Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Vivek B. Shenoy. Includes bibliographical references (leaves 191-200). Also available online.

published_or_final_version / Physics / Master / Master of Philosophy

"May 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Leang Po Shan = 利用飛行時間散射反衝符號測量譜儀研究LiTaO3(001)單晶之表面電荷動態特性 / 梁寶珊. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 50-51). / Text in English; abstracts in English and Chinese. / Leang Po Shan = Li yong fei xing shi jian san she fan chong fu hao ce liang pu yi yan jiu LiTaO3(001) dan jing zhi biao mian dian he dong tai te xing / Liang Baoshan. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Ferroelectricity and pyroelectricity of LiTαO3 --- p.1 / Chapter 1.2 --- Surface Studies of Ferroelectrics --- p.5 / Chapter 1.2.1 --- Size Effect and Importantce of Surface Properties --- p.5 / Chapter 1.2.2 --- General Difficulties in Surface Studies of Ferroelectrics --- p.5 / Chapter 1.2.3 --- Applicability of TOF-SARS in the Analysis of Ferro- electrics --- p.6 / Chapter 1.3 --- Surface Charge Dynamics on Ferroelectrics --- p.7 / Chapter 1.3.1 --- Surface Charge Screening of Spontaneous Polarization --- p.7 / Chapter 1.3.2 --- Discharge of Excessive Surface Charge --- p.7 / Chapter 1.4 --- Objectives of the Thesis Work: TOF-SARS Study of Surface Charge Dynamics of LiTαO3 --- p.11 / Chapter 2 --- Ion-Surface Interaction --- p.13 / Chapter 3 --- Time-of-Flight (TOF) Ion Scattering and Recoiling Spectrom- eter --- p.17 / Chapter 3.1 --- TOF Ion Scattering and Recoiling Spectrometer --- p.18 / Chapter 3.2 --- Ion Column --- p.19 / Chapter 3.2.1 --- Ion Source --- p.19 / Chapter 3.2.2 --- Pulsing System --- p.19 / Chapter 3.2.3 --- ExB Wien Filter Mass Analyzer --- p.20 / Chapter 3.2.4 --- Einzel Lens --- p.20 / Chapter 3.2.5 --- Neutral Beam Trap --- p.20 / Chapter 3.2.6 --- Vacuum Chamber and Manipulator --- p.20 / Chapter 3.3 --- Variable Angle Detector --- p.23 / Chapter 3.3.1 --- Setup --- p.23 / Chapter 3.3.2 --- Beam Alignment --- p.24 / Chapter 4 --- Results and Analysis --- p.25 / Chapter 5 --- Study of Charge Relaxation Process --- p.35 / Chapter 5.1 --- Derivation of Surface Electric Potential --- p.35 / Chapter 5.2 --- Data Analysis --- p.40 / Chapter 6 --- Conclusion --- p.49 / Bibliography --- p.50

A liquid crystal (LC) at its boundary surface adopts a preferential alignment, which is referred to as anchoring. The direction of this alignment (i.e., anchoring direction) may be perpendicular, parallel or tilted with respect to the surface. Transitions from one anchoring condition to another may occur when the parameters (e.g., temperature) charactering the surface change, as referred to as anchoring transitions. In the LC-polymer composite systems under our study, the anchoring and temperature- driven anchoring transitions of nematic fluids is very sensitive to the structure of the side chain of poly (alkyl acrylate) matrixes that encapsulate the LC. We have shown that the anchoring transition temperature of these systems can be tuned far below the nematic-to-isotropic transition temperature, by varying either the length, branching structure of the side chains of homopolymers, or the composition of copolymer of two dissimilar monomers. Both sharp and broad anchoring transitions with respect to the temperature range over which a transition occurs were observed. It is postulated that microscopic interactions between the polymer side chains and LC molecules play an important role in determining the anchoring. In particular, the conformation of the polymer side chain is proposed to have important control over the anchoring. Anchoring strength and tilt angle as a function of temperature during the anchoring transitions were also experimentally investigated, which contribute to understanding of the microscopic mechanism for such transitions. Based on the LC-polymer composites with controlled anchoring, a LC display with reverse switching mode and a novel electrically switchable diffraction grating have been demonstrated. The advantages of these devices are ease of manufacturing, low operation voltage, and mechanical stability offered by polymer matrix. Moreover, a detailed study of the director configuration of wall defects found in these composite films was carried out using fluorescence confocal polarized microscopy.

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.