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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.
1

Nanocarving of Titania Surfaces Using Hydrogen Bearing Gases

Rick, Helene Sylvia 18 May 2005 (has links)
An investigation of surface structures formed on polycrystalline and single crystal TiO2 (titania) samples having under gone various heat treatments in a controlled hydrogen bearing atmosphere was conducted. The study included the recreation and examination of the process discovered by Sehoon Yoo at Ohio State University to form nanofibers on the surface of polycrystalline TiO2 disks. Fibers were formed by heating samples to 700??in a 5%H2 95%N2 gas stream. The nanofibers formed during this processes are approximately 5-20 nanometers in diameter and can be 100??f nanometers long. The fibers do not actually grow on the surface, but are what remain of the surface as the material around them is removed by the gas stream V i.e., nanocarving. The mechanism of fiber formation and the effect of varying experimental parameters remained unknown and were explored within this study. This included changing gas composition, flow rate, and changes in sample preparation. The effect of isovalent doping and impurities within the starting powder were examined. Sintering temperature and time was investigated to determine the effect of grain size and surface morphologies prior to nanocarving. The effect of elevated temperature and 5%H2 95%N gas on the surface of TiO2 single-crystal wafers was also investigated. Test methods include Thermogravimetric Analysis (TGA), Mass Spectrometry (MS), Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) analysis.

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