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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Nonlinearity of the MOS tunneling structure 1-V characteristic for submillimeter radiation detection.

Fish, Lawrence Irwin. January 1972 (has links)
No description available.
72

Environmental electrochemistry of organic compounds at metal oxide electrodes

Makgae, Mosidi Elizabeth 12 1900 (has links)
Dissertation (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This study investigates the electrochemical oxidation of phenol. Phenol is a major toxin and water pollutant. In addition, during water treatment it reacts with chlorine to produce carcinogenic chlorophenols. lts treatment down to trace levels is therefore of increasing concern. For this purpose, dynamically stable anodes for the breakdown of phenols to carbon dioxide or other less harmful substances were developed and characterized. The anodes were prepared from mixed oxides of tin (Sn) and the precious metals ruthenium (Ru), tantalum (Ta) and iridium (Ir), which in tum were prepared using sol-gel techniques. This involved dip-coating the aqueous salts of the respective metals onto titanium substrates and heating to temperatures of several hundreds of degree Celsius. The properties of these mixed oxide thin films were investigated and characterized using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), elemental dispersive energy X-ray analysis (EDX), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), particle induced X-ray emission (PIXE) and electrochemical measurements. A variety of different electrode materials including Til Sn02-Ru02-Ir02, Ti/Ta20s-Ir02 and Ti/RhOx-Ir02 were developed and tested for their potential as oxidation catalysts for organic pollutants in wastewaters. Depending on the anode type, phenol was found to be electrochemically degraded, to different extents, on these surfaces during electrolysis. It was however found that the oxidation rate not only depended on the chemical composition but also on the oxide morphology revealed, resulting from the preparation procedure. The Ti/SnOz-Ru02-Ir02 film was found to be the most efficient surface for the electrolytic breakdown of phenol. This film oxidized phenol at a potential of 200 mV vs Ag/AgC!. The activity of the catalytic systems was evaluated both on the basis of phenol removal efficiency as well as the kinetics of these reactions. Phenol removal efficiency was more than 90% for all the film surfaces prepared and the rate of the reaction followed first order kinetics. A pathway for the electrochemical degradation of phenol was derived using techniques such as HPLC to identify the breakdown products. These pathway products included the formation of benzoquinone and the further oxidation of benzoquinone to the carboxylic acids malic, malonic and oxalic. / AFRIKAANSE OPSOMMING: Die onderwerp van hierdie studie is die elektrochemiese oksidasie van fenol deur nuwe gemengde-oksied elektrodes. Fenol is 'n belangrike gifstof en besoedelingsmiddel in water. Daarbenewens kan fenolook met chloor reageer tydens waterbehandeling om sodoende karsinogeniese chlorofenole te vorm. Dit is dus belangrik dat metodes ondersoek word wat die konsentrasie van fenol in water verminder. Hierdie studie behels die bereiding en karakterisering van nuwe dinamiese stabiele anodes (DSA) vir die afbreek van fenol tot koolstofdioksied en ander minder gevaarlike verbindings. Hierdie nuwe anodes is berei vanaf die gemengde-okside van die edelmetale tin (Sn), ruthenium (Ru), tantalum (Ta) en iridium (Ir), met behulp van sol-gel tegnieke. Die finale stap in die bereiding behels kalsinering van die oksides by temperature van "n paar honderd grade Celsius. Hierdie nuwe elektrodes is later gebruik om die oksidasie van fenol te evalueer. Die gemengde-oksied dunlae/anodes IS d.m.v. die volgende analitiesetegnieke gekarakteriseer: termiese-gravimetriese analise (TGA), skandeerelektronmikroskopie (SEM), atoomkragmikroskopie (AFM), elementverstrooiingsenergie- X-straalanalise (EDX), X-straaldiffraksie (XRD), Rutherford terug-verstrooiingspektroskopie (RBS), partikel-geinduseerde X-straal emissie (PIXE), en elektrochemiese metings. 'n Verskeidenheid elektrodes van verskillende materiale is berei en hul potensiaal as oksidasie-kataliste vir organiese besoedelingsmiddels in afloopwater bepaal. Hierdie elektrodes het die volgende ingesluit: Ti/Sn02-Ru02-Ir02, Ti/Ta20s-Ir02 en Ti/RhOx-Ir02. Gedurende elektrolise is fenol elektrochemies afgebreek tot verskillende vlakke, afhangende van die tipe elektrode. Die oksidasietempo het egter nie alleen van die chemiese samestelling van die elektrode afgehang nie, maar ook van die morfologie van die okside, wat op hulle beurt van die voorbereidingsprosedure afgehang het. Daar is bevind dat die Ti/Sn02-Ru02-Ir02 elektrode die mees effektiewe oppervlakke vir die afbreek van fenol is. Hier het die oksidasie van fenol by 'n potensiaal van 200 mV plaasgevind. Die aktiwiteite van die katalitiese sisteme IS bepaal op grond van hulle fenolverwyderingsdoeltreffendheid. Die kinetika van die reaksies is ook bepaal. Al die elektrodes het >90% fenolverwyderingsdoeltreffendheid getoon en die reaksietempos was van die eerste-orde. Deur van analitiese tegnieke soos hoëdrukvloeistofchromatografie (HPLC) gebruik te maak is die afbreekprodukte van fenol geïdentifiseer en 'n skema vir die elektrochemiese afbreek van fenol uitgewerk. Daar is bevind dat bensokinoon gevorm het, wat later oksidasie ondergaan het om karboksielsure te vorm.
73

Sol-gel preparation, characterisation and electrochemistry of mixed metal tin oxide electrodes

Baker, Priscilla G. L. 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming
74

Effect of morphologies and electronic properties of metal oxide nanostructure layer on dye sensitized solar cells

Yip, Cho-tung., 葉佐東. January 2010 (has links)
published_or_final_version / Physics / Doctoral / Doctor of Philosophy
75

Tuning metal oxides for solar cells and light emitting diodes

Hoye, Robert Lianqi Zhao January 2015 (has links)
No description available.
76

Investigating defect states and charge transport in amorphous metal oxides for thin-film transistor applications

Socratous, Josephine January 2015 (has links)
No description available.
77

The synthesis and characterization of phosphonic acids for the surface modification study on indium tin oxide

Feng, Guanhua 09 May 2012 (has links)
The synthesis and characterization of some phosphonic acids as well as the modification of indium tin oxide (ITO) substrates using these phosphonic acids are presented in this thesis. Phosphonic acids have been known to bind strongly to the surface of a number of metal oxides. ITO substrates were reported to be modified with a variety of surface modifiers. Herein the ITO substrates were modified with the chosen phosphonic acids with different functional groups in order to tune the work function and compare the work function changes with the functional group properties.
78

Use of photosensitive metal-organic precursors to deposit metal-oxides for thin-film capacitor applications

Barstow, Sean J., January 2003 (has links) (PDF)
Thesis (Ph. D.)--School of Chemical Engineering, Georgia Institute of Technology, 2004. Directed by Clifford L. Henderson. / Includes bibliographical references (leaves 366-371).
79

Microcalorimetric heats of adsorption, surface residence times and sticking probabilities of metals on metal-oxide, and silicon substrates /

Starr, David E. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 159-165).
80

Transmission electron microscopy study of growth of oxide film in nanoparticles of Cr and Fe /

Chan, Chun Man. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 58-59). Also available in electronic version. Access restricted to campus users.

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