Matching Items (75)

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Synthesis and Electrochemical Characterization of Silicon Clathrates for Use in Lithium-Ion Battery Anodes

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Lithium-ion batteries are one of the most widely used energy storage solutions today. As renewable energy sources proliferate to meet growth in worldwide energy consumption, it is important that lithium-ion

Lithium-ion batteries are one of the most widely used energy storage solutions today. As renewable energy sources proliferate to meet growth in worldwide energy consumption, it is important that lithium-ion batteries be improved to help capture this energy for use when the demand arises. One way to boost the performance of lithium-ion batteries is to replace the electrode active materials with materials of higher specific capacity. Silicon is one material that has been widely touted as a potential replacement for the graphite used in commercial anodes with a theoretical capacity of 3500 mAh/g as opposed to graphite's 372 mAh/g. However, bulk silicon is known to pulverize after experiencing large strains during lithiation. Here, silicon clathrates are investigated as a potential structure for accommodation of these strains. Silicon clathrates consist of covalently bonded silicon host cages surrounding a guest alkali or alkaline earth metal ion. Previous work has looked at silicon clathrates for their superconducting and thermoelectric properties. In this study, electrochemical properties of type I and II silicon clathrates with sodium guest ions (NaxSi46 and NaxSi136) and type I silicon clathrates with copper framework substitution and barium guest ions (Ba8CuxSi46-x) are examined. Sodium clathrates showed very high capacities during initial lithiation (>2500 mAh/g), but rapidly lost capacity thereafter. X-ray diffraction after lithiation showed conversion of the clathrate phase to lithium silicide and then to amorphous silicon after delithiation, indicating destruction of the clathrate structure as a possible explanation for the rapid capacity fade. Ba8CuxSi46-x clathrates were found to have their structures completely intact after 50 cycles. However, they had very low reversible capacities (<100 mAh/g) and potentially might not be electrochemically active. Further work is needed to better understand exactly how lithium is inserted into clathrates and if copper impurities detected during wavelength-dispersive X-ray spectroscopy could be inhibiting lithium transport into the clathrates.

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  • 2014-05

Bio-Inspired Cementation of Soil Using Plant Enzyme

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This dissertation investigates the potential for enzyme induced carbonate cementation as an alternative to Portland cement for creating building material from sand aggregate. We create a solution of urease enzyme,

This dissertation investigates the potential for enzyme induced carbonate cementation as an alternative to Portland cement for creating building material from sand aggregate. We create a solution of urease enzyme, calcium chloride (CaCl2), and urea in water and added sand. The urease catalyzes the synthesis of carbonate from urea, and the carbonate then bonds with a dissociated calcium ion and precipitates from the solution as calcium carbonate (CaCO3). This precipitate can form small crystal bridges at contacts between sand grains that lock the sand grains in place. Using enzyme induced carbonate precipitation we created a cemented sand sample with a maximum compressive strength of 319 kPa and an elastic modulus of approximately 10 MPa. Images from the SEM showed that a major failure mechanism in the cemented samples was the delamination of the CaCO3 from the sand grains. We observed that CaCO3 cementation did not when solutions with high concentrations of CaCl2 and urea were used.

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  • 2014-05

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Novel Applications to Si Heterojunction Solar Cells

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Proposed and tested were three different methods to deposit important layers of Silicon heterojunction solar cells (SHJs). If there were a shortage of Silver, Aluminum could be substituted for the

Proposed and tested were three different methods to deposit important layers of Silicon heterojunction solar cells (SHJs). If there were a shortage of Silver, Aluminum could be substituted for the contacts. If there were a shortage of Indium, Yttrium Zinc Oxide could be substituted. To improve the solar cell, the p and n type layers can be grown with hydrogenated nanocrystallline Silicon (nc-Si:H). 40% and 50% nc-Si:H has shown a maximum absorbance reduction of 5 times compared to hydrogenated amorphous Silicon (a-Si). The substitutions offer alternatives which increase the total possible amount of solar cell production, advancing toward completion of the Terrawatt challenge.

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  • 2014-05

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Effect of Defects on Calculation of Electron Energy Loss Spectra of Ceria and Titania

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Climate change is one of the biggest challenges facing today's society.Since the late 19th century, the global average temperature has been rising. In order to minimize the temperature increase of

Climate change is one of the biggest challenges facing today's society.Since the late 19th century, the global average temperature has been rising. In order to minimize the temperature increase of the earth, it is necessary to develop alternative energy technologies that do not depend on fossil fuels. Solar fuels are one potential energy source for the future. Solar fuel technologies use catalysts to convert low energy molecules into fuels via artificial photosynthesis. TiO2, or titania, is an important model photocatalyst for studying these reactions. It is also important to use remaining fossil fuel resources efficiently and with the lowest possible greenhouse gas emissions. Fuel cells are electrochemical devices that aim to accomplish this goal and CeO2, or ceria, is an important material used in these devices. One way to observe the atomic structure of a material is with a transmission electron microscope (TEM). A traditional transmission electron microscope employs a beam of fast electrons to form atomic resolution images of a material. While imaging gives information about the positions of the atoms in the material, spectroscopy gives information about the composition and bonding of the material. A type of spectroscopy that can be performed inside the transmission electron microscope is electron energy loss spectroscopy (EELS), which provides a fundamental understanding of the electronic structure of a material. The energy loss spectrum also contains information on the chemical bonding in the material, and theoretical calculations that model the spectra are essential to correctly interpreting this bonding information. FEFF is a software that performs EELS calculations. Calculations of the oxygen K edges of TiO2 and CeO2 were made using FEFF in order to understand the changes that occur in the spectrum when oxygen vacancies are introduced as well as the changes near a grain boundary.

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  • 2013-12

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Commentary and Critique on Lesson Plans Utilizing 3D Printing Technology in K-12 Education.

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Analysis of 4 lesson plans for primary education in which 3D printers are used either to build components or are directly used by students. Provides critique on how proper investment

Analysis of 4 lesson plans for primary education in which 3D printers are used either to build components or are directly used by students. Provides critique on how proper investment and utilization of this new technology can enrich education and misuse can waste time, money, and even reduce the quality of education.

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  • 2014-05

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Market Research for Titanium Rifle Barrel

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There is a growing market for lightweight firearm barrels. Currently this market is dominated by Aluminum and Carbon fiber barrels, however, Gunwright, LLC proposes an innovative new way to manufacture

There is a growing market for lightweight firearm barrels. Currently this market is dominated by Aluminum and Carbon fiber barrels, however, Gunwright, LLC proposes an innovative new way to manufacture Titanium firearm barrels. This report offers insight into potential customers and existing competitors.

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  • 2014-05

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Under the Camper Shell

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The objective for Under the Camper Shell was to build a prototype of a full living environment within the confines of a pickup truck bed and camper shell. The total

The objective for Under the Camper Shell was to build a prototype of a full living environment within the confines of a pickup truck bed and camper shell. The total volume available to work with is approximately 85ft3. This full living environment entails functioning systems for essential modern living, providing shelter and spaces for cooking, sleeping, eating, and sanitation. The project proved to be very challenging from the start. First, the livable space is extremely small, being only tall enough for one to sit up straight. The truck and camper shell were both borrowed items, so no modifications were allowed for either, e.g. drilling holes for mounting. The idea was to create a system that could be easily removed, transforming it from a camper to a utility truck. The systems developed for the living environment would be modular and transformative so to accommodate for different necessities when packing. The goal was to create a low-water system with sustainability in mind. Insulating the space was the largest challenge and the most rewarding, using body heat to warm the space and insulate from the elements. Comfort systems were made of high density foam cushions in sections to allow folding and stacking for different functions (sleeping, lounging, and sitting). Sanitation is necessary for healthy living and regular human function. A composting toilet was used for the design, lending to low-water usage and is sustainable over time. Saw dust would be necessary for its function, but upon composting, the unit will generate sufficient amounts of heat to act as a space heater. Showering serves the functions of exfoliation and ridding of bacteria, both of which bath wipes can accomplish, limiting massive volumes of water storage and waste. Storage systems were also designed for modularity. Hooks were installed the length of the bed for hanging or securing items as necessary. Some are available for hanging bags. A cabinetry rail also runs the length of the bed to allow movement of hard storage to accommodate different scenarios. The cooking method is called "sous-vide", a method of cooking food in air-tight bags submerged in hot water. The water is reusable for cooking and no dishes are necessary for serving. Overall, the prototype fulfilled its function as a full living environment with few improvements necessary for future use.

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  • 2014-12

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INTEL ATOM'S TRANSITION TO THE MOBILE DEVICES CPU MARKET

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The semiconductor industry looks to constantly improve the efficiency of research and development in order to reduce costs and time to market. One such method was designed in order to

The semiconductor industry looks to constantly improve the efficiency of research and development in order to reduce costs and time to market. One such method was designed in order to decrease time spent inducing warpage in integrated circuits in an Intel research process. Intel's Atom product line seeks to compete with ARM architecture by entering the mobile devices CPU market. Due to the fundamental differences between the Atom's Bonnell architecture and the ARM architecture, the Intel Atom product line must utilize such improved research and development methods. Until power consumption is drastically lowered while maintaining processing speed, the Atom product line will not be able to effectively break into the mobile devices CPU market.

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  • 2013-05

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Wet NanoBonding™: Catalyzing Molecular Cross-Bridges and Interphases Between Nanoscopically Smoothed Si-Based Surfaces and Tailoring Surface Energy Components

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

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™.

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  • 2013-05

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Ensuring Success in an Industrial Internship: And my personal account of working for Intel

Description

The characteristics possessed by undergraduates who have enjoyed success in an intern position are defined. Through an interview process, four traits were identified: multitasking, strong team work understanding, an inquisitive

The characteristics possessed by undergraduates who have enjoyed success in an intern position are defined. Through an interview process, four traits were identified: multitasking, strong team work understanding, an inquisitive nature, and application of a cross-disciplinary mindset. An exposition of how these four traits are employed to ensure success in an internship setting is then given. Finally, a personal account of a project with Intel is expounded upon. This project addressed the unoptimized characterization test time of an Intel package quality control process. It improved throughput by developing a parallel testing method by increasing package carrier capacity and utilizing simultaneous testing. The final design led to a 4x increase of throughput rate.

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  • 2013-05