Braunschweig, Techn. Universiẗat, Diss., 2004.

Hannover, Universiẗat, Diss., 2001.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 107-118).

Thesis (M.S.)--University of Michigan, 1973.

Thesis (M.D.)--University of Pennsylvania, 1808. Includes bibliographical references. / With a half-title. "An inaugural dissertation for the degree of doctor of medicine; submitted to the examination of John M'Dowell, L.L.D. provost, the trustees and medical professors of the University of Pennsylvania, on the twenty-seventh day of April, 1808."--p. [v]. Film 633 reel 6 is part of Research Publications Early American Medical Imprints collection (RP reel 6, no. 144). DNLM Includes bibliographical references.

We use rst-principles calculations based on density functional theory to study the structural properties and pressure-induced solid-solid phase transitions of ZnO. Both the local-density approximation (LDA) and the PBE96 form of the generalized gradi- ent approximation (GGA) are employed together with the projector augmented wave (PAW) method to mimic the electron-ion interaction. The electronic structure is investigated by the HSE hybrid functional and a partially self-consistent GWapprox- imation. We consider the wurtzite (B4), rocksalt (B1), zinc blende (B3), CsCl (B2), PbO (B10), NaTl (B32), WC (Bh), BN (Bk), NiAs (B81) and AsTi (Bi) modi cations of ZnO. The calculated structural properties in the B4, B3, B1 and B2 phases compare acceptably well with those found in previous theoretical studies, as is the transition pressure between them. We nd that the B4 phase is the most preferred low-pressure candidate in ZnO while the B2 phase is favorable at high pressures. Apart from the previously reported B4!B1!B2 phase transition, our study reveals other possible paths for a transition from B4 to B2 phase with the Bk, Bh, B10, and B81 structures as intermediate phases. It is found that the HSE and the GW approach o¤er a signif- icant improvement to the prediction of band-gaps in ZnO. The band-gaps are found to increase with increasing pressure leading to the structural phase transitions.

No description available.

Graduation date: 1978

No description available.

A half cell of an electrochromic (EC) device has been used to determine theelectrochromic response of a nickel oxide film in nine different electrolytes. Six of thenine electrolytes were 0.1 M non-aqueous salts dissolved in equal weight % ofpropylene carbonate and ethylene carbonate. Three of them were lithium-based andthree of them tetrabutylammonium (TBA)-based. The last three electrolytes wereproton-based aqueous solutions of 1 M KOH, 0.1 M propionic acid and 0.1 Mphosphoric acid, respectively. The electrolytes were subjected to electrochemical measurements of cyclicvoltammetry and square wave voltammetry, both with simultaneous in-situ opticaltransmittance measurements in the visible region. Ex-situ optical measurements wereperformed in the UV-VIS-NIR (300-2500 nm) range and IR-spectroscopymeasurements in the 600 – 4000 cm-1range.To determine the performance of the nickel oxide films, the coloration efficiency (CE)is used as a figure of merit. The desired value is to achieve a high optical modulationwith as little amount of charge inserted/extracted as possible.The results show that neither lithium nor TBA has a significant impact on theelectrochromic (EC) response, compared with the protonic electrolytes. Anargument can be made that the intercalation of neither cation (lithium or TBA) is thereason behind the electrochromic behaviour of the nickel oxide. In KOH it is ratherthe OH- that transfer to the surface and attracts protons (H+) from the bulk nickeloxide that enhances the EC response. In both propionic and phosphoric acid, it is thereversible intercalation of protons (H+) into the porous nickel oxide that gives theelectrochromic response.