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Visar resultat 1 - 5 av 7 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Two Problems in non-linear PDE’s with Phase Transitions

    Författare :Karl Jonsson; Henrik Shahgholian; Tomas Sjödin; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Conductivity jump; Free boundary problem; Quasilinear elliptic equation; Mathematical techniques; Nonlinear analysis; Free boundary; Free-boundary problems; Quasi-linear elliptic; Quasilinear elliptic equations; Hele-Shaw flow; non-local; implicit function theorem; Heterogeneous Multi Scale; HMM; Finite Element; FEM; FE; Mathematics; Matematik;

    Sammanfattning : This thesis is in the field of non-linear partial differential equations (PDE), focusing on problems which show some type of phase-transition. A single phase Hele-Shaw flow models a Newtoninan fluid which is being injected in the space between two narrowly separated parallel planes. LÄS MER

  3. 2. Neutron spectroscopy and computational studies of hydride-ion dynamics in oxide- and nitride-hydride materials

    Författare :Lucas Fine; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Oxide-hydride; phonons; inelastic neutron scattering; hydride-ions; quasielastic neutron scattering; density functional theory.; nitride-hydride; diffusion;

    Sammanfattning : This thesis presents studies of the hydride-ion dynamics in the nitride- and oxide­hydride materials Ca3CrN3H and BaTiO3-xHx (with x < 0.2). LÄS MER

  4. 3. Intermediate Temperature Solid Ionic Conductors and Fuel Cells

    Författare :Zhu Bin; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; molten phase; bulk and interfacial conduction; intermediate temperature; salt-ceramic composites; solid state proton conductors and fuel cells; blocked and non-blocked mobile species; ionic and protonic conduction and diffusion; oxyacid salts;

    Sammanfattning : Novel solid proton conductors based on oxyacid salts and salt-ceramic composites and intermediate temperature fuel cells have been developed in this thesis work. The discovery of proton conduction in these materials introduces a new concept of proton conductors and starts a new research field - Intermediate Temperature Solid Proton Conductors and Fuel Cells. LÄS MER

  5. 4. 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

  7. 5. Dynamical properties of metal halide and oxyhydride perovskites

    Författare :Rasmus Lavén; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; perovskite; quasielastic neutron scattering; phonon; inelastic neutron scattering; diffusion; oxyhydride; hydrogen dynamics; Metal halide perovskite; hydride ion.;

    Sammanfattning : This thesis concerns investigations on the dynamical properties of two classes of energy-relevant materials, namely metal halide and oxyhydride perovskites, using neutron scattering techniques. These two classes of materials share the same aspect of a perovskite-type crystal structure but are different in terms of their functional properties and concomitant promise for various technological applications. LÄS MER