Matching Items (9)
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- All Subjects: Materials
- Creators: Chemical Engineering Program
- Creators: Department of Physics
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
Solid oxide fuel cells have become a promising candidate in the development of high-density clean energy sources for the rapidly increasing demands in energy and global sustainability. In order to understand more about solid oxide fuel cells, the important step is to understand how to model heterogeneous materials. Heterogeneous materials are abundant in nature and also created in various processes. The diverse properties exhibited by these materials result from their complex microstructures, which also make it hard to model the material. Microstructure modeling and reconstruction on a meso-scale level is needed in order to produce heterogeneous models without having to shave and image every slice of the physical material, which is a destructive and irreversible process. Yeong and Torquato [1] introduced a stochastic optimization technique that enables the generation of a model of the material with the use of correlation functions. Spatial correlation functions of each of the various phases within the heterogeneous structure are collected from a two-dimensional micrograph representing a slice of a solid oxide fuel cell through computational means. The assumption is that two-dimensional images contain key structural information representative of the associated full three-dimensional microstructure. The collected spatial correlation functions, a combination of one-point and two-point correlation functions are then outputted and are representative of the material. In the reconstruction process, the characteristic two-point correlation functions is then inputted through a series of computational modeling codes and software to generate a three-dimensional visual model that is statistically similar to that of the original two-dimensional micrograph. Furthermore, parameters of temperature cooling stages and number of pixel exchanges per temperature stage are utilized and altered accordingly to observe which parameters has a higher impact on the reconstruction results. Stochastic optimization techniques to produce three-dimensional visual models from two-dimensional micrographs are therefore a statistically reliable method to understanding heterogeneous materials.
ContributorsPhan, Richard Dylan (Author) / Jiao, Yang (Thesis director) / Ren, Yi (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Within recent years, metal-organic frameworks, or MOF’s, have gained a lot of attention in the materials research community. These micro-porous materials are constructed of a metal oxide core and organic linkers, and have a wide-variety of applications due to their extensive material characteristic possibilities. The focus of this study is the MOF-5 material, specifically its chemical stability in air. The MOF-5 material has a large pore size of 8 Å, and aperture sizes of 15 and 12 Å. The pore size, pore functionality, and physically stable structure makes MOF-5 a desirable material. MOF-5 holds applications in gas/liquid separation, catalysis, and gas storage. The main problem with the MOF-5 material, however, is its instability in atmospheric air. This inherent instability is due to the water in air binding to the zinc-oxide core, effectively changing the material and its structure. Because of this material weakness, the MOF-5 material is difficult to be utilized in industrial applications. Through the research efforts proposed by this study, the stability of the MOF-5 powder and membrane were studied. MOF-5 powder and a MOF-5 membrane were synthesized and characterized using XRD analysis. In an attempt to improve the stability of MOF-5 in air, methyl groups were added to the organic linker in order to hinder the interaction of water with the Zn4O core. This was done by replacing the terepthalic acid organic linker with 2,5-dimethyl terephthalic acid in the powder and membrane synthesis steps. The methyl-modified MOF-5 powder was found to be stable after several days of exposure to air while the MOF-5 powder exhibited significant crystalline change. The methyl-modified membrane was found to be unstable when synthesized using the same procedure as the MOF-5 membrane.
ContributorsAnderson, Anthony David (Author) / Lin, Jerry Y.S. (Thesis director) / Ibrahim, Amr (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Based on theoretical calculations, a material that is highly transmissive below 3000 nm and opaque above 3000 nm is desired to replace glass covers for flat plate solar thermal systems. Additionally, a suitable replacement material needs to have a sufficiently high operating temperature in order to prevent the glazing from melting and warping in a solar system. Traditional solar thermal applications use conventional soda lime glass or low iron content glass to accomplish this; however, this project aims to investigate acrylic, polycarbonate, and FEP film as suitable alternatives for conventional solar glazings. While UV-Vis and FT-IR spectroscopy indicate that these polymer substitutes may not be ideal when used alone, when used in combination with coatings and additives, these materials may present an opportunity for a glazing replacement. A model representing a flat plate solar collector was developed to qualitatively analyze the various materials and their performance. Using gathered spectroscopy data, the model was developed for a multi-glazing system and it was found that polymer substitutes could perform better in certain system configurations. To complete the model, the model must be verified using empirical data and coatings and additives investigated for the purposes of achieving the desired materials optical specifications.
ContributorsBessant, Justin Zachary (Author) / Friesen, Cody (Thesis director) / Lorzel, Heath (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Dry and steam NanoBonding™ are conceived and researched to bond Si-based surfaces, via nucleation and growth of a two-dimensional SiOxHy or hydrated SiOxHy interphase connecting surfaces at the nanoscale across macroscopic domains. The motivation is to create strong, long lasting, hermetically bonded sensors with their electronics for the development of an artificial pancreas and to bond solar cells to glass panels for robust photovoltaic technology. The first step in NanoBonding™ is to synthesize smooth surfaces with 20 nm wide atomic terraces via a precursor phase, ß-cSiO2 on Si(100) and oxygen-deficient SiOx on the silica using the Herbots-Atluri process and Entrepix’s spin etching. Smooth precursor phases act as geometric and chemical template to nucleate and grow macroscopic contacting domains where cross bridging occurs via arrays of molecular strands in the hydrated SiOxHy interphase. Steam pressurization is found to catalyze NanoBonding™ consistently, eliminating the need for direct mechanical compression that limits the size and shape of wafers to be bonded in turn, reducing the cost of processing. Total surface energy measurements via 3 Liquids Contact Angle Analysis (3L CAA) enables accurate quantitative analysis of the total surface energy and each of its components. 3L CAA at each step in the process shows that surface energy drops to 42.4 ± 0.6 mJ/m2 from 57.5 ± 1.4 mJ/m2 after the Herbots-Atluri clean of an “As Received” wafer. 3L CAA after steam pressurization Nanobonding™ shows almost complete elimination from 13.8 mJ/m2 ± 1.0 to 0.002 ±- 0.0002 mJ/m2 in the contribution of acceptors to the total free surface energy, and an increase from 0.2 ± .03 to 23.8± 1.6 mJ/m2 in the contribution of donors. This is consistent with an increase in hydroxylation of the ß-cSiO2 surface as a consistent precursor phase for cross-bridging. This research optimizes the use of glycerin, water, and α-bromo-naphtalene in the use of 3L CAA to effectively quantify the components of total free surface energy which helps to better understand the most consistent method for NanoBonding™.
ContributorsBennett-Kennett, Ross Buchanan (Author) / Culbertson, Robert (Thesis director) / Herbots, Nicole (Committee member) / Foy, Joseph (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor) / Department of Physics (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2013-05
Description
The problem of catastrophic damage purveys in any material application, and minimizing its occurrence is paramount for general health and safety. We have successfully synthesized, characterized, and applied dimeric 9-anthracene carboxylic acid (Di-AC)-based mechanophores particles to form stress sensing epoxy matrix composites. As Di-AC had never been previously applied as a mechanophore and thermosets are rarely studied in mechanochemistry, this created an alternative avenue for study in the field. Under an applied stress, the cyclooctane-rings in the Di-AC particles reverted back to their fluorescent anthracene form, which linearly enhanced the overall fluorescence of the composite in response to the applied strain. The fluorescent signal further allowed for stress sensing in the elastic region of the stress\u2014strain curve, which is considered to be a form of damage precursor detection. Overall, the incorporation of Di-AC to the epoxy matrix added much desired stress sensing and damage precursor detection capabilities with good retention of the material properties.
ContributorsWickham, Jason Alexander (Co-author) / Nofen, Elizabeth (Co-author, Committee member) / Koo, Bonsung (Co-author) / Chattopadhyay, Aditi (Co-author) / Dai, Lenore (Co-author, Thesis director) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Lithium ion batteries are quintessential components of modern life. They are used to power smart devices — phones, tablets, laptops, and are rapidly becoming major elements in the automotive industry. Demand projections for lithium are skyrocketing with production struggling to keep up pace. This drive is due mostly to the rapid adoption of electric vehicles; sales of electric vehicles in 2020 are more than double what they were only a year prior. With such staggering growth it is important to understand how lithium is sourced and what that means for the environment. Will production even be capable of meeting the demand as more industries make use of this valuable element? How will the environmental impact of lithium affect growth? This thesis attempts to answer these questions as the world looks to a decade of rapid growth for lithium ion batteries.
ContributorsMelton, John (Author) / Brian, Jennifer (Thesis director) / Karwat, Darshawn (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
In this project, we aim to fabricate PIN structure-like diodes for radiation detectors using Boron Nitride (BN). This fabrication is done by performing lithography and metal deposition processes on a Cubic Boron Nitride (cBN) of around 200 nm in thickness layer on top of a boron doped diamond substrate. The main goal is to create the most efficient and affordable alpha particle—and ideally neutron—detector in a radiation setting. Thus, making more accessible radiation detectors that can be more easily produced and disposed of, as well as minimizing the size of conventional detectors.
ContributorsGutierrez, Eric (Author) / Nemanich, Robert (Thesis director) / Zaniewski, Anna (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor)
Created2023-05
Description
Ionic liquids boast a wide variety of application as modern electrolytes. Their unique collection of attributes, most notably insignificant vapor pressures, considerable ionic conductivity, and excellent thermal stability, prove ionic liquids excellent candidates for low-temperature electrolyte applications. This project focuses on the development of a low-temperature iodide-based ionic liquid electrolyte for a molecular electronic transducer (MET) seismometer. Based on ionic liquid 1-butyl-3-methylimidazolium iodide ([BMIM][I]), a functional electrolyte system is developed and optimized with addition of organic solvents, gamma-butyrolactone (GBL) and propylene carbonate (PC), and lithium iodide, showing the promise of operating at excessively low temperatures. The molecular interactions between [BMIM][I] and the organic solvents were classified using FTIR and 1H NMR spectroscopy. Specifically, the presence of hydrogen bonding between the carbonyl group on the organic solvents and the [BMIM]+ cation were captured. The effect of these interactions on several electrolyte properties were observed, including an extended glass transition temperature (Tg) of -120.2 °C and enhanced transport properties. When compared to the previous formulations, the optimized electrolyte exhibits a broader working temperature range, a higher fluidity over the temperature range from 25°C to -75 °C, and an enhanced ionic conductivity at temperatures below -70 °C as suggested by the Vogel–Fulcher–Tammann (VFT) model. Cyclic voltammetry (CV) confirmed the electrochemical stability of the electrolyte as well as the activity of the I3- / I- redox reaction for the MET sensing technology at room temperature. The presented works not only present a facile strategy of designing low-temperature electrolyte systems via design of molecular interactions, but also support future operations of MET seismometer.
ContributorsMacdonald, Shaun Michael (Author) / Dai, Dr. Lenore L. (Thesis director) / Lin, Wendy (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
In this project we are analyzing the diamond-titanium interface as it applies to diamond-based diode devices, including alpha particle, proton, and neutron detectors. This is done through the fabrication of an O-terminated B-doped diamond sample with a 20 Å Ti / 10 Å Pt overlayer which was then annealed and examined via X-ray photoelectron spectroscopy (XPS). It was discovered that after annealing the sample at temperatures ranging from 400 C - 900 C that TiC was not formed at any point during this experiment. Possible reasons for this include a lack of sufficient titanium in order to form TiC and over oxygenating the diamond surface before the metal was deposited.
ContributorsJohnson, Holly (Author) / Zaniewski, Anna (Thesis director) / Nemanich, Robert (Committee member) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05