Materials Science and Engineering Commons^™

Fundamental Studies Of Chemical Stability And Carrier Process In Hybrid Perovskite Materials, Jue Gong

Graduate Research Theses & Dissertations

This dissertation comprehensively studies the optoelectronic properties of organic-inorganic hybrid perovskites to fundamentally answer their foundations of outstanding performance on solar cells, photodetectors, nanowire lasers and other optoelectronic applications. Specifically, a novel type of charge carrier-lattice interaction was discovered in perovskite methylammonium lead iodide (CH3NH3PbI3), where photoluminescence lifetime of photoinduced carriers is strongly dependent on the rotational frequency of CH3NH3+, as modulated via substitution of hydrogens with deuterium atoms in the organic cation. In addition, two-dimensional Ruddlesden-Popper perovskite (CH3NH3)2Pb(SeCN)2I2 was first synthesized and characterized in the field, and its photoluminescence properties were systematically examined. The existence of intensive photoluminescence peak …

Surface Engineering And Monomer Design For Light-Mediated Ring Opening Metathesis Polymerization, Ishan A. Fursule

Theses and Dissertations--Chemical and Materials Engineering

Stimuli-responsive materials are changing the landscape of actuated materials, optoelectronics, molecular machines, solar cells, temporary memory storage, and biomedical materials. Specifically, photo-responsive polymers have gained acceleration in research and application since the last two decades in the form of a surface coating and micro-patterns. Light as a stimulus can be coherent, mono or polychromatic, tunable for power (intensity) and energy (wavelength), and has precise spatiotemporal control. Conventional surface coating techniques such as spin coating are unable to impart properties to the coatings in terms of sturdiness, homogeneity, uniformity over the complex surface, post deposition modification, and process efficiency. Also, in …

Combinatorial Screening Approach In Developing Non-Equiatomic High Entropy Alloys, Azin Akbari

Theses and Dissertations--Chemical and Materials Engineering

High entropy alloys (HEA) are a relatively new group of alloys first introduced in 2004. They usually contain 5 to 6 different principle elements. Each of these elements comprise 5-35 at. % of the chemical composition of the alloy. There is a growing interest in the research community about the development of these alloys as well as their engineering applications. Some HEAs have interesting properties that have made them well suited for higher temperature applications, particularly refractory uses, while some have been shown to maintain their mechanical properties even at cryogenic temperatures.

Initially, the HEA research was focused on developing …

A Microstructure-Based Model Validated Experimentally For Quantification Of Short Fatigue Crack Growth In Three-Dimensions, Pei Cai

Theses and Dissertations--Chemical and Materials Engineering

Built on the recent successes in understanding the crystallographic mechanism for short fatigue crack (SFC) growth across a grain boundary (GB) and developing an experimental method to quantify the GB resistance against short crack growth, a microstructure-based model was developed in this study to simulate the growth behaviors of SFCs in 3-D, by taking into account both the driving force and resistance along at each point along the crack front in an alloy. It was found that the GB resistance was a Weibull function of the minimum twist angle of crack deflection at the boundary in AA2024-T3 Al alloys. In …

Defect Chemistry And Transport Properties Of Solid State Materials For Energy Storage Applications, Xiaowen Zhan

Theses and Dissertations--Chemical and Materials Engineering

Replacing organic liquid electrolytes with nonflammable solid electrolytes can improve safety, offer higher volumetric and gravimetric energy densities, and lower the cost of lithium-ion batteries. However, today’s all-solid-state batteries suffer from low Li-ion conductivity in the electrolyte, slow Li-ion transport across the electrolyte/electrode interface, and slow solid-state Li-ion diffusion within the electrode. Defect chemistry is critical to understanding ionic conductivity and predicting the charge transport through heterogeneous solid interfaces. The goal of this dissertation is to analyze and improve solid state materials for energy storage applications by understanding their defect structure and transport properties.

I have investigated defect chemistry of …

Mixed Matrix Flat Sheet And Hollow Fiber Membranes For Gas Separation Applications, Nicholas W. Linck

Theses and Dissertations--Chemical and Materials Engineering

Mixed matrix membranes (MMM) offer one potential path toward exceeding the Robeson upper bound of selectivity versus permeability for gas separation performance while maintaining the benefits of solution processing. Many inorganic materials, such as zeolites, metal-organic frameworks, or carbon nanotubes, can function as molecular sieves, but as stand-alone membranes are brittle and difficult to manufacture. Incorporating them into a more robust polymeric membrane matrix has the potential to mitigate this issue.

In this work, phase inversion polymer solution processing for the fabrication and testing of asymmetric flat sheet mixed matrix membranes was employed with CVD-derived multiwall carbon nanotubes (MWCNTs) dispersed …

The Formation Mechanism Of Α-Phase Dispersoids And Quantification Of Fatigue Crack Initiation By Experiments And Theoretical Modeling In Modified Aa6061 (Al-Mg-Si-Cu) Alloys, Gongwang Zhang

Theses and Dissertations--Chemical and Materials Engineering

AA6061 Al alloys modified with addition of Mn, Cr and Cu were homogenized at temperatures between 350 ^ºC and 550 ^ºC after casting. STEM experiments revealed that the formation of α-Al(MnFeCr)Si dispersoids during homogenization were strongly affected by various factors such as heating rate, concentration of Mn, low temperature pre-nucleation treatment and homogenization temperature. Through analysis of the STEM results using an image software Image-Pro, the size distributions and number densities of the dispersoids formed during different annealing treatments were quantitatively measured. It was revealed that increasing the heating rate or homogenization temperature led to a reduction of …

Synthesis And Characterization Of Magnesium - Titanium Composites By Severe Plastic Deformation, Baleegh Alobaid

Theses and Dissertations--Chemical and Materials Engineering

Magnesium alloys are widely used in engineering applications, including aerospace and automobile industries, due to their desirable properties, such as lower density, high damping capacity, relatively high thermal conductivity, good machinability, and recyclability. Researchers have, therefore, been developing new magnesium materials. However, mechanical and corrosion properties are still limiting many commercial applications of magnesium alloys. In this Ph.D. thesis research, I developed Mg-Ti composite materials to offer some solutions to further improve the mechanical behavior of magnesium, such as titanium-magnesium (Ti-Mg) claddings, Mg-Ti multilayers, and Ti particle enforced Mg alloys. Low cost manufacturing processes, such as hot roll-bonding (RB) and …

The Physical Behavior And Characterization Of Nanoporous Silicon And Dispenser Cathode Surfaces, Tyler Lucius Corey Maxwell

Theses and Dissertations--Chemical and Materials Engineering

Nanostructured materials have received a surge of interest in recent years since it has become apparent that reducing the size of a material often leads to heightened mechanical behavior. From a fundamental standpoint, this stems from the confinement of dislocations. Applications in microelectromechanical devices, lithium ion batteries, gas sensing and catalysis are realized by combining the improvements in mechanical behavior from material size reduction with the heightened chemical activity offered by materials with a high surface-area-to-volume ratio. In this study, films of nanoporous Si-Mg were produced through magnetron sputtering, followed by dealloying using an environmentally benign process with distilled water. …

Morphological And Energetic Effects On Charge Transport In Conjugated Polymers And Polymer-Nanowire Composites, Zhiming Liang

Theses and Dissertations--Chemistry

Organic semiconductors have wide applications in organic-based light-emitting diodes, field-effect transistors, and thermoelectrics due to the easily modified electrical and optical properties, excellent mechanical flexibility, and solution processability. To fabricate high performance devices, it is important to understand charge transport mechanisms, which are mainly affected by material energetics and material morphology. Currently it is difficult to control the charge transport properties of new organic semiconductors and organic-inorganic nanocomposites due to our incomplete understanding of the large number of influential variables. Molecular doping of π-conjugated polymers and surface modification of nanowires are two means through which charge transport can be manipulated. …

Comparative Study Of Cv3 Carbonaceous Chondrites Allende And Bali Using Micro-Raman Spectroscopy And Sem/Eds, Raka Paul

All Graduate Theses, Dissertations, and Other Capstone Projects

The birth of the solar system (over 4 billion years) is speculated to have happened from a nebula, swirling and compacting in localized regions to eventually form the Sun and planets. This complex process consists of numerous changes and intermediary steps, yet to be fully understood. Carbonaceous chondritic meteorites are relics of that process and therefore have potential to reveal information about the formation history. Several theories have been formulated linking their composition to planet formation. This study focusses on two carbonaceous chondritic specimens, Allende and Bali, both of the group CV and petrologic type 3. CV meteorites are abundant …

Fe73.5si13.5b9cu1nb3 Metallic Glass: Rapid Activation Of Peroxymonosulfate Towards Ultrafast Eosin Y Degradation, Jincheng Wang, Zhe Jia, Peng Qin, W. C. Zhang, M. D. Wang, T. B. Sercombe, Laichang Zhang

Research outputs 2014 to 2021

Discovering functional applications of metallic glasses (MGs) as heterogeneous catalysts is a fundamental and essential topic. This work reports the rapid production of sulfate radicals (SO₄⁻) from peroxymonosulfate (PMS) using Fe_73.5Si_13.5B₉Cu₁Nb₃ glassy ribbons as catalysts for Eosin Y (EY) dye wastewater treatment. The reaction rates (k) from the experimental data reveal that the EY degradation is well fitted with the pseudo-first-order kinetic model. The strong electron transfer ability is characterized by electrochemical methods, presenting an advanced catalytic performance for EY degradation. Various experimental parameters, including dye …

Photonic Crystal-Supported Long-Range Surface Plasmon-Polaritons Propagating Along High-Quality Silver Nanofilms, Sergey K. Sekatskii, Anton Smirnov, Giovanni Dietler, Mohammad Nur E. Alam, Mikhail Vasiliev, Kamal Alameh

Research outputs 2014 to 2021

Long-range surface plasmon-polaritons (LRSPP) with a propagation length equal to 180 microns at the wavelength of 633 nm have been observed at the interface of 12.5 nm-thick silver nanofilm, coated by a 20 nm-thick protective ZnS layer, with air. Their propagation has been supported by a specially prepared 40-layer 1D Photonic Crystal designed in such a manner that silver layer has been deposited directly onto thin ZnS layer, earlier shown to be a non-oxide material most suitable for the preparation of high-quality thin silver nanofilms.

A New Approach To Multiplanar, Real-Time Simulation Of Physiological Knee Loads And Synthetic Knee Components Augmented By Local Composition Control In Fused Filament Fabrication, Joshua Taylor Green

Open Access Theses & Dissertations

Despite numerous advances in biomedical engineering, few developments in surgical simulation have been made outside of computational models. Cadavers remain the primary media on which surgical research and simulation is conducted. Most attempts to quantify the effects of orthopedic surgical methods fail to achieve statistical significance due to limited quantities of cadaver specimen, large variations among the cadaver population, and a lack of repeatability among measurement techniques. The general purpose of the research covered in this dissertation is to develop repeatable simulation of physiological loads and develop techniques to fabricate a synthetic-based replacement of cadaver specimens. Future work applying this …

Streamlining Alloy Design And Thermo-Mechanical Processing Parameters For High Strength Line Pipe Steels And Hot Rolled Microalloyed Steels: Process - Structure - Property Paradigm, Venkata Vignesh Natarajan

Open Access Theses & Dissertations

The process parameters related to thermo-mechanical controlled processing (TMCP) of steels play a vital role in affecting the ultimate mechanical properties. We illustrate here the impact of coiling temperature, the impact of finish cooling temperature on interrupted cooling and compare with continuous cooling, and the impact of carbon and niobium on the microstructure and precipitation behavior and corresponding changes in mechanical properties, in an ultrahigh strength titanium-niobium microalloyed steel. The microstructural advancement was contemplated via transmission electron microscopy and electron backscattered diffraction (EBSD). The goal was to underscore the impact of coiling temperature on the nature and distribution of microstructural …

Heterogeneous Integration Of Metallic, Semiconducting And Dielectric Two-Dimensional Layered Material Inks For Electronics And Sensing Device Platforms, Jay Amrish Desai

Open Access Theses & Dissertations

In monolayers of two-dimensional (2-D) layered materials, the motion of electrons is confined to a 2-D plane yielding a "zero" effective thickness with regard to the electrons. These monolayers are commonly obtained by exfoliating membranes from the bulk crystal to overcome the weak interplanar Van der Waals bonding using the so-called top-down approach. The bottom-up approach is another avenue to realize these materials, where atoms and molecules coalesce together into increasingly larger assemblies for the realization of the bulk three-dimensional (3-D) crystal. The unique properties of many of these 2-D materials make them highly sought out candidates for advancing conventional …

Effects Of Air And Other Gases In The Stabilization Process Of The Superprotonic Phase Of Cesium Dihydrogen Phosphate Within A Hermetically Sealed Chamber, Israel Martinez

Open Access Theses & Dissertations

The solid acid CsH2PO4 (CDP), exhibits a sudden increase in its proton conductivity as it’s heated above a certain temperature (around T~235oC), which makes it a very attractive candidate to be used as an electrolyte in intermediate temperature fuel cells. Unfortunately, at these temperatures the sample is not stable, as starts to dehydrate; which causes a dramatic drop in the proton conductivity over a short period of time (less than one hour). In order to inhibit, or at least delay, the dehydration process, the solid acid it’s put under a saturated water vapor atmosphere. Another method to stabilize the highly …

Magnetic And Catalytic Properties Of Transition Metal Doped Mos2 Nanocrystals, Luis Martinez

Open Access Theses & Dissertations

Magnetism and catalytic activity of nanoscale layered two-dimensional (2D) transition metal dichalcogenides (TMDs) have gained an increasing research interest in the recent past. To broaden the current knowledge and understanding on this subject, in this work, together with my collaborators, I study the magnetic and electrocatalytic properties of hydrothermally grown pristine and transition metal doped (10% of Co, Ni, Fe and Mn) 2H-MoS2 nanosheets/nanocrystals (NCs), with the particle size of 25-30 nm. A broad range of experimental measurements such as x-ray diffraction, transmission electron microscopy, x-ray photo absorption spectroscopy, Raman spectroscopy, magnetic, catalytic and electron spin resonance have been employed …

Solvent And Concentration Effects Governing The Hierarchical Organization Of Asphaltenes: A Small-Angle X-Ray Scattering Study, Hasan Rejoanur Rahman

Open Access Theses & Dissertations

Asphaltenes are a group of planar molecules found in crude oil and are prone to aggregation which often causes blockage of pipes along the oil production stream resulting a huge economic downside. In an effort to understand the hierarchical organization of asphaltene in different solvents and concentrations, the solution structure of various asphaltene solutions were studied using small-angle x-ray scattering (SAXS). Solvents were chosen based on miscibility maps. Such maps are generated on the critical value of the solubility parameter difference between asphaltenes or asphaltene components, and a range of solvents. The critical factors that affect asphaltene and asphaltene component …

Tribological Characterization Of Ti-Based Alloys For Biomedical Applications In Simulated Body Fluid, Edgar Reyes

Open Access Theses & Dissertations

Tribology is a terminology introduced in the 1960's and it is a study that relates to the investigation of the damage of materials. Titanium, as a material used for a wide range of application, it has been brought to the attention of researchers some characteristics such as its much lower density if compared to steel, its capability as an alloying agent with an amount of metals to enhance physical and mechanical properties, to name just a few characteristics. This paper will discuss the performance on tribology behavior in two different Titanium alloys. These Titanium alloys are Ti-6Al-4V (Ti64), and Ti-24Nb-4Zr-8Sn …

Tungsten Doping Induced Superior Mechanical Properties Of Hafnium Oxide For Energy Applications, Ann Marie Uribe

Open Access Theses & Dissertations

Hafnium oxide, or hafnia, is a high temperature refractory material with good electrical, chemical, optical, and thermodynamic properties. The effects of dopants have been widely studied, especially after the discovery of ferroelectricity induced in hafnia thin films. While attractive and used in the opto-electronic, memory devices, and semiconductor industries, there is a lack in the literature on enhancing the mechanical properties of hafnium oxide, specifically through doping it with tungsten, another material of interest particularly for future high temperature device applications. Thus, this work aimed to grow hafnia thin films doped with varying amounts of tungsten. The samples were grown …

Evaluation Of Large Area Additively Manufactured Fiber Reinforced Acrylonitrile Butadiene Styrene (Abs), Kevin Schnittker

Open Access Theses & Dissertations

To enable the advancement of large-scale additive manufacturing processes, it is necessary to establish and standardize methodologies to characterize the mechanical properties of printed test coupons. Due to the large size of the print beads, conventional test standards are inadequate. The focus of this study was to determine the feasibility of using Digital image correlation (DIC) technology as a key enabler for robust data collection of strain measurements of large 3D printed parts. To incorporate the DIC measurements, a novel method was developed to prepare large 20 wt.% glass filled ABS test coupons for adequate contrast. Through this technique, Poisson's …

Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, Justin K. Thompson

Theses and Dissertations--Physics and Astronomy

Complex-oxides have seen an enormous amount of attention in the realm of Condensed Matter Physics and Materials Science/Engineering over the last several decades. Their ability to host a wide variety of novel physical properties has even caused them to be exploited commercially as dielectric, metallic and magnetic materials. Indeed, since the discovery of high temperature superconductivity in the “Cuprates” in the late 1980’s there has been an explosion of activity involving complex-oxides. Further, as the experimental techniques and equipment for fabricating thin films and heterostructures of these materials has improved over the last several decades, the search for new and …

Hydrophobicity Of Low Temperature Vibrating Surfaces, Christian Fergusson

Theses and Dissertations

This study proposes a method to enhance the anti-icing capabilities of superhydrophobic surfaces by utilizing vibration to further reduce contact time of an impacting droplet in addition to keeping the droplet in the Cassie-Baxter regime, where surface adhesion is lower than the opposing Wenzel regime. We tested this with two methods: by investigating the effects of vibration normal to the plane of a superhydrophobic surface being impacted by water droplets in a room temperature environment, with the surface horizontal in a room temperature environment and tiled in a subzero degree environment. The amplitude and frequency of the vibration were varied …

Liquid Interaction With Non-Wettable Surfaces Structured With Macroscopic Ridges, Mehran Abolghasemibizaki

Theses and Dissertations

Self-cleaning, anti-corrosion, anti-icing, dropwise-condensation, and drag-reduction are some applications in which superhydrophobic surfaces are implemented. To date, all the studies associated with superhydrophobic surfaces have been dedicated to understanding the liquid interaction with surfaces that are macroscopically smooth. The current study investigates the solid-liquid interaction of such surfaces which are fully decorated with macroscopic ridges (ribbed surfaces). In particular, the drop motion and impact on our newly designed non-wettable ribbed surface have been investigated in this work. Our experimental investigations have shown that liquid drops move faster on the ribbed surfaces due to lower friction induced by such a surface …

Consuming Digital Debris In The Plasticene, Stephen R. Parks

Theses and Dissertations

Claims of customization and control by socio-technical industries are altering the role of consumer and producer. These narratives are often misleading attempts to engage consumers with new forms of technology. By addressing capitalist intent, material, and the reproduction limits of 3-D printed objects’, I observe the aspirational promise of becoming a producer of my own belongings through new networks of production. I am interested in gaining a better understanding of the data consumed that perpetuates hyper-consumptive tendencies for new technological apparatuses. My role as a designer focuses on the resolution of not only the surface of the object through 3-D …

Influence Of Atmospheric Clearness On Pdlc Switchable Glazing Transmission, Aritra Ghosh, Brian Norton, Tapas K. Mallick

Articles

Electrically activated switchable polymer dispersed liquid crystal (PDLC) is suitable for adaptive windows. A particular type requires 20V to become 71% transparent while in the absence of power it is 27% transparent. Glazing transmission changes with light incident angle. As the clearness of a sky changes the fraction changes alter of direct insolation (that has an azimuthally changing incident) and diffuse insolation (that has a largely constant incident). Thus, the effective overall incident angle determining the glazing transmittance also changes. In this work for the first time, the variation of PDLC glazing transmission with clearness index has been investigated.

Effect Of Thickness On The Structure And Corrosion Performance Of Sputtered Ce-Al-O Coatings On Al 2024-T3 Alloy Substrates, Yuanyuan Liu, Jiamu Huang, Lilu Qin, James B. Claypool, Matthew J. O'Keefe, Yiming Jiang

Materials Science and Engineering Faculty Research & Creative Works

Ce-Al-O coatings with thicknesses between ca. 136 nm and 1094 nm were deposited on Al 2024-T3 alloy substrates using magnetron co-sputtering of independent Al and CeO2 targets. The Ce-Al-O coatings with thicknesses from ca. 136 nm to 490 nm were compact, dense, and did not have distinct X-ray diffraction peaks. The ca. 1094 nm thick Ce-Al-O coating exhibited a columnar-textured outer layer ∼700 nm thick and a dense, ∼390 nm thick inner layer. X-ray photoelectron spectroscopy analysis revealed that the Ce-Al-O coatings contained Ce (III) species, and that the Al/Ce atomic ratio decreased with increasing coating thickness. Electrochemical corrosion data …

An Energy-Based Approach To Assess And Predict Erosive Airfoil Defouling, Arthur Rudek, Thomas-Alexander Zitzmann, Geral Russ, Barry Duignan

Articles

A dynamic indentation experiment is presented for assessment of the adhesive behavior of a range of coatings in erosive defouling of commercial aircraft engines using CO2 dry-ice. A series of experiments is presented in which particles made from a reference material (polyoxymethylene – POM) and from CO2 dry-ice are made to impact compressor airfoils under a range of impact angle and velocity conditions. The airfoils investigated are coated with an indicator material (PTFE), which is typically used to visualise the defouling effect in large scale compressor defouling experiments. In addition, fouled compressor airfoils taken from service and coated with a …

Sand Distribution Effect On Three Dimensional Printed Sand Properties, Kip Woods

Dissertations and Theses @ UNI

The purpose of this study was to assess the performance characteristics of commercially available round grain silica sand for the use in three-dimensional sand printers. Two different average diameters were selected to examine the effects of screen distribution on printing performance; these diameters were 57-grain fineness number (GFN) and 70 GFN. These sands were a high purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates.

The resin system utilized in this investigation was a commercially available Furan resin system. Two test specimens were used in this study the American Foundry Society (AFS) tensile …