LD2668 .T4 1966 C434 / Master of Science

Dissertation made openly available per email from author, 6/13/2016.

The performance of multilayer thin film optical filters depends largely on the microstructure of the component layers. This microstructure varies with the deposition parameters inside the coating chamber. By controlling these parameters, optical filters can be produced to exacting specifications. In 1947, R. M. Rice established the technique of bombarding the substrate with electrons of several kilovolts as the fils were being deposited. This process improved the durability of zinc sulfide films dramatically. This study was performed to quantitatively analyze the effects of bombardment on film microstructure and subsequent effects on optical and mechanical properties. I installed an electron source filament inside the coating chamber and electrically isolated the substrate holder, which was connected to a positive high voltage supply. An accelerating loop placed just above the filament enhanced its efficiency. The source was calibrated by measuring the current through the substrate holder. Single layer films of five different materials were deposited, each at its own set of electron bombardment parameters. The microstructure was analyzed with an X-ray diffractometer and a transmission electron microscope. Optical properties were measured with guided waves, induced absorption, and spectrophotometric analysis. Film durability was analyzed with scotch tape, eraser, and controlled humidity tests. Antimony trioxide films showed a shift in lattice orientation, but this did not affect columnar structure or macroscopic quantities. Potassium hexafluorozirconate films showed elimination of both crystal structure and columnar growth, resulting in slightly reduced durability and some absorption. Silicon monoxide films suffered no change in structure or properties. Zinc sulfide films demonstrated the change in crystal structure, which was quantified and shown to improve moisture resistance. Optical properties were unaffected. Magnesium fluoride films showed a slight increase in crystallinity with only subtle changes in durability and optical properties. Generally, electron bombardment reduced or rearranged crystal structure. The effects on macroscopic properties varied with each material, with no clear trend evident.

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När en kock komponerar en maträtt som skall fotograferas kommer han behöva göra en medveten estetisk bedömning innan maträtten tillagas, för att sedan analysera och förstå hur betraktaren uppfattar matfotografi. I denna litteraturstudie är syftet att undersöka hur estetiska begrepp och bildanalysmetoder tillämpas inom matfotografi. Uppsatsen bygger på en litteraturstudie, där fyra vetenskapliga artiklar har tillämpats för att besvara syftet. Resultatet i litteraturstudien visar att det är svårt att finna en metod att applicera på matfotografi, men om det går att skapa ett språk med flera metoder tillsammans finns det stora fördelar ur ett analytiskt perspektiv. Tillämpningen av estetiska begrepp tillsammans med bildanalyser är komplicerat och forskningen som gjorts är inte tillräcklig / B-uppsatser

by Chung Pui Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 105-110). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of contents --- p.v / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Metal clusters embedded in fused silica glass --- p.2 / Chapter 1.2 --- Ion implantation of metal clusters --- p.3 / Chapter 1.3 --- Feature of MEVVA implantation --- p.5 / Chapter 1.4 --- Motivation and organization of this thesis --- p.7 / Chapter Chapter 2. --- Sample Preparation and Characterization Methods / Chapter 2.1 --- MEVVA implantation --- p.9 / Chapter 2.2 --- TRIM simulation --- p.11 / Chapter 2.3 --- Sample preparation --- p.14 / Chapter 2.4 --- Rutherford backscattering spectroscopy (RBS) --- p.16 / Chapter 2.5 --- X-ray diffraction (XRD) technique --- p.17 / Chapter 2.6 --- X-ray photoelectron spectroscopy (XPS) --- p.21 / Chapter 2.7 --- Transmission electron microscopy (TEM) technique --- p.24 / Chapter 2.8 --- Spectroscopic ellipsometry (S.E.) --- p.25 / Chapter 2.9 --- Z-scan technique --- p.32 / Chapter Chapter 3. --- Characterization of Single Implanted Samples / Chapter 3.1 --- Experimental results and discussion / Chapter 3.1.1 --- RBS --- p.35 / Chapter 3.1.2 --- XRD --- p.38 / Chapter 3.1.3 --- XPS --- p.42 / Chapter 3.1.4 --- XTEM --- p.49 / Chapter 3.1.5 --- S.E --- p.54 / Chapter 3.1.6 --- Z-scan measurements --- p.60 / Chapter 3.2 --- Summary --- p.65 / Chapter Chapter 4. --- Characterization of Sequentially Cu-Ni Implanted Samples / Chapter 4.1 --- Experimental results and discussion / Chapter 4.1.1 --- XRD --- p.66 / Chapter 4.1.2 --- XPS --- p.68 / Chapter 4.1.3 --- XTEM --- p.77 / Chapter 4.1.4 --- Z-scan measurements --- p.87 / Chapter 4.2 --- Summary --- p.91 / Chapter Chapter 5. --- Conclusion and Future Works / Chapter 5.1 --- Conclusion --- p.92 / Chapter 5.2 --- Future works --- p.93 / Appendix / Appendix I --- p.94 / Chapter ☆ --- Sample preparation procedures for XTEM / Appendix II --- p.97 / Chapter ☆ --- Alignment procedures of S.E. / Chapter ☆ --- Implementation of the Merlin system / Appendix III --- p.101 / Chapter ☆ --- Calibration of S.E. / Reference --- p.105

Yeung Chun Fai = 厚度和眞空熱處理對單晶 La0.67Ca0.33MnO3 薄膜特性之影響 / 楊進輝. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Yeung Chun Fai = Hou du he zhen kong re chu li dui dan jing La0.67Ca0.33MnO3 bo mo te xing zhi ying xiang / Yang Jinhui. / Acknowledgements --- p.i / Abstract --- p.ii / 論文摘要 --- p.iv / Table of contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xiii / Chapter Chapter I --- Introduction / Chapter 1.1 --- Development of magnetoresistance materials --- p.1-1 / Chapter 1.1.1 --- Magnetoresistance (MR) --- p.1-1 / Chapter 1.1.2 --- Anisotropy magnetoresistance (AMR) --- p.1-1 / Chapter 1.1.3 --- Giant magnetoresistance (GMR) --- p.1-2 / Chapter 1.1.4 --- Colossal magnetoresistance (CMR) in rare-earth manganites --- p.1-3 / Chapter 1.1.5 --- Possible origin of CMR in rare-earth manganites --- p.1-4 / Chapter 1.1.5.1 --- Double exchange mechanism --- p.1-4 / Chapter 1.1.5.2 --- Jahn-teller effect --- p.1-6 / Chapter 1.1.5.3 --- Other mechanisms --- p.1-7 / Chapter 1.1.6 --- Possible origins of CMR in Thallium manganite pyrochlores (TI2Mn207) --- p.1-7 / Chapter 1.2 --- New developments in manganite materials --- p.1-8 / Chapter 1.3 --- Our approach --- p.1-8 / Chapter 1.3.1 --- Why choose La0 .67Ca0.33Mn03 material? --- p.1-8 / Chapter 1.3.2 --- The role of oxygen content in manganite materials --- p.1-9 / Chapter 1.4 --- The scope of this thesis work --- p.1-11 / References --- p.1-12 / Chapter Chapter II --- Instrumentation / Chapter 2.1 --- Thin film deposition --- p.2-1 / Chapter 2.1.1 --- Introduction --- p.2-1 / Chapter 2.1.2 --- Facing-target sputtering (FTS) --- p.2-3 / Chapter 2.1.3 --- Deposition profile calculation for sputtering with FTS --- p.2-4 / Chapter 2.1.4 --- Vacuum system --- p.2-7 / Chapter 2.2 --- Characterization --- p.2-8 / Chapter 2.2.1 --- Profilometer --- p.2-8 / Chapter 2.2.2 --- Atomic force microscopy (AFM) --- p.2-8 / Chapter 2.2.3 --- X-ray diffraction (XRD) --- p.2-8 / Chapter 2.2.4 --- Resistance and magnetoresistance measurement --- p.2-10 / Chapter 2.2.5 --- Hall effect measurement --- p.2-11 / References --- p.2-13 / Chapter Chapter III --- Epitaxial growth of La0.67Ca0.33 Mn03 thin films / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- Fabrication and characteristics of LCMO target --- p.3-1 / Chapter 3.3 --- Substrate materials --- p.3-5 / Chapter 3.4 --- Deposition --- p.3-10 / Chapter 3.4.1 --- Sample preparation --- p.3-10 / Chapter 3.4.2 --- Substrate temperature --- p.3-10 / Chapter 3.4.3 --- Deposition process --- p.3-17 / Chapter 3.5 --- Post-annealing effect --- p.3-18 / Chapter 3.6 --- Film composition analysis --- p.3-22 / Chapter 3.7 --- Epitaxial growth examination --- p.3-22 / References --- p.3-27 / Chapter Chapter IV --- Thickness effect in single-crystal LCMO thin films grown on NGO and STO / Chapter 4.1 --- Motivation --- p.4-1 / Chapter 4.2 --- Resistance measurement --- p.4-2 / Chapter 4.3 --- Magnetoresistance (MR) --- p.4-8 / Chapter 4.4 --- Crystal structure --- p.4-12 / Chapter 4.5 --- Surface morphology --- p.4-16 / Chapter 4.6 --- Hall effect measurement --- p.4-19 / Chapter 4.6.1 --- Basic principle --- p.4-19 / Chapter 4.6.2 --- Experiment --- p.4-20 / Chapter 4.6.3 --- Carrier concentration & mobility --- p.4-20 / Chapter 4.7 --- Discussions --- p.4-25 / References --- p.4-27 / Chapter Chapter V --- Strain dependent vacuum annealing effectin single-crystal La0.67Ga0.33MnO3 thin films / Chapter 5.1 --- Motivation --- p.5-1 / Chapter 5.2 --- Sample description --- p.5-1 / Chapter 5.3 --- Vacuum annealing process --- p.5-2 / Chapter 5.4 --- Crystal structure --- p.5-2 / Chapter 5.5 --- Resistance measurement --- p.5-6 / Chapter 5.6 --- Discussions --- p.5-8 / Chapter 5.6.1 --- Lattice expansion --- p.5-8 / Chapter 5.6.2 --- Determination of oxygen content --- p.5-9 / References --- p.5-11 / Chapter Chapter VI --- Activation energy of small polaron in La0.67Ca0.33MnO3 thin films / Chapter 6.1 --- Motivation --- p.6-1 / Chapter 6.2 --- Basic theory --- p.6-1 / Chapter 6.2.1 --- Variable range hopping --- p.6-1 / Chapter 6.2.2 --- Semiconduction --- p.6-2 / Chapter 6.2.3 --- Nearest-neighbor hoping of small polarons --- p.6-2 / Chapter 6.3 --- Sample description --- p.6-3 / Chapter 6.4 --- Resistance measurement --- p.6-4 / Chapter 6.5 --- Activation energy --- p.6-4 / Chapter 6.6 --- Discussions --- p.6-5 / References --- p.6-12 / Chapter Chapter VII --- Conclusions --- p.7-1

One of the key elements to the success of Pd-Ag membrane based reactor for the H2 production is the synthesis of thin and highly selective membranes using the electroless plating method. This work describes the effect of electroless plating conditions on the obtained Pd and Ag deposits properties (morphology, compactness, phase structure, compositional homogeneity and adhesion) important from synthesis of thin and H2 selective membrane viewpoint. Both sequential and co-deposition deposition methods were investigated. The conventional Pd and Ag plating conditions (NH3+EDTA based bath) produced dendritic and non-uniform sequential (multi layer) deposits, not suitable for synthesizing the thin and H2 selective Pd-Ag membranes. Ag under the conventional plating conditions deposited at high overpotential resulting in the dendritic and non-uniform sequential deposits. The modified Ag plating conditions eliminated Ag deposition at high overpotential and the sequential deposits obtained were non-dendritic and uniform. Thin (< 10 µm thick) and H2 selective Pd-Ag membranes were successfully synthesized using the modified Ag plating conditions. The membranes were then successfully annealed at 550 oC. After the annealing step, the membranes showed activation energy for the H2 permeation (4.3-11.5 kJ/mole) lower than that of the pure Pd membrane (12-16.4 kJ/mole) meaning that the Pd-Ag membranes were more effective for the H2 separation at lower temperatures than the pure Pd membrane. A Pd-Ag (20 wt%) membrane showed H2 permeance higher by a factor of 2.47 at 250 oC than the pure Pd foil. The Pd-Ag membranes also showed decline in the H2/He selectivity on exposure to the annealing and H2 permeation (300-500 oC) study conditions. The Pd-Ag co-deposits obtained (using NH3+EDTA bath) were dendritic, inhomogeneous with poor substrate adhesion, therefore not suitable for the membrane synthesis. The co-deposits were bi-metallic and required the annealing step to form the Pd-Ag alloy. There existed a large difference in the deposition potentials (600 to 650 mV) of Pd and Ag. The Ag deposition was severely controlled by its mass transfer in the solution resulting in the dendritic and inhomogeneous deposits. Among the different complexing agents investigated, KCl showed the least difference between the Pd and Ag deposition potentials. The co-deposits obtained using the KCl bath were non-dendritic, homogeneous and were Pd-Ag alloy therefore required no annealing step. Finally, the multi step plating, annealing and polishing approach was used to avoid the decline in the selectivity of the sequentially prepared Pd-Ag membranes. The membranes prepared by the plating, annealing and polishing approach showed very high selectivity (H2/He) and no decline in the selectivity was observed between 300-450 oC for the total exposure time > 550 h (> 200 h at 450 oC).

by Chen Dihu. / "November 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 160-173). / 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.

Bibliography: leaves 210-223.