Materials Science and Engineering Commons^™

Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak

All Theses

The results in this thesis are from our efforts to modify the optical properties of solution-derived chalcogenide glass films by the incorporation of nanomaterials. First, the composition Ge23Sb7S70 was selected as the appropriate glass matrix for testing because solution-derived films of this composition have been well-studied in our group. Additionally, this composition was found to be less sensitive to certain processing parameters than As2S3, another well-studied, candidate chalcogenide glass composition, making Ge23Sb7S70 more suitable for the addition of nanomaterials. Optimization of film process parameters was performed to obtain high-quality films appropriate for doping with nanomaterials. This consisted of determining the …

Physiochemical And Nanomanipulation Studies Of Carbon Nanomaterials, Siva Naga Sandeep Chalamalasetty

Graduate Theses and Dissertations

Carbon nanomaterials are, without a doubt, one of man's wonder creations. Though these nanomaterials are a very recent trend, extraordinary electromechanical properties and the light weightiness of these nanomaterials attracted the attention of researchers. Although vast research has been done since the start of the US nanotechnology initiative, much effort was in the area of synthesis and characterization of the nanomaterials. However, most of the traditional macroscopic material's theories fail at the nanoscale level, and since the material properties are dependent on size and structure at nanoscale level, the behavior of the carbon nanomaterials in different environments needs attention. High …

Mott Transition And Electronic Structure In Complex Oxide Heterostructures, Jian Liu

Graduate Theses and Dissertations

Strongly correlated electron systems, particularly transition metal oxides, have been a focus of condensed matter physics for more than two decades since the discovery of high-temperature superconducting cuprates. Diverse competing phases emerge, spanning from exotic magnetism to unconventional superconductivity, in proximity to the localized-itinerant transition of Mott insulators. While studies were concentrated on bulk crystals, the recent rapid advance in synthesis has enabled fabrication of high-quality oxide heterostructures, offering a new route to create novel artificial quantum materials.

This dissertation details the investigation on ultrathin films and heterostructures of 3d⁷(t_2g⁶e_g¹) systems with …

Fabrication Of Vertical Silicon Nanowires Through Metal Assisted Deposition, Matthew Garett Young

Graduate Theses and Dissertations

Controlled and ordered growth of Si nanowires through a low temperature fabrication method compatible with CMOS processing lines is a highly desirable replacement to future electronic fabrication technologies as well as a candidate for a low cost route to inexpensive photovoltaics. This stems from the fact that traditional CMOS based electronics are hitting physical barriers that are slowing the Moore's Law trend as well as the demand for an inexpensive solar cell technology that can obtain grid parity. A fractional factorial growth study is presented that compares the growth of Au and Al catalyzed Si nanowires at temperatures ranging from …

Grain Boundaries Structures And Wetting In Doped Silicon, Nickel And Copper, Kaveh Meshinchi Asl

All Dissertations

This thesis reports a series of fundamental investigations of grain boundary wetting, adsorption and structural (phases) transitions in doped Ni, Cu and Si with technological relevance to liquid metal embrittlement, liquid metal corrosion and device applications. First, intrinsically ductile metals are prone to catastrophic failure when exposed to certain liquid metals, but the atomic level mechanism for this effect is not fully understood. A nickel sample infused with bismuth atoms was characterized and a bilayer interfacial phase that is the underlying cause of embrittlement was observed. In a second related study, we showed that addition of minor impurities can significantly …

A Conductivity Testing System Coupled With A Tensile Testing Machine To Measure The Surface Properties Of Polymer Specimens, Nguyen T. Nguyen

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Polymers play an essential role in our everyday life due to their employment in a widespread range of applications. Polymers are used in industries such as space, biomedical, electronics, etc. in which their electrical and mechanical properties are major aspects which need to be investigated prior to implementation. When subjected to mechanical stimulations, polymers may exhibit changes in electrical conductivity which can vary locally within the specimens, especially in those of conducting polymers. In mechanical investigations a tensile testing machine is used to understand polymers’ strength, elasticity or other mechanical properties. In electrical analysis, using a four-point probe to examine …

Template-Free Synthesis Of Porous Nio Hierarchical Structure For High Performance Supercapacitors, Yun Huang, Zhong Wu, Xin-Bo Zhang

Journal of Electrochemistry

A facile and template-free hydrothermal method is proposed to successfully synthesize porous NiO hierarchical structure, which is found to be assembled from ultrathin NiO nanosheets. As for electrochemical pseudocapacitor application, the obtained material exhibits not only high specific capacitances of 435 F·g^-1 at 20 mV·s^-1 and 367 F·g^-1 at 10 A·g^-1, but also holds a good electrochemical stability over 1000 cycles at a current rate of 20 mV·s^-1. These results suggest that the hierarchical structured porous NiO is a promising supercapacitor electrode material.

Electrochemical Reduction Of Co2 On Sn/Cu Electrodes, Chen-Chen Zhao, Jian-Wei Guo, Li Wang, Xiang-Ming He, Cheng Wang, Zhi-Xiang Liu

Journal of Electrochemistry

The Sn/Cu electrodes were prepared by electroplating method and their morphologies under different galvanization current densities were determined by SEM. In alkali, the effects of Sn/Cu electrodes on the activities towards hydrogen evolution and electrochemical reduction of CO₂ were investigated in alkaline solutions using a three-electrode system. These results indicated that the Sn/Cu electrodes prepared at 10 mA/cm² and 15 mA/cm² showed good activities, while that prepared at 15 mA/cm² was even better in activities. The synergetic structure of the Sn/Cu electrode to be beneficial to electrochemical reduction of CO₂ has been pointed out.

Ethanol Electrooxidation On Pt/Mo2/Cnts Catalysts, Yu-Long Cheng, Jie Sun, Ji-Gang Li, Li-Gong Zhang, Tian Zhou, Geng Chang, Zhong-Chao Dong

Journal of Electrochemistry

The ethanol electrooxidation behaviors on Pt/MO₂/CNTs（M=Sn, Ti, Ce）and Pt/CNTs catalysts in H₂SO₄ solutions were researched by cyclic voltammetry. It has revealed that the catalysts with the addition of metal oxides presented higher electrooxidation activity for ethanol, in particular, the Pt/CeO₂/CNTs catalyst showed the best activity for ethanol electrooxidation intermediate. The Pt/SnO₂/CNTs catalyst demonstrated the best ethanol electrooxidation activity when considering the synthetic effects of such parameters as the onset oxidation potential, peak current densities and total oxidation area.

Electrochemical Performances Of Carbon-Coated Na2Ti6O13 Nanotubes, Guo-Ran Li, Shuai Sun, Xue-Ping Gao

Journal of Electrochemistry

With rutile TiO₂ and NaOH as starting materials, the Na₂Ti₆O₁₃ nanotubes were prepared by a hydrothermal reaction. The carbon-coated Na₂Ti₆O₁₃ nanotubes were obtained by treating the Na₂Ti₆O₁₃ nanotubes for 4 h in glucose aqueous solutions containing 0.1 mol·L^-1 NaOH. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microcopy (TEM). The results showed that the dimensions of carbon-coated Na₂Ti₆O₁₃ nanotubes were 14 ~ 19 nm of outer diameter, 2 ~ 5 …

Electrochemical Preparation Of Nanostructural Pt-Ni And Pd-Ni Films For Ethanol Electro-Oxidation, Chen-Zhong Yao, Hui-Xuan Ma, Bo-Hui Wei

Journal of Electrochemistry

The Pt-Ni and Pd-Ni films were successfully prepared on Ti substrates by electrodeposition method. The porous Pt-Ni nanoflakes appeared to be uniform with the thickness of the slices about 10 ~ 20 nm. The porous Pd-Ni nanoparticles with a flower shape appeared to be uniform with the diameters of 50 ~ 60 nm. The XRD patterns also indicated that the Pd-Ni and Pt-Ni nanostructures have the poor crystallinity. The onset potentials of ethanol oxidation were negatively shifted to –0.74 V on Pt-Ni electrodes and –0.71 V on Pd-Ni electrodes, respectively. Addition of Ni could enhance catalytic activities and antitoxic properties …

Electrochemical Properties Of The Keggin-Type Lacunary Heteropolysilicate Anion And Its Eectrocatalysis For H2O2 Reduction, Xi-Long Liu, Chun-Yan Wu, Fang Zhou, Hong-Sheng Liu, Ying-Jie Hua, Chong-Tai Wang, Xiao-Yang Liu

Journal of Electrochemistry

Electrochemical properties of the Keggin-type lacunary heteropolysilicate anion SiW₁₁O₃₉^8- (SiW₁₁) and its indirect electrocatalysis for H₂O₂ reduction in the supporting electrolyte containing 0.1 mol·L^-1 NaHSO₄ and Na₂SO₄ solutions were investigated using cyclic voltammetry, square wave voltammetry and alternating current impedance spectroscopy. Experimental results indicated that SiW₁₁ showed two pairs of reversible redox waves on the glassy carbon (GC) electrode in an acidic solution. The electron transfer number corresponding to the two pairs of waves was one, and the proton transfer number involved was two during …

Corrosion Inhibition Of 316l Steel Using Sodium Diethyl Dithiocarbamate Solution In Simulated Crude Oil, Xiao-Guang Ren, Jie Yang

Journal of Electrochemistry

The corrosion inhibition behaviors of 316L steel using the sodium diethyl dithiocarbamate (SDDTC) compound in the crude simulation solution were studied in the absence and presence of zinc sulfate or sodium chromate with different compositions. Experiment resultss showed that in the environments of highly acidic and high concentrations of chloride ions the SDDTC compound could well inhibit the corrosion of 316L steel. The good synergic effects on the corrosion inhibition of 316L steel by additions of either zinc sulfate or sodium chromate into SDDTC compound were indicated in this study, which is of great significance and importance in practical applications.

NaXMYFe(Cn)6(M=Fe, Co, Ni): A New Class Of Cathode Materials For Sodium Ion Batteries, Jiang-Feng Qian, Min Zhou, Yu-Liang Cao, Han-Xi Yang

Journal of Electrochemistry

Three types of Prussian blue compounds, Na_xM_yFe(CN)₆ (M = Fe, Co, Ni), were prepared simply by solution precipitation method and tested as cathode materials for sodium-ion batteries. X-ray diffraction and SEM measurements demonstrated that the prepared materials, namely, NaFeFe(CN)₆, Na₂CoFe(CN)₆, and Na₂NiFe(CN)₆, exhibited a perfect cubic structure with a particle size of several tens nanometers. Cyclic voltammetric and galvanostatic cycling tests revealed very different electrochemical behaviors of these three materials. The specific capacities of NaFeFe(CN)₆ and Na₂CoFe(CN)₆ could reach 113 mAh·g …

Preparation And Electrochemical Performance Of Mo-Doped Li3V2(Po4)3/C Cathode Materials, Zhi-Yuan Tang, Wei Yuan, Ji Yan, Wen-Feng Mao, Li Ma

Journal of Electrochemistry

The molybdenum-doped Li₃V_2-xMo_x(PO₄)_3/C (x = 0.01, 0.02 and 0.03) cathode materials were prepared with a sol-gel method by using Li₂CO₃, NH₄H₂PO₄, V₂O₅ and MoO₃ as raw materials, and citric acid as both chelating reagent and carbon source. The X-ray diffraction (XRD) analyses showed that the crystal structure of as-prepared samples is monoclinic with space group P2₁/n. Scanning electron microscopy (SEM) observations indicated the uniform morphology for Li₃Mo_0.02V_1.98(PO₄) …

Synthesis Of Lini0.5Co0.2Mn0.3O2 For Lithium Ion Batteries And The Mechanism Of Capacity Fading At High Temperature, Wen Liu, Miao Wang, Ji-Tao Chen, Xin-Xiang Zhang, Heng-Hui Zhou

Journal of Electrochemistry

The Ni-rich cathode materials, LiNi_0.5Co_0.2Mn_0.3O₂, have been synthesized by Co-precipitation and high-temperature solid-phase sintering method. Constant current charge-discharge tests showed high discharge capacity of 179.2 mAh·g^-1 in the 3.0~4.4 V at 0.2C. However, at 55 °C the LiNi_0.5Co_0.2Mn_0.3O₂ experienced the dramatic capacity fading after 100 charge-discharge cycles. Electrochemical Impedance Spectroscopy, X-Ray Photoelectron Spectroscopy, Atomic Emission Spectroscopy have been employed to study the capacity fading mechanism of LiNi_0.5Co_0.2Mn_0.3O₂ cycled at high temperature in range of high-voltage charge and …

Synthesis And Electrochemical Properties Of Lifeso4F/Graphene Composite As Cathode Material For Lithium-Ion Batteries, Wei Guo, Ya-Xia Yin, Li-Jun Wan, Yu-Guo Guo

Journal of Electrochemistry

The LiFeSO₄F was successfully synthesized from the reactions of FeSO₄∙xH₂O (x=1, 4, 7) with LiF in tetraethylene glycol media through a facile low temperature method. The structures and microscopic features of the products were characterized by XRD, SEM and TEM. TGA result shows the good thermal stability of the as-prepared LiFeSO₄F. No diffraction peaks of the FeSO₄ are observed in the as-prepared products with the starting material of either FeSO₄∙4H₂O or FeSO₄∙7H₂O, which should be ascribed to delaying the release of H_{2 …}

Synthesis And Electrochemical Properties Of Yttrium-Doped Lini0.49Mn1.49Y0.02O4, Xian-Wen Zhang, Zheng-Xi Zhang, Li Yang, Shao-Hua Fang, Long Qu

Journal of Electrochemistry

The LiNi_0.49Mn_1.49Y_0.02O₄ cathode material was synthesized using the citric acid-assisted sol-gel method by partial substitutions of Ni and Mn with Y in the LiNi_0.5Mn_1.5O₄ material. The influences of Y doping on the structure and electrochemical properties were investigated by means of X-ray diffraction, cyclic voltammetry, galvanostatic charge/discharge tests and AC impedance spectroscopy. The results showed that the introduction of Y into the LiNi_0.5Mn_1.5O₄ greatly improved the cycle performance and rate capability. When the charge and discharge current was 1 C in the potential …

Catalytic Activities Of Electrochemically Dealloyed Pt(Pd)-Cu Catalysts For Oxygen Reduction Reaction, Rui-Zhi Yang, Strasser Peter, Toney Michael

Journal of Electrochemistry

The electrochemically dealloyed Pt(Pd)-Cu catalysts were prepared by electrochemical dealloying of Cu₃Pt(Pd) and their catalytic activities toward oxygen reduction reaction (ORR) were studied in 0.1 mol·L^-1 HClO₄ . solutions. The structural features of the dealloyed Pt(Pd)-Cu were revealed by synchrotron-based anomalous X-ray diffraction (AXRD) and surface X-ray scattering (SXS) at an atomic scale. We established a relationship between the structure and the catalytic activity by comparing the ORR activity and the structure of dealloyed Cu₃Pt nanoparticles with similarly dealloyed Cu₃Pt thin films and Cu₃Pt(111). The enhancement in the activity of …

Electrocatalytic Oxidation Of Ethanol On Ni-P-Tio2 Composite Coating Electrodes, Guang-Hui Hu, Hai-Xia Zeng, Zhi-Gang Wei, Zhan-Chang Pan, Shu-Guang Xie, Yan-Di Zou

Journal of Electrochemistry

The Ni-P-TiO₂ composite coating electrodes with different contents of TiO₂ particulates were prepared by electroless plating technique from Ni-P plating bath containing TiO₂ powders on brass. Cyclic voltammetry, linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) were used to test the electrochemical performance of Ni-P-TiO₂/Cu electrodes. It was indicated that the Ni-P-TiO₂/Cu electrodes exhibited very strong electrocatalytic activity toward the oxidation of ethanol in alkaline medium at ambient temperature. The electrocatalytic activity of ethanol oxidation on the Ni-P-TiO₂ electrodes depended on the amounts of TiO₂ in the coatings. The …

Solar Cell Design Using Metamaterials, Yang Liu, Yitung Chen, Jichun Li

College of Engineering: Graduate Celebration Programs

Natural structure with simultaneous negative permittivity and permeability has not been discovered yet. However, using specially-designed metal embedded in dielectric bodies can achieve a kind of artificial negative index. This periodic structure which is smaller than the guided wavelength is known as a metamaterial. However, recent designs of metamaterials have some disadvantages when they are used in the application of solar cell. The perfect absorption is only within a narrow band, and for most of the solar spectrum, the absorption is no more than 10%. Here, a new kind of absorber for the solar spectrum has been designed and analyzed, …

Nano-Silica For Enhanced Greener Concrete, Mohamed S. Zeidan

College of Engineering: Graduate Celebration Programs

Colloidal nano-silica was added to normal and fly ash concretes with different rates to examine the its effect on different concrete performance aspects. The main objectives of the study is to determine the effect of adding nano-silica on:

• The rate hydration and the reactivity of cement and pozzolans.

• The mechanical properties and strength gain rate (especially for fly ash concrete).

• Durability.

• Microstructure and Porosity.

Cellular Automaton For Simulation Of Oxide Layer Growth Influenced By Chromium Concentration Of Structure Material, Kuan-Che Lan, Yitung Chen, Ge-Ping Yu, Tzu-Chen Hung

College of Engineering: Graduate Celebration Programs

Chromium, an important alloying element, has been added in ferrous and nickel based alloy such as stainless steels and Inconel alloy to improve the corrosion resistance. High corrosion resistance of structural materials in extremely high working temperature is one crucial R&D objective of Gen IV nuclear power plants which propose to raise the thermal efficiency via high working temperature. A cellular automaton (CA) model based on the stochastic approach was proposed to simulate the process of oxidation and corrosion of structural material in flowing fluid. The relation of chromium concentration against oxide layer thickness during a specific period was found. …

Repairing Mixed-Conducting, Ceramic Electrolyte Films, Kevin Tolman, Izaak Williamson, Kokfoong Chan

College of Engineering Poster Presentations

Ceramatec, Inc. develops ceramic-electrolyte thin films for gas separation/purification technologies. Specific ions (e.g., oxygen) can be selectively diffused through these films in order to obtain a desired product, such as syngas or pure O2. During production, residual stresses develop within the films which induce defects, such as pinholes, micro-cracks, and other sources of leaks, that allow gas contamination. To improve large-scale film production yield, four application techniques were analyzed for their feasibility of restoring the integrity of the films. Controlled, uniform defects were introduced to the films using a microindenter to enable an effective comparison of application techniques …

Particle Size Characterization Of Ferritic Oxide Dispersion Strengthened Alloy Powders, Sumit R. Tamrakar

College of Engineering Poster Presentations

Ferritic oxide dispersion strengthened (ODS) alloys are candidate materials for use in extreme applications due to their excellent high temperature strength. Fe₈₁Cr₁₆Mo₃ and Fe₈₁Cr₁₆Al₃ alloys were ball milled for various durations with 0.5 wt. % Y₂O₃ nanometer sized particles prior to consolidation via spark plasma sintering (SPS). The particle size characterization was completed using optical microscopy, scanning electron microscopy (SEM), and laser scattering. The median particle size of Fe₈₁Cr₁₆Mo₃₊0.5 wt. % Y₂O₃ powder increased from 9µm to 31µm …

Versatile In-Situ Engine Lubricant Health Sensor, Sanjeev Acharya

College of Engineering Poster Presentations

Lubricants which are used in engines to reduce friction, promote engine cooling, and prevent corrosion degrade with time under harsh engine operating conditions and hence need to be changed periodically. Since degradation of oil is a result of number of mechanisms such as; engine component wear, oil oxidation, water ingress, and carbon particles, a versatile and microscopic in-situ sensor that can sense quality of wide variety of engine lubricant brands at various temperatures and pressures is of great need. This problem can be resolved by applying portable interdigitated micro-sensors to examine the impedance behavior of degraded lubricants through electrochemical tests. …

Synthesis And Characterization Of Aluminum Doped Zinc Oxide Nanowires For Photovoltaic Devices And Semiconductors, Travis J. Wilson^, Md. Ashiqur R. Khan, Mohammad A. I. Shuvo, Miguel Mendoza, Matthew Garcia, Yirong Lin*, Chintalapalle V. Ramana*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Sic-Cnt Multifunctional Nanocomposites For High Temperature Structural, Thermoelectric And Sensing Applications, Luisa A. Cabrera^, Arifur Chowdhury, Onasis Garcia, Mujibur R. Khan*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Functional Magnetic Nanoparticles, James Gass

USF Tampa Graduate Theses and Dissertations

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields.

Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy …

The Implementation Of A Visco-Hyperelastic Numerical Material Model For Simulating The Behaviour Of Polymer Foam Materials, Conor Briody, Barry Duignan, Stephen Jerrams, John Tiernan

Articles

Polyurethane foam has been in use for some time in wheelchair seating systems as it offers good pressure relieving capabilities in most cases. However, little characterisation work has gone into seating foam materials by comparison with conventional elastomeric materials. Accurate material models could allow better prediction of foam in-service behaviour, which could potentially improve seating design practises. The objective of this work was to develop an approach for the validation of hyperelastic and viscoelastic material model parameters used to simulate polyurethane foam behaviour. Material parameters were identified from relevant test procedures and implemented in a Finite Element simulation of an …