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The possibility of creating inorganic/organic hybrid materials has yet to be fully explored within geopolymer research. Using PDMS as an organic precursor, the surface of sodium and potassium geopolymers of varying precursor composition were functionalized with degraded PDMS oligomers. Both types of geopolymer yielded hydrophobic materials with BET surface

The possibility of creating inorganic/organic hybrid materials has yet to be fully explored within geopolymer research. Using PDMS as an organic precursor, the surface of sodium and potassium geopolymers of varying precursor composition were functionalized with degraded PDMS oligomers. Both types of geopolymer yielded hydrophobic materials with BET surface area of 0.6475 m2/g and 4.342 m2/g for sodium and potassium geopolymer, respectively. Each respective material also had an oil capacity of 74.75 ± 4.06 weight% and 134.19 ± 4.89 weight%. X-ray diffraction analysis demonstrated that the PDMS functionalized sodium geopolymers had similar crystal structures that matched references for zeolite A and sodalite. The potassium geopolymers were amorphous, but showed consistency in diffraction patterns across different compositions.
ContributorsMaurer, Matthew (Author) / Seo, Don (Thesis director) / Ciota, David (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2022-05
Description
Transition metal dichalcogenides (TMDs) are a family of layered crystals with the chemical formula MX2 (M = W, Nb, Mo, Ta and X = S, Se, Te). These TMDs exhibit many fascinating optical and electronic properties making them strong candidates for high-end electronics, optoelectronic application, and spintronics. The layered structure

Transition metal dichalcogenides (TMDs) are a family of layered crystals with the chemical formula MX2 (M = W, Nb, Mo, Ta and X = S, Se, Te). These TMDs exhibit many fascinating optical and electronic properties making them strong candidates for high-end electronics, optoelectronic application, and spintronics. The layered structure of TMDs allows the crystal to be mechanically exfoliated to a monolayer limit, where bulk-scale properties no longer apply and quantum effects arise, including an indirect-to-direct bandgap transition. Controllably tuning the electronic properties of TMDs like WSe2 is therefore a highly attractive prospect achieved by substitutionally doping the metal atoms to enable n- and p-type doping at various concentrations, which can ultimately lead to more effective electronic devices due to increased charge carriers, faster transmission times and possibly new electronic and optical properties to be probed. WSe2 is expected to exhibit the largest spin splitting size and spin-orbit coupling, which leads to exciting potential applications in spintronics over its similar TMD counterparts, which can be controlled through electrical doping. Unfortunately, the well-established doping technique of ion implantation is unable to preserve the crystal quality leading to a major roadblock for the electronics applications of tungsten diselenide. Synthesizing WSe2 via chemical vapor transport (CVT) and flux method have been previously established, but controllable p-type (niobium) doping WSe2 in low concentrations ranges (<1 at %) by CVT methods requires further experimentation and study. This work studies the chemical vapor transport synthesis of doped-TMD W1-xNbxSe2 through characterization techniques of X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectroscopy techniques. In this work, it is observed that excess selenium transport does not enhance the controllability of niobium doping in WSe2, and that tellurium tetrachloride (TeCl4) transport has several barriers in successfully incorporating niobium into WSe2.
ContributorsRuddick, Hayley (Author) / Tongay, Sefaattin (Thesis director) / Jiao, Yang (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor)
Created2024-05
Description

The United States healthcare system does not perform as well as other countries including Germany and England, despite spending the most money on healthcare. It is well-established that there have been attempts at reform in the U.S. healthcare system multiple times in the past. This research paper describes the health

The United States healthcare system does not perform as well as other countries including Germany and England, despite spending the most money on healthcare. It is well-established that there have been attempts at reform in the U.S. healthcare system multiple times in the past. This research paper describes the health care systems in the U.S., Germany, and England to analyze the strengths to create practical healthcare reform ideas for the U.S. This was done by describing each of the country's health care systems in detail, including the history of each country's health care system, the quality of care, the access to care, and the funding of the health care system. Based on this analysis of these health care systems, recommendations for health care reform are provided for the U.S. with revisions to the Affordable Care Act.

ContributorsEppinger, Jamie Marie (Author) / Don, Rachael (Thesis director) / Kizer, Elizabeth (Committee member) / College of Health Solutions (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Perovskite films are the future of solar cell technology as they are not only low cost to produce and lightweight but also have a 26% conversion efficiency. This is extremely close to the standard silicon solar cell. The key challenge limiting the commercialization potential of these films is their fragility

Perovskite films are the future of solar cell technology as they are not only low cost to produce and lightweight but also have a 26% conversion efficiency. This is extremely close to the standard silicon solar cell. The key challenge limiting the commercialization potential of these films is their fragility and durability to outdoors conditions. This project investigates the mechanical and material properties of these perovskite materials in order to understand their future manufacturing capabilities. Through the use of a spin coater, blade coater, and a double cantilever beam testing set up, the fracture energy (or toughness), Gc, of Perovskite films is determined. Understanding the properties of these films can help manufacturers determine how to best make durable films that can be used in everyday energy generation. Furthermore, this study offers strategies to improve the fracture energy of these films by adding polymers and food-additive starches to the recipe. The findings collected in this project present a technique to study the mechanical properties of perovskite-based solar technology and films and further aid the technology to become commercially viable.
ContributorsBakshi, Kayshavi (Author) / Rolston, Nicholas (Thesis director) / Li, Muzhi (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2023-12
Description
The study of the mechanical behavior of nanocrystalline metals using microelectromechanical systems (MEMS) devices lies at the intersection of nanotechnology, mechanical engineering and material science. The extremely small grains that make up nanocrystalline metals lead to higher strength but lower ductility as compared to bulk metals. Effects of strain-rate dependence

The study of the mechanical behavior of nanocrystalline metals using microelectromechanical systems (MEMS) devices lies at the intersection of nanotechnology, mechanical engineering and material science. The extremely small grains that make up nanocrystalline metals lead to higher strength but lower ductility as compared to bulk metals. Effects of strain-rate dependence on the mechanical behavior of nanocrystalline metals are explored. Knowing the strain rate dependence of mechanical properties would enable optimization of material selection for different applications and lead to lighter structural components and enhanced sustainability.
ContributorsHall, Andrea Paulette (Author) / Rajagopalan, Jagannathan (Thesis director) / Liao, Yabin (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used

This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used to characterize the corrosion behavior of samples before and after SMAT. Electrochemical tests indicated an improved corrosion resistance after application of SMAT process. The observed improvements in corrosion properties are potentially due to microstructural changes in the material surface induced by SMAT which encouraged the formation of a passive oxide layer. Further testing and research are required to understand the corrosion related effects of cryogenic SMAT and initial-surface finish as the COVID-19 pandemic inhibited experimentation plans.
ContributorsDeorio, Jordan Anthony (Author) / Solanki, Kiran (Thesis director) / Rajagopalan, Jagannathan (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
With renewable energy on the rise, researchers have turned their funding and their focus towards new solar cell technologies, and perovskites are a major source of interest. This class of materials is particularly interesting due to their quick, simple synthesis as well as their physical and electrical superiority when compared

With renewable energy on the rise, researchers have turned their funding and their focus towards new solar cell technologies, and perovskites are a major source of interest. This class of materials is particularly interesting due to their quick, simple synthesis as well as their physical and electrical superiority when compared to current silicon-based solar cells. Through this thesis, we will explore the synthesis of various types of perovskites and their subsequent characterization, which includes optical microscopy, photoluminescence spectroscopy, Raman microscopy, and X-ray diffraction. Analyzing two different perovskites both before and after a two-week period of storage revealed that while synthesis is indeed experiment-friendly, these materials have a concerning lack of stability even in ideal conditions.
ContributorsBuzas, Benjamin Joseph (Author) / Tongay, Sefaattin (Thesis director) / Muhich, Christopher (Committee member) / Materials Science and Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Hyperspectral imaging is a novel technology which allows for the collection of reflectance spectra of a sample in-situ and at a distance. A rapidly developing technology, hyperspectral imaging has been of particular interest in the field of art characterization, authentication, and conservation as it avoids the pitfalls of traditional characterization

Hyperspectral imaging is a novel technology which allows for the collection of reflectance spectra of a sample in-situ and at a distance. A rapidly developing technology, hyperspectral imaging has been of particular interest in the field of art characterization, authentication, and conservation as it avoids the pitfalls of traditional characterization techniques and allows for the rapid and wide collection of data never before possible. It is hypothesized that by combining the power of hyperspectral imaging with machine learning, a new framework for the in-situ and automated characterization and authentication of artworks can be developed. This project, using the CMYK set of inks, began the preliminary development of such a framework. It was found that hyperspectral imaging and machine learning as a combination show significant potential as an avenue for art authentication, though further progress and research is needed to match the reliability of status quo techniques.
ContributorsChowdhury, Tanzil Aziz (Author) / Newman, Nathan (Thesis director) / Tongay, Sefaattin (Committee member) / School of Politics and Global Studies (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Widespread knowledge of fracture mechanics is mostly based on previous models that generalize crack growth in materials over several loading cycles. The objective of this project is to characterize crack growth that occurs in titanium alloys, specifically Grade 5 Ti-6Al-4V, at the sub-cycle scale, or within a single loading cycle.

Widespread knowledge of fracture mechanics is mostly based on previous models that generalize crack growth in materials over several loading cycles. The objective of this project is to characterize crack growth that occurs in titanium alloys, specifically Grade 5 Ti-6Al-4V, at the sub-cycle scale, or within a single loading cycle. Using scanning electron microscopy (SEM), imaging analysis is performed to observe crack behavior at ten loading steps throughout the loading and unloading paths. Analysis involves measuring the incremental crack growth and crack tip opening displacement (CTOD) of specimens at loading ratios of 0.1, 0.3, and 0.5. This report defines the relationship between crack growth and the stress intensity factor, K, of the specimens, as well as the relationship between the R-ratio and stress opening level. The crack closure phenomena and effect of microcracks are discussed as they influence the crack growth behavior. This method has previously been used to characterize crack growth in Al 7075-T6. The results for Ti-6Al-4V are compared to these previous findings in order to strengthen conclusions about crack growth behavior.
ContributorsNazareno, Alyssa Noelle (Author) / Liu, Yongming (Thesis director) / Jiao, Yang (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Titanium dioxide is an essential material under research for energy and environmental applications, chiefly through its photocatalytic properties. These properties allow it to be used for water-splitting, detoxification, and photovoltaics, in addition to its conventional uses in pigmentation and sunscreen. Titanium dioxide exists in several polymorphic structures, of

Titanium dioxide is an essential material under research for energy and environmental applications, chiefly through its photocatalytic properties. These properties allow it to be used for water-splitting, detoxification, and photovoltaics, in addition to its conventional uses in pigmentation and sunscreen. Titanium dioxide exists in several polymorphic structures, of which the most common are rutile and anatase. We focused on anatase for the purposes of this research, due to its promising results for hydrolysis.

Anatase exists often in its reduced form (TiO2-x), enabling it to perform redox reactions through the absorption and release of oxygen into/from the crystal lattice. These processes result in structural changes, induced by defects in the material, which can theoretically be observed using advanced characterization methods. In situ electron microscopy is one of such methods, and can provide a window into these structural changes. However, in order to interpret the structural evolution caused by defects in materials, it is often necessary and pertinent to use atomistic simulations to compare the experimental images with models.

In this thesis project, we modeled the defect structures in anatase, around oxygen vacancies and at surfaces, using molecular dynamics, benchmarked with density functional theory. Using a “reactive” forcefield designed for the simulation of interactions between anatase and water that can model and treat bonding through the use of bond orders, different vacancy structures were analyzed and simulated. To compare these theoretical, generated models with experimental data, the “multislice approach” to TEM image simulation was used. We investigated a series of different vacancy configurations and surfaces and generated fingerprints for comparison with TEM experiments. This comparison demonstrated a proof of concept for a technique suggesting the possibility for the identification of oxygen vacancy structures directly from TEM images. This research aims to improve our atomic-level understanding of oxide materials, by providing a methodology for the analysis of vacancy formation from very subtle phenomena in TEM images.
ContributorsShindel, Benjamin Noam (Author) / Crozier, Peter (Thesis director) / Anwar, Shahriar (Committee member) / Singh, Arunima (Committee member) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05