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Articles 1 - 17 of 17
Full-Text Articles in Engineering
A Study Of Wo3 And W0.95ti0.05o3 Thin Films Using Comparative Spectroscopy, James Heyward Howard
A Study Of Wo3 And W0.95ti0.05o3 Thin Films Using Comparative Spectroscopy, James Heyward Howard
Open Access Theses & Dissertations
Tungsten oxide (WO3) is important and well-studied in materials science, particularly for sensor applications. In this research work, we consider the innovation of adding Ti to thin films of this material. Since the characteristics of any such material are strongly dependent on the conditions and methods used in its deposition, the main objective of this project is to provide a detailed spectroscopic characterization by Raman scattering, infrared absorption, and X-ray photoelectron spectroscopy (XPS) of WO3 and of W0.95Ti0.05O3. This characterization will be based on comparison of the morphology and composition of WO3-based thin films, grown by radio frequency magnetron reactive …
Nanoprobe I-V Characterization Of Cdte/Cds Micro And Nano-Patterned Solar Cells, Heber Prieto
Nanoprobe I-V Characterization Of Cdte/Cds Micro And Nano-Patterned Solar Cells, Heber Prieto
Open Access Theses & Dissertations
This thesis presents a novel way to characterize micro and nano patterned cadmium telluride thin film solar cells via a nano-probe system. A historical review of CdTe-based solar cells is presented first followed by review of the technology developed to produce the patterned CdTe cells. A detailed presentation is then provided on the use of a Zyvex nanoprobing system to characterize the patterned solar cells. The I-V response of micro- and nano-patterned solar cells stimulated under different e-beam conditions is presented and analyzed. Suggestions of how to improve the technique are provided. This work documents, for the first time, the …
High Pressure Synchrotron X-Ray Diffraction Studies Of Superprotonic Transitions In Phosphate Based Solid Acids, Juan Daniel Hermosillo
High Pressure Synchrotron X-Ray Diffraction Studies Of Superprotonic Transitions In Phosphate Based Solid Acids, Juan Daniel Hermosillo
Open Access Theses & Dissertations
Certain phosphate based solid acids, such as CsH2PO4 and RbH2PO4, have been shown to exhibit an abrupt, several-order-of-magnitude increase in their proton conductivity when heated above a temperature threshold. This so called superprotonic behavior allows the above-mentioned materials to function as fuel cell electrolytes at temperatures between 150C and 300C, a remarkable application that attracted significant interest especially from the automobile industry. Yet, the microscopic structures and dynamic mechanisms responsible for this behavior are not fully understood. In fact, until very recently, the very nature of the superprotonic behavior has been debate, with some groups attributing the steep proton enhancement …
Development Of Nanocomposites For Energy Storage Devices, Md Ashiqur Rahaman Khan
Development Of Nanocomposites For Energy Storage Devices, Md Ashiqur Rahaman Khan
Open Access Theses & Dissertations
With the ever-increasing need in improving the performance and operation life of future mobile devices, developing higher power density energy storage devices has been receiving more attention. Lithium ion battery (LIB) and capacitor are two of the most widely used energy storage devices and have attracted increasing interest from both industrial and academic fields. Batteries have higher power density than capacitor but significantly longer charge/discharge rates. In order to further improve the performance of these energy storage devices, one of the approaches is to use high specific surface area nano-materials. Among all the nano-materials developed so far, one-dimensional nanowires are …
The Influence Of Build Parameters On The Microstructure During Electron Beam Melting Of Ti6al4v, Karina Puebla
The Influence Of Build Parameters On The Microstructure During Electron Beam Melting Of Ti6al4v, Karina Puebla
Open Access Theses & Dissertations
With the demand of devices to replace or improve areas, such as: electronic, biomedical and aerospace industries. Improvements in these areas of engineering have been in need due to the customer’s needs for product properties requirements. The design of components must exhibit better material properties (mechanical or biocompatible) close to those of any given product. Rapid prototyping (RP) technologies that were originally designed to build prototypes may now be required to build functional end-use products. To carry out the transition, from RP to rapid manufacturing (RM), the available materials utilized in RP must provide the performance required for RM. The …
Structure Morphology And Optical Properties Of Nanocrystalline Ga2o3 Thin Films, Sampath Kumar Samala
Structure Morphology And Optical Properties Of Nanocrystalline Ga2o3 Thin Films, Sampath Kumar Samala
Open Access Theses & Dissertations
Gallium Oxide thin films were produced by sputter deposition by varying the substrate temperature (Ts) in a wide range (Ts=25-800 oC) and under variable deposition time. The structural characteristics and optical properties of Ga2O3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga2O3 films. XRD and SEM analyses indicate that the Ga2O3 films grown at lower temperatures were …
The Effects Of Uncommon Silicides On The Oxidation Of Alloys From The Nb-Cr-Si System, Daniel Brendan Voglewede
The Effects Of Uncommon Silicides On The Oxidation Of Alloys From The Nb-Cr-Si System, Daniel Brendan Voglewede
Open Access Theses & Dissertations
Niobium based alloys are being tapped as potential successors to current nickel base superalloys in high temperature applications. In the aerospace industry, high temperature materials are constantly being pushed to higher temperature regimes in order to improve engine efficiency however current superalloys cannot be pushed further due to melting temperature limitations. Niobium, being a refractory metal, can withstand much higher temperatures than nickel however its oxidation properties are woefully inadequate.
The purpose of this study is to ascertain whether increased silicon additions can improve niobium oxidation properties by: forming ternary silicides with better oxidation properties and by preventing the formation …
Raman And Infrared Study Of Electrospun Plla/Pcl Nanofiber Blends For Use In Tissue Engineering, Jose Luis Enriquez Carrejo
Raman And Infrared Study Of Electrospun Plla/Pcl Nanofiber Blends For Use In Tissue Engineering, Jose Luis Enriquez Carrejo
Open Access Theses & Dissertations
Recently, the biomedical engineering field has developed at a very fast pace as improved techniques and materials become available to promote its growth. Consequently, the research in polymeric biomaterials has been highly stimulated by this trend. The goal of the current research is to demonstrate the usefulness of the Raman scattering, Raman mapping, and infrared absorption spectroscopies to tissue engineering, by spectroscopically characterizing blends of PLLA and PCL polymers, which were prepared by electrospinning with and without cell addition. The proposed use of these blends is as primary biomaterials in biodegradable scaffolds used in tissue engineering. Both Raman and infrared …
Development Of A Multi-Material, Multi-Technology Fdm System For Process Improvement Experimentation, David Espalin
Development Of A Multi-Material, Multi-Technology Fdm System For Process Improvement Experimentation, David Espalin
Open Access Theses & Dissertations
Over the last three decades, developments within the area of Additive Manufacturing (AM) have resulted in novel technologies capable of producing highly customized, complex part geometries in a fraction of the lead time required by traditional manufacturing methods (e.g., injection molding, metal casting). In particular, fused deposition modeling (FDM), a material extrusion AM process, can produce parts using production-grade thermoplastics like acrylonitrile butadiene styrene, polycarbonate, and polyetherimide. Additionally, non-commercial materials (e.g., polycaprolactone, ceramic loaded polymers, carbon nanotube loaded polymers) have been processed using FDM in part to demonstrate the potential diversity in material selection.
Recently, a myriad of personal 3D …
Thin Film Growths Of Znte And Cdte On Various Substrates Using A Novel Close Space Sublimation Reactor Css4, Damian Marrufo
Thin Film Growths Of Znte And Cdte On Various Substrates Using A Novel Close Space Sublimation Reactor Css4, Damian Marrufo
Open Access Theses & Dissertations
Thin films of CdTe have been grown on CdS in a variety of methods for use in thin film photovoltaic systems. Limits to the efficiency of CdTe/CdS solar cells have been attributed to defects in the lattice that occur between the interface of CdS and CdTe due to a lattice mismatch. A close space sublimation (CSS) reactor known as the CSS4 was designed and fabricated in UTEP to deposit complex layers of CdTe and ZnTe on top of a CdS film that is grown via chemical bath deposition in order to obtain a CdTe photovoltaic. Unfortunately, the original design and …
Development Of Advanced Polymer Nanocomposite Capacitors, Miguel Mendoza
Development Of Advanced Polymer Nanocomposite Capacitors, Miguel Mendoza
Open Access Theses & Dissertations
The current development of modern electronics has driven the need for new series of energy storage devices with higher energy density and faster charge/discharge rate. Batteries and capacitors are two of the most widely used energy storage devices. Compared with batteries, capacitors have higher power density and significant higher charge/discharge rate. Therefore, high energy density capacitors play a significant role in modern electronic devices, power applications, space flight technologies, hybrid electric vehicles, portable defibrillators, and pulse power applications. Dielectric film capacitors represent an exceptional alternative for developing high energy density capacitors due to their high dielectric constants, outstanding breakdown voltages, …
Oxidation Of Borides And Carbides With Y2o3 And Ta Additions, Salvador Manuel Rodriguez
Oxidation Of Borides And Carbides With Y2o3 And Ta Additions, Salvador Manuel Rodriguez
Open Access Theses & Dissertations
The study presented here describes an investigation of an oxidation scale of a fully-sintered Y2O3-ZrB2-TiC composite exposed in air at 1173K. Upon oxidation of the boride/carbide, a ZrO2-TiO2 was expected to form similar to the ZrO2-SiO2 dual scale of an oxidized ZrB2-SiC. The 47wt% Y2O3-38wt%ZrB2-16wt%TiC composite formed a dual scale consisting primarily of an Y2O3-ZrO2-TiC inner scale with an outer scale of ZrO2-TiO2-Y2O3.
The samples oxidized with a parabolic layer growth allowing the calculation of the effective diffusion coefficient indicating that the oxidation was controlled by oxygen ingress through primarily the ZrO2-Y2O3 phase. The oxygen potential between the inner layer …
Hafnia-Based Nanostructured Thermal Barrier Coatings For Next Generation Gas Turbine Technology, Mohammed Noor-A-Alam
Hafnia-Based Nanostructured Thermal Barrier Coatings For Next Generation Gas Turbine Technology, Mohammed Noor-A-Alam
Open Access Theses & Dissertations
Extensive efforts have been directed in the last several decades towards improving thermodynamic efficiency of industrial gas turbines for power generation plants. The central theme of the efforts is to increase the turbine operating temperature and, thus, allowing higher efficiency. Thermal barrier coatings (TBC) constitute an advanced technology to protect the metallic surface from high temperature exposure for long time operation. The TBCs protect the gas turbine components from high temperature and allows further increase in engine operating temperature which subsequently increases the efficiency of the gas turbine power plant. However, the current TBC materials are capable of allowing the …
Applications Of Density Functional Theory In Materials Science And Engineering, Manuel Alvarado
Applications Of Density Functional Theory In Materials Science And Engineering, Manuel Alvarado
Open Access Theses & Dissertations
Density Functional Theory (DFT) is a powerful tool that can be used to model various systems in materials science. Our research applies DFT to two problems of interest. First, an organic/inorganic complex dye system known as a Mayan pigment is modeled to determine chemical binding sites, verifying each model with physical data such as UV/Vis spectra. Preliminary studies on palygorskite-based mayan pigments (mayacrom blue, mayacrom purple) show excellent agreement with experimental studies when using a dimer dye geometry binding with tetrahedrally-coordinated aluminum impurity sites in palygorksite. This approach is applied to a sepiolite-based organic/inorganic dye system using thioindigo attached to …
The Effect Of Al And B Additions On The Oxidation Behavior Of Alloys From The Nb-Cr-Si System, Nydia Judit Esparza
The Effect Of Al And B Additions On The Oxidation Behavior Of Alloys From The Nb-Cr-Si System, Nydia Judit Esparza
Open Access Theses & Dissertations
Nickel based superalloys have been developed to perform substantially in industry however as technology develops, the need and desire to increase service temperatures to improve efficiency and performance is pushing the capabilities of these alloys. These aspired requirements entail the research and development of new structural materials that surpass the abilities of nickel alloys. Research in Nb-based alloys is underway as Nb alloys have shown to be a promising alternative with similar density but higher melting temperatures than the Ni alloys. However, because Nb has poor oxidation properties extensive studies are necessary to develop an alloy that can perform as …
The Effect Of Al, Mo, And B On The Oxidation Behavior Of Three Nb-Based Alloys, Victoria Rae Rangel
The Effect Of Al, Mo, And B On The Oxidation Behavior Of Three Nb-Based Alloys, Victoria Rae Rangel
Open Access Theses & Dissertations
Extensive work has been undertaken to develop niobium based structural alloys for high temperature applications. These developments have led to the increase in engine operating temperatures and better performance efficiency. New materials including alloys based on metals with higher melting points such as molybdenum and niobium with silicon are now being examined as a better alternative to nickel base superalloys. Materials with a niobium silicide based composites have the potential for higher temperature capabilities. The oxidation behavior of Nb-20Cr-10Si and Nb-20Cr-10Si-5Al has been studied in a range of temperature from 700 to 1400°C in static air. Isothermal oxidation experiments indicate …
A Novel Method For The Curing Of Metal Particle Loaded Conductive Inks And Pastes, David Adrian Roberson
A Novel Method For The Curing Of Metal Particle Loaded Conductive Inks And Pastes, David Adrian Roberson
Open Access Theses & Dissertations
The emerging technology of printed microelectronics involving the use of conductive inks in conjunction with standard printing techniques offers a fast and low waste method for creating microelectronics compared with standard manufacturing processes. A clear path to the creation of flexible electronics is present due to the ease of printing on flexible substrates. Moreover, creation of novel 3D structural electronics is possible via the integration of printing technologies and additive manufacturing (AM) techniques.
A key obstacle to the manufacturing of flexible and structural electronics comes from the temperature restrictions imposed by the substrates, which are typically polymeric. This hindrance has …