Sökning: "Rietveld refinements"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Rietveld refinements.

  1. 1. Proton Conducting Ceramics; Synthesis, Characterization and Sample Cell Environments

    Författare :FRANCIS GACHAO KINYANJUI; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; perovskites; neutron diffraction; Rietveld refinements; BaSnO3; in-situ cell; deuteron position; proton conduction; BaZrO3;

    Sammanfattning : Acceptor doped Perovskite ceramics have been shown to exhibit high levels of protonic conduction in humid atmospheres. However significant grain boundary resistance and long sintering times required to achieve sufficient grain size growth has hindered their widespread application as electrolyzers, fuel cells and gas separation membranes. LÄS MER

  2. 2. Functional Oxide Materials exhibiting Ionic Conductivity for Future Energy Conversion Needs

    Författare :FRANCIS GACHAO KINYANJUI; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; neutron diffraction; perovskites; oxygen deficient perovskites; BaSnO3; Rietveld refinements; BaZrO3; in-situ cells; proton conduction; deuteron position; Ba3In2ZrO8;

    Sammanfattning : Fuel cells are electrochemical devices that transform the chemical energy in hydrogen and oxygen into electrical energy at high efficiencies and produce only water vapour emissions. Materials with the perovskite or fluorite structure types are commonly employed as the ion conducting ceramic electrolyte membranes in intermediate and high temperature fuel cells. LÄS MER

  3. 3. Synthesis, Structure and Proton Conduction of Substituted BaTiO3 and BaZrO3 Perovskites

    Författare :Seikh Mohammad Habibur Rahman; Chalmers University of Technology; []
    Nyckelord :deuteron position; Rietveld refinements; heavily doped oxygen deficient perovskite BaTiO3 BaZrO3 ; neutron total scattering; New proton conductor; X-ray and neutron powder diffraction; RMC modelling.; Impedance spectroscopy;

    Sammanfattning : Proton conducting oxides can be beneficial as electrolyte materials in devices such as fuel cells, hydrogen sensors etc. Proton conducting fuel cells (PCFCs), utilising H2 as fuel, stand out as a promising technology for future clean energy generation. LÄS MER

  4. 4. Preparation, structure and properties of Hg, Tl-containing high-temperature superconductors

    Författare :Martin Valldor; Stephen Berger; Springfield College/Manchester; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; oorganisk kemi; Inorganic Chemistry;

    Sammanfattning : Powder samples with the general composition (Tl,Hg)2(Ba,Sr)2(Sr,Ca)Cu2O8-d, abbreviated 2212, were synthesised by solid-state reaction of metal oxides in closed silica ampoules. Depending on the relative amounts of Ba, Sr, and Ca, the superconducting transition temperature, Tc, varied significantly (45-100 K). LÄS MER

  5. 5. In-situ phase studies of the Zr-H system

    Författare :Tuerdi Maimaitiyili; Malmö högskola; []
    Nyckelord :Zirconium hydride; synchrotron X-ray diffraction; neutron diffraction; phase transformation; in-situ hydrogen charging; hydrogen related degradation; in situ phase transformation; hydrogen embrittlement; hydrogen charging; zirconium hydride; γ-ZrH; hydrogen induced degradation;

    Sammanfattning : Zirconium alloys are widely used in the nuclear industry because of their high strength, good corrosion resistance and low neutron absorption cross-section. However, zirconium has strong affinity for hydrogen, which may lead to hydrogen concentration build-up over time during a corrosion reaction when exposed to water. LÄS MER