Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994. / Includes bibliographical references (leaves 79-81). / by Angela Sue Longo. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1992. / Includes bibliographical references (leaves 158-166). / by Nancy Frier Dean. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995. / Includes bibliographical references. / by Charles N. Pieczulewski. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, February 2011. / "February 2011." Cataloged from PDF version of thesis. / Includes bibliographical references (p. 76-81). / Porous anodic aluminum oxide, commonly known as AAO, has been widely used as a scaffold to synthesize nanowires and nanotubes. The porous alumina structure can be obtained from a simple electrochemical oxidation process, applying a positive voltage to an aluminum film placed in an electrolyte, and resulting in the formation of periodically arranged arrays of pores. It is possible to tune pore diameters and pore spacing by adjusting parameters such as the type of electrolyte, the pH, and the applied voltage. Once the barrier oxide is removed from the bottom of the pores, porous alumina that has been formed on conducting substrates can be used for growth of metal nanowires using electrodeposition. We synthesized Au and Pt nanowire arrays on Au or Pt substrates. During electrodeposition, Au nanowires that grew out of the pores developed a pyramidlike faceted shape. This was not observed for overgrown Pt nanowires. To understand this phenomenon, the microstructure and crystallographic characteristics of the overgrown Au and Pt nanowires were studied using SEM, TEM and XRD. It was found that the overgrown Au caps were single crystalline with (111) facets and textured along the [100] direction, while the Au nanowires in the pores were poly-crystalline with a [11 11] texture. Pt nanowires grown in pores were also polycrystalline and had a [111] texture, but the grain size was much smaller than that of the Au. In contrast with Au, no change of texture or microstructure was observed when Pt grew out of pores. The structure change observed for Au involves nucleation of a new crystal with a (100) texture. This is thought to be related to the changes in the overpotential that occur when the Au emerges from the pores. / by Yong Cheol Shin. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995. / Includes bibliographical references (leaf 18). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / by Patricio F. Mendez. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student submitted PDF version of thesis. / Includes bibliographical references (p. 130-147). / A central pillar of real-world engineering is controlled molding of different types of waves (such as optical and acoustic waves). The impact of these wave-molding devices is directly dependent on the level of wave control they enable. Recently, artificially structured metamaterials have emerged, offering unprecedented flexibility in manipulating waves. The design and fabrication of these metamaterials are keys to the next generation of real-world engineering. This thesis aims to integrate computer science, materials science, and physics to design novel metamaterials and functional devices for photonics and nanotechnology, and translate these advances into realworld applications. Parallel finite-difference time-domain (FDTD) and finite element analysis (FEA) programs are developed to investigate a wide range of problems, including optical micromanipulation of biological systems [1, 2], 2-pattern photonic crystals [3], integrated optical circuits on an optical chip [4], photonic quasicrystals with the most premier photonic properties to date [5], plasmonics [6], and structure-property correlation analysis [7], multiple-exposure interference lithography [8], and the world's first searchable database system for nanostructures [9]. / by Lin Jia. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 56-59). / High optical concentrations without excess heating in a stationary system can be achieved with a luminescent solar concentrator (LSC). Neodymium (Nd) and ytterbium (Yb) are excellent infrared LSC materials: inexpensive, abundant, efficient, and spectrally well-matched to high-performance silicon solar cells. These rare earth ions are reasonably transparent to their own radiation and capable of generating high optical concentrations. Neodymium's and ytterbium's disadvantage is their relatively poor absorption overlap with the visible spectrum. Transition metals such as chromium (Cr), titanium (Ti), and vanadium (V) have broadband absorption covering the visible and near-infrared and can efficiently sensitize neodymium and ytterbium through a non-radiative energy transfer process. Chromium, titanium, and vanadium containing glasses were fabricated using a custom designed glass making furnace. The optical properties including molar absorption coefficient, photoluminescence spectrum, and energy transfer characteristics were investigated to determine the suitability for LSC applications. Glasses containing Cr or V co-doped with Nd or Yb demonstrated energy transfer from the transition metal to the rare earth, a fundamental step toward integration into a LSC. Titanium co-doped glasses did not exhibit photoluminescence or energy transfer. Chromium co-doped glasses exhibit both forward and backward energy transfer. Vanadium holds the best promise as a sensitizer for LSC applications. / by Nicholas John Thompson. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2000. / Vita. / Includes bibliographical references (p. 200-201). / The transport of charged species in lithium ion batteries was studied from a microstructural point of view. Electron transport was analyzed using percolation theory and comparison with other conductor-insulator composites. An in situ filter pressing apparatus was designed and constructed in order to determine the percolation threshold in composite electrode systems. In addition, the effect of inter-particle interactions was qualitatively examined. The percolation threshold was determined to occur between 10 and 13 volume percent conductor loading for liquid electrolyte systems. In dissolved polymer systems, polymer adsorption shifted the percolation threshold to 25 volume percent. Ion transport was analyzed using a computer model designed by Doyle and Newman. Microstructural solutions to ameliorate the rate limiting steps were proposed and tested. Battery simulations demonstrated that the rate capability of lithium batteries could be improved both by utilizing plate-like particles aligned in parallel with the current flow, and also by producing a porosity gradient in the electrode. Using particles aligned parallel to the current flow allowed the elimination of tortuosity from the ion path. Graded electrodes provided superior ion transport near the electrode surface, where the ionic current is greatest, while additional capacity was available in the depth of the electrode, where ion transport was not as critical. / by Benjamin Hellweg. / S.M.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002. / Includes bibliographical references (p. 111-115). / The thermomechanical response of thin films/lines on thicker substrates under internal loadings resulting from material mismatch is examined. As the well-known Stoney formula is limited to isotropic, blanket films that undergo only small deformations, proper interpretation of curvature-stress relationships for new film geometries and for new experimental testing techniques requires an extension of this analytical framework. Mismatch stresses in thin films/lines and consequent curvature evolution of the film/line-substrate system are investigated in realistic, complex geometries relevant to industrial trends, such as high line aspect ratio, multi-level structure, and large diameter wafers. A combined analytical and numerical method is presented to evaluate curvature and stress evolution in metal and dielectric lines in an interconnect structure on a Si substrate during fabrication steps and subsequent thermal loading. An engineering map based on a closed-form solution for volume-averaged thermal stresses in lines is developed for material selection and design optimization. Coherent gradient sensing (CGS), an optical, full-field and vibration-insensitive experimental method, is used to study large deformation behavior of thin film-substrate systems by measuring the gradient of out-of-plane displacement of deformed surfaces. Experimental results are discussed in terms of the limitation of the small deformation theory upon which the Stoney formula is predicated. In particular, this work seeks to incorporate anisotropy and non-linearity arising from geometrical changes such as directional patterning and large deformation in the range of isotropic and linear-elastic material behavior. / by Tae-Soon Park. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007. / Includes bibliographical references (p. 137-147). / This thesis develops a machine learning framework for predicting crystal structure and applies it to binary metallic alloys. As computational materials science turns a promising eye towards design, routine encounters with chemistries and compositions lacking experimental information will demand a practical solution to structure prediction. We review the ingredients needed to solve this problem and focus on structure search. This thesis develops and argues for a search strategy utilizing a combination of machine learning and modern quantum mechanical methods. Structure correlations in a binary alloy database are extracted using probabilistic graphical models. Specific correlations are shown to reflect well-known structure stabilizing mechanisms. Two probabilistic models are investigated to represent correlation: an undirected graphical model known as a cumulant expansion, and a mixture model. The cumulant expansion is used to efficiently guide Density Functional Theory predictions of compounds in the Ag-Mg, Au-Zr, and Li-Pt alloy systems. Cross-validated predictions of compounds present in 1335 binary alloys are used to demonstrate predictive ability over a wide range of chemistries - providing both efficiency and confidence to the search problem. Inconsistencies present in the cumulant expansion are analyzed, and a formal correction is developed. Finally, a probabilistic mixture model is investigated as a means to represent correlation in a compact way. The mixture model leads to a significant reduction in model complexity while maintaining a level of prediction performance comparable to the cumulant expansion. Further analysis of the mixture model is performed in the context of classification. Unsupervised learning of alloy classes or groups is shown to reflect clear chemical trends. / by Christopher Carl Fischer. / Ph.D.