Zhou Minjie = B₄C/FePt多層復合薄膜的製備與結構及物性研究 / 周民杰. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 55-57). / Text in English; abstracts in English and Chinese. / Zhou Minjie = B₄C/FePt duo ceng fu he bo mo de zhi bei yu jie gou ji wu xing yan jiu / Zhou Minjie. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgment --- p.iii / Table of contents --- p.iv / List of Figures --- p.vi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Background --- p.3 / Chapter 2.1 --- Structure and properties of boron carbide (B4C) --- p.3 / Chapter 2.2 --- Ultra-high-density magnetic recording --- p.4 / Chapter 2.3 --- Properties of FePt and previous experimental works in related fields --- p.7 / Chapter Chapter 3 --- Instrumentation --- p.9 / Chapter 3.1 --- Deposition system --- p.9 / Chapter 3.1.1 --- Ion beam sputtering --- p.9 / Chapter 3.1.2 --- Magnetron sputtering --- p.12 / Chapter 3.2 --- The chemical and structural characterization of the films --- p.13 / Chapter 3.2.1 --- X-ray Photoelectron Spectroscopy (XPS) --- p.13 / Chapter 3.2.2 --- X-ray Diffraction (XRD) --- p.15 / Chapter 3.2.3 --- Transmission Electron Microscope (TEM) --- p.16 / Chapter 3.3 --- The mechanical and magnetic properties of the films --- p.22 / Chapter 3.3.1 --- Nanoindentation and Stress measurement --- p.22 / Chapter 3.3.2 --- Vibrating sample magnetometer (VSM) --- p.23 / Chapter Chapter 4 --- Microstructure and hardness of pure B4C films by ion beam sputtering --- p.25 / Chapter 4.1 --- Fabrication and characterization of pure B4C thin films --- p.25 / Chapter 4.2 --- Discussions --- p.29 / Chapter Chapter 5 --- "Microstructure, magnetic and mechanical properties of B4C/FePt multilayer composite films by magnetron sputtering" --- p.32 / Chapter 5.1 --- Processing parameters optimization --- p.33 / Chapter 5.1.1 --- Optimization of annealing temperature --- p.33 / Chapter 5.1.2 --- Optimization of the Fe/Pt ratio --- p.37 / Chapter 5.2 --- Effect of B4C amount on the properties of the films --- p.40 / Chapter 5.3 --- Effect of the Fe-Pt deposition configuration on the film properties --- p.50 / Chapter Chapter 6 --- Summary --- p.53 / Reference --- p.55

Lee, Kin Hang = (La₀.₆₇Sr₀.₃₃MnO₃/La₀.₄₀Ca₀.₆₀MnO₃)多層薄膜的磁致電阻特性 / 李建恆. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / Lee, Kin Hang = (La₀.₆₇Sr₀.₃₃MnO₃/La₀.₄₀Ca₀.₆₀MnO₃) duo ceng bo mo de ci zhi dian zu te xing / Li Jianheng. / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Review of Magnetoresistance --- p.1 / Chapter 1.2 --- Giant magnetoresistance (GMR) --- p.4 / Chapter 1.3 --- Colossal magnetoresistance (CMR) and rare earth manganites --- p.6 / Chapter 1.3.1 --- Tolerance factor in perovskite structure --- p.8 / Chapter 1.3.2 --- Electronic structure and magnetic exchange mechanism --- p.10 / Chapter 1.3.3 --- Jahn-Teller (JT) distortion --- p.13 / Chapter 1.3.4 --- Magnetic and electronic phase diagram --- p.15 / Chapter 1.3.5 --- Charge ordering (CO) effect --- p.18 / Chapter 1.3.6 --- Percolation in a phase-separated state --- p.19 / Chapter 1.4 --- Phase separation at the interfaces in thin films --- p.24 / Chapter 1.5 --- Our motivation --- p.26 / Chapter 1.6 --- Review of manganite multilayer system --- p.27 / Chapter 1.7 --- Scope of this thesis --- p.34 / References --- p.35 / Chapter Chapter 2 --- Instrumentation / Chapter 2.1 --- Thin film deposition --- p.39 / Chapter 2.1.1 --- Facing target sputtering (FTS) --- p.40 / Chapter 2.1.2 --- Vacuum system --- p.43 / Chapter 2.2 --- Characterization --- p.45 / Chapter 2.2.1 --- α-step profilometer --- p.45 / Chapter 2.2.2 --- X-ray diffraction (XRD) --- p.45 / Chapter 2.2.3 --- Resistance measurement --- p.48 / Reference --- p.50 / Chapter Chapter 3 --- Epitaxial growth and characterization of single layer thin films / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Fabrication of the sputtering targets --- p.51 / Chapter 3.3 --- Epitaxial growth of single layer thin films --- p.52 / Chapter 3.3.1 --- Substrate materials --- p.52 / Chapter 3.3.2 --- Review of deposition conditions of our group with FTS system --- p.54 / Chapter 3.3.3 --- Substrate temperature --- p.57 / Chapter 3.3.4. --- Target-to-target distance and sputtering power --- p.58 / Chapter 3.3.5 --- Deposition procedures --- p.59 / Chapter 3.3 --- Characterization of single layer thin films --- p.60 / References --- p.64 / Chapter Chapter 4 --- La0.67Sr0.33MnO3/La0.40Ca0.60MnO3 multilayers / Chapter 4.1 --- Sample preparation --- p.65 / Chapter 4.2 --- As-grown multilayers --- p.69 / Chapter 4.2.1 --- Structural characterization of as-grown samples --- p.69 / Chapter 4.2.2 --- Transport properties of as-grown samples --- p.80 / Chapter 4.2.2.1 --- The effect of ts for fixed tc and the effect of tc for fixed ts --- p.83 / Chapter 4.2.2.2 --- The effect of thin La0.40Ca0.60MnO3 spacer layers --- p.92 / Chapter 4.2.2.3 --- The effect of fixed bilayer thickness --- p.94 / Chapter 4.2.2.4 --- The effect of ts for fixed volume fraction (tc / ts) --- p.97 / Chapter 4.2.2.5 --- The sample without M-I transition --- p.101 / Chapter 4.3 --- Discussion --- p.103 / References --- p.108 / Chapter Chapter 5 --- Conclusion --- p.110 / Chapter 5.1 --- Conclusion --- p.110 / Chapter 5.2 --- Future outlook --- p.112 / References --- p.114

Recent superconducting thin films studies have attempted to create pure metal layer films of Niobium and Titanium with the same properties of superconducting NbTi wire used in industry. These studies have all reported depression of the superconducting properties of the pure metal films which has been attributed to the proximity effect. The purpose of this research project was to construct several NbTi films composed of alloyed layers to overcome the proximity depression of superconducting properties. These films are unique in that they are the only films with both alloyed Nb/Ti superconducting and normal layers reported in the literature. Films with several different compositions and bilayer geometries were designed, constructed and their superconducting properties characterized. The films were created by the RF sputtering of alloyed targets at ambient temperatures. Characterization of the composition of the films was performed by microprobe analysis at two different electron beam voltages. A simulation of the electron beam excitation volume of the microprobe was performed to determine the difference in the two analyses and to determine whether the substrate would be found upon microprobe examination. X-ray diffraction was utilized to determine the bilayer spacing and to give a qualitative understanding of the alignment of the film microstructures. The critical temperature and upper critical magnetic field were measured to determine the superconducting properties and the extent of the proximity effect in the films. The microprobe analysis found most films to be very pure alloys except for films 6001, 6002, 6003(1) in which there were between 1-8 wt% of impurities. All films contained compositional variations on the order of 10 wt% from the design values. X-ray diffraction indicated agreement with the designed bilayer spacing in all films but 6003(2), 6005(1), and 6005(2) which had bilayer periods larger than originally designed. The proximity effect was not observed in any of the film's superconducting properties examined. T[subscript]c and H[subscript]c��� properties for the films without impurities had properties equal to that of bulk Nb/47wt% Ti. Films 6001, 6003(1) had depressed T[subscript]c and H[subscript]c��� values which were attributed to their impurity contamination. The low Ti composition in many of the films points to the inaccuracy of the deposition parameters when the films were first processed. The lack of T[subscript]c and H[subscript]c��� depression normally seen in other film studies with bilayer periods between 10-30 nm demonstrates that alloyed layers should be used to overcome the proximity effect in multilayer thin film superconductor studies. Overcoming the proximity effect should translate into a better understanding of flux pinning mechanisms in the material and increased superconducting critical currents in these films. / Graduation date: 1999

Graduation date: 1997

This study presents experimental works and finite element (FE) analyses for understanding nonlinear thermo-viscoelastic behaviors of multilayered (pultruded) composites under tension. Uniaxial isothermal creep tests in tension are conducted on Eglass/ Polyester pultruded composites of 0o, 45o and 90o off-axis fiber orientations subject to combined temperatures and stresses. The temperatures range from 0°F to 125°F, and stress levels range from 20% to 60% of the ultimate tensile strength of the composite specimen. The creep responses seem to accelerate with temperature for higher temperatures (75oF to 125oF) and do not behave in any particular manner for lower temperatures (0oF to 50oF). Isochronous curves of time-dependent material responses show that the nonlinearity increases with time and also temperature for higher temperatures while there is no particular trend seen at lower temperatures. Also, the creep responses of the axial specimens show negligible nonlinearity when compared to that of the transverse and 45o off-axis specimens. The Poisson’s effect is studied and orthotropic material symmetry conditions are satisfied. A nonlinear viscoelastic constitutive model, based on convolution integral equation, is presented for orthotropic materials. The nonlinear stress-temperature-dependent material parameters are coupled in the product form and are calibrated using the experimental data. Overall good predictions are shown but for a slight mismatch in the prediction of the responses at temperatures below 50 o F owing to the random behavior of the creep responses at lower temperatures. The numerical integration algorithm for the nonlinear viscoelastic model of orthotropic composite materials developed by Sawant and Muliana (2008) was used to integrate the constitutive material model to FE structural analyses. Sensitivity analysis is conducted to check for error in experiments by numerically simulating the testing procedure. A practical structural analysis is carried out on composite slabs using ABAQUS and our model is used to predict the responses of slabs under combined stress and temperature loading.

No description available.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed June 17, 2008). PDF text: vi, 94 p. : ill. (some col.) ; 3 Mb. UMI publication number: AAT 3293918. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Jan. 15, 2009). PDF text: 136 p. : ill. (chiefly col.) ; 3 Mb. UMI publication number: AAT 3315317. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves ). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 190 p.; also includes graphics. Includes bibliographical references (p. 181-190).