÄS MER