Materials Science and Engineering Commons^™

Comparing Structure-Property Evolution For Pm-Hip And Forged Alloy 625 Irradiated With Neutrons To 1 Dpa, Caleb Clement, Sowmya Panuganti, Patrick H. Warren, Yangyang Zhao, Yu Lu, Katelyn Wheeler, David Frazer, Donna P. Guillen, David W. Gandy, Janelle P. Wharry

Materials Science and Engineering Faculty Publications and Presentations

The nuclear power industry has growing interest in qualifying powder metallurgy with hot isostatic pressing (PM-HIP) to replace traditional alloy fabrication methods for reactor structural components. But there is little known about the response of PM-HIP alloys to reactor conditions. This study directly compares the response of PM-HIP to forged Ni-base Alloy 625 under neutron irradiation doses ∼0.5–1 displacements per atom (dpa) at temperatures ranging ∼321–385 °C. Post-irradiation examination involves microstructure characterization, ASTM E8 uniaxial tensile testing, and fractography. Up through 1 dpa, PM-HIP Alloy 625 appears more resistant to irradiation-induced cavity nucleation than its forged counterpart, and consequently experiences …

Perturbative Theoretical Model Of Electronic Transient Circular Dichroism Spectroscopy Of Molecular Aggregates, Paul C. Arpin, Daniel B. Turner

Materials Science and Engineering Faculty Publications and Presentations

A chiral analog of transient absorption spectroscopy, transient circular dichroism (TCD) spectroscopy is an emerging time-resolved method. Both spectroscopic methods can probe the electronic transitions of a sample, and TCD is additionally sensitive to the dynamic aspects of chirality, such as those induced by molecular excitons. Here, we develop a theoretical description of TCD for electronic multi-level models in which the pump pulse is linearly polarized and probe pulse is alternately left- and right-circularly polarized. We derive effective response functions analogous to those often used to describe other four-wave mixing methods and then simulate and analyze TCD spectra for three …

Tunable Electronic Structure Via Dna-Templated Heteroaggregates Of Two Distinct Cyanine Dyes, Jonathan S. Huff, Matthew S. Barclay, Azhad U. Chowdhury, Lance K. Patten, Simon K. Roy, Aaron Sup, Austin Biaggne, Lan Li, Jeunghoon Lee, Paul H. Davis, Bernard Yurke, William B. Knowlton, Daniel B. Turner, Ryan D. Pensack

Materials Science and Engineering Faculty Publications and Presentations

Molecular excitons are useful for applications in light harvesting, organic optoelectronics, and nanoscale computing. Electronic energy transfer (EET) is a process central to the function of devices based on molecular excitons. Achieving EET with a high quantum efficiency is a common obstacle to excitonic devices, often owing to the lack of donor and acceptor molecules that exhibit favorable spectral overlap. EET quantum efficiencies may be substantially improved through the use of heteroaggregates─aggregates of chemically distinct dyes─rather than individual dyes as energy relay units. However, controlling the assembly of heteroaggregates remains a significant challenge. Here, we use DNA Holliday junctions to …

Molecular Dynamics Simulations Of Cyanine Dimers Attached To Dna Holliday Junctions, Austin Biaggne, Young C. Kim, Joseph S. Melinger, William B. Knowlton, Bernard Yurke, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

Dye aggregates and their excitonic properties are of interest for their applications to organic photovoltaics, non-linear optics, and quantum information systems. DNA scaffolding has been shown to be effective at promoting the aggregation of dyes in a controllable manner. Specifically, isolated DNA Holliday junctions have been used to achieve strongly coupled cyanine dye dimers. However, the structural properties of the dimers and the DNA, as well as the role of Holliday junction isomerization are not fully understood. To study the dynamics of cyanine dimers in DNA, molecular dynamics simulations were carried out for adjacent and transverse dimers attached to Holliday …

Zinc–Acetate–Amine Complexes As Precursors To Zno And The Effect Of The Amine On Nanoparticle Morphology, Size, And Photocatalytic Activity, Josh Eixenberger, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

Zinc oxide is an environmentally friendly and readily synthesized semiconductor with many industrial applications. ZnO powders were prepared by alkali precipitation using different [Zn(acetate)₂(amine)_x] compounds to alter the particle size and aspect ratio. Slow precipitations from 95 °C solutions produced micron-scale particles with morphologies of hexagonal plates, rods, and needles, depending on the precursor used. Powders prepared at 65 °C with rapid precipitation yielded particles with minimal morphology differences, but particle size was dependent on the precursor used. The smallest particles were produced using precursors that yielded crystals with low aspect ratios during high-temperature synthesis. Particles …

Irradiation-Induced Amorphous-To-Crystalline Phase Transformations In Ceramic Materials, Cyrus Koroni, Tristan Olsen, Janelle P. Wharry, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Amorphous ceramics are a unique class of materials with unusual properties and functionalities. While these materials are known to crystallize when subjected to thermal annealing, they have sometimes been observed to crystallize athermally when exposed to extreme irradiation environments. Because irradiation is almost universally understood to introduce disorder into materials, these observations of irradiation-induced ordering or crystallization are unusual and may partially explain the limited research into this phenomenon. However, the archival literature presents a growing body of evidence of these irradiation-induced amorphous-to-crystalline (a-to-c) phase transformations in ceramics. In this perspective, the summary and review of examples from the literature …

Extending The Low-Temperature Operation Of Sodium Metal Batteries Combining Linear And Cyclic Ether-Based Electrolyte Solutions, Haoyu Zhu, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Nonaqueous sodium-based batteries are ideal candidates for the next generation of electrochemical energy storage devices. However, despite the promising performance at ambient temperature, their low-temperature (e.g., < 0 °C) operation is detrimentally affected by the increase in the electrolyte resistance and solid electrolyte interphase (SEI) instability. Here, to circumvent these issues, we propose specific electrolyte formulations comprising linear and cyclic ether-based solvents and sodium trifluoromethanesulfonate salt that are thermally stable down to −150 °C and enable the formation of a stable SEI at low temperatures. When tested in the Na||Na coin cell configuration, the low-temperature electrolytes enable long-term cycling down to −80 °C. Via ex situ physicochemical (e.g., X-ray photoelectron spectroscopy, cryogenic transmission electron microscopy and atomic force microscopy) electrode measurements and density functional theory calculations, we investigate the mechanisms responsible for efficient low-temperature electrochemical performance. We also report the assembly and testing between −20 °C and −60 °C of full Na||Na₃V₂(PO₄)₃ coin cells. The cell tested at −40 °C shows an initial discharge capacity of 68 mAh g⁻¹ with a capacity retention of approximately 94% after 100 cycles at 22 mA g⁻¹.

Study As Form-Of-Life: Meditations On Schooling, Enjoyment, And The Inoperative Life, Bryan K. Weeks

Boise State University Theses and Dissertations

The aim of this thesis is to explore what potential that the concept of 'inoperativity' has in the philosophy and theory of education. I will discuss the method of critique used which aims to think through the problems in existing theory rather than discard good thinking when problems are found. The strengths and weaknesses of deschooling and democratic approaches will be at the center of this critique. As a response to the weaknesses of both, the philosophy of Emmanuel Levinas, focusing on the way that interiority and enjoyment are essential concepts for the philosophy of education, as well as Giorgio …

Solution Synthesis And Additive Manufacturing Of Bismuth Telluride Nanoflakes For Flexible Energy Harvesting, Ariel E. Weltner

Boise State University Theses and Dissertations

Flexible thermoelectric generators (TEGs) are energy harvesting devices which convert temperature differences into electrical power. These devices require no moving parts and offer silent and autonomous operation. The variety of suitable materials covering a broad range of operating temperatures positions TEGs as a promising renewable energy source using waste heat recovery, especially for space and microgravity applications. Conventional manufacturing of flexible electronic and thermoelectric devices requires complicated and relatively expensive processing, which limits the capabilities of in-space manufacturing. Additive manufacturing (AM) expands the use of flexible electronics to new surfaces, applications, and recently, low gravity conditions. Plasma jet printing (PJP) …

Open-Source Workflows For Reproducible Molecular Simulation, Jenny W. Fothergill

Boise State University Theses and Dissertations

We apply molecular simulation to predict the equilibrium structure of organic molecular aggregates and how these structures determine material properties, with a focus on software engineering practices for ensuring correctness. Because simulations are implemented in software, there is potential for authentic scientific reproducibility in such work: An entire experimental apparatus (codebase) can be given to another investigator who should be able to use the same processes to find the same answers. Yet in practice, there are many barriers which stand in the way of reproducible molecular simulations that we address through automation, generalization, and software packaging. Collaboration on and application …

Reproducible Prediction Of Organic Semiconductor Properties Through Open Source Software Development, James Rushing

Boise State University Theses and Dissertations

Semiconducting materials made from carbon-based molecules are potential replacements for inorganic semiconductors, but with lower costs of processing. Devices made from organic semiconductors can be produced at scale by inkjet printing and roll-to-roll manufacturing of these molecules in solution or melt phases. The efficiency of these organic devices is dependent on the structure of the active layer, so controlling the morphology of organic molecules through self-assembly during manufacturing is a key challenge to realizing their utility. Molecular self-assembly depends on the chemical structure of the molecules, how key moieties interact with each other and with any solvent present, and the …

Removal And Recovery Of Ammonia From Simulated Wastewater Using Ti3C2TX Mxene In Flow Electrode Capacitive Deionization, Naqsh E. Mansoor, Luis A. Diaz, Christopher E. Shuck, Yury Gogotsi, Tedd E. Lister, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

Flowing electrode capacitive deionization systems (FE-CDI) have recently garnered attention because of their ability to prevent cross contamination and operate in uninterrupted cycles ad infinitum. Typically, FE-CDI electrodes suffer from low conductivity, reducing deionization performance. Utilization of higher mass loadings to combat this leads to poor rheological properties. Herein, Ti₃C₂T_x MXene was introduced as 1 mg mL⁻¹ slurry electrodes in an FE-CDI system for the removal and recovery of ammonia from simulated agricultural wastewater. The electrode performance was evaluated by operating the FE-CDI system with a feed solution of 500 mg L⁻¹ NH …

Oblique Packing And Tunable Excitonic Coupling In Dna-Templated Squaraine Rotaxane Dimer Aggregates, Matthew S. Barclay, Christopher K. Wilson, Simon K. Roy, Olga A. Mass, Azhad U. Chowdhury, Jonathan S. Huff, Daniel B. Turner, Paul H. Davis, Bernard Yurke, William B. Knowlton, Jeunghoon Lee, Ryan D. Pensack

Materials Science and Engineering Faculty Publications and Presentations

When molecules are aggregated such that their excited states form delocalized excitons, their spatial arrangement, or packing, can be coarsely controlled by templating and finely controlled by chemical substitution; however, challenges remain in controlling their packing on intermediate length scales. Here, we use an approach based on mechanically interlocked molecules to promote an elusive oblique packing arrangement in a series of three squaraine rotaxane dimers. We template the squaraine rotaxane dimers using DNA and observe two excitonically split bands of near-equal intensity in their absorption spectra – a distinct signature of oblique packing, validated by theoretical modeling of the experimental …

Electrochemically Induced Amorphous-To-Rock-Salt Phase Transformation In Niobium Oxide Electrode For Li-Ion Batteries, Pete Barnes, Yunxing Zuo, Kiev Dixon, Dewen Hou, Sungsik Lee, Zhiyuan Ma, Justin G. Connell, Hua Zhou, Changjian Deng, Kassiopeia Smith, Eric Gabriel, Yuzi Liu, Olivia O. Maryon, Paul H. Davis, Haoyu Zhu, Yingge Du, Ji Qi, Zhuoying Zhu, Chi Chen, Zihua Zhu, Yadong Zhou, Paul J. Simmonds, Ariel E. Briggs, Darin Schwartz, Shyue Ping Ong, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Intercalation-type metal oxides are promising negative electrode materials for safe rechargeable lithium-ion batteries due to the reduced risk of Li plating at low voltages. Nevertheless, their lower energy and power density along with cycling instability remain bottlenecks for their implementation, especially for fast-charging applications. Here, we report a nanostructured rock-salt Nb₂O₅ electrode formed through an amorphous-to-crystalline transformation during repeated electrochemical cycling with Li⁺. This electrode can reversibly cycle three lithiums per Nb₂O₅, corresponding to a capacity of 269 mAh g⁻¹ at 20 mA g⁻¹, and retains a capacity …

Characterizing Mode Anharmonicity And Huang–Rhys Factors Using Models Of Femtosecond Coherence Spectra, Matthew S. Barclay, Jonathan S. Huff, Ryan D. Pensack, Paul H. Davis, William B. Knowlton, Bernard Yurke, Jacob C. Dean, Paul C. Arpin, Daniel B. Turner

Materials Science and Engineering Faculty Publications and Presentations

Femtosecond laser pulses readily produce coherent quantum beats in transient–absorption spectra. These oscillatory signals often arise from molecular vibrations and therefore may contain information about the excited-state potential energy surface near the Franck–Condon region. Here, by fitting the measured spectra of two laser dyes to microscopic models of femtosecond coherence spectra (FCS) arising from molecular vibrations, we classify coherent quantum-beat signals as fundamentals or overtones and quantify their Huang–Rhys factors and anharmonicity values. We discuss the extracted Huang–Rhys factors in the context of quantum-chemical computations. This work solidifies the use of FCS for analysis of coherent quantum beats arising from …

Data-Driven And Multiscale Modeling Of Dna-Templated Dye Aggregates, Austin Biaggne, Lawrence Spear, German Barcenas, Maia Ketteridge, William B. Knowlton, Bernard Yurke, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

Dye aggregates are of interest for excitonic applications, including biomedical imaging, organic photovoltaics, and quantum information systems. Dyes with large transition dipole moments (μ) are necessary to optimize coupling within dye aggregates. Extinction coefficients (ε) can be used to determine the μ of dyes, and so dyes with a large ε (>150,000 M⁻¹) should be engineered or identified. However, dye properties leading to a large ε are not fully understood, and low-throughput methods of dye screening, such as experimental measurements or density functional theory (DFT) calculations, can be time-consuming. In order to screen large datasets of molecules …

Additive Manufacturing Of Sensors For Extreme Environments, Kiyo Tiffany Fujimoto

Boise State University Theses and Dissertations

Advanced manufacturing based direct-write technologies have emerged as the predominant enabler for the fabrication of active and passive sensors for use in harsh operating environments. The ability to directly write and integrate electronic components onto physical packaging can be achieved with additive manufacturing (AM) methods such as direct write technologies (DWT) which include aerosol jet printing (AJP), Ink Jet Printing (IJP), Plasma Jet Printing (PJP), and Micro-Dispense Printing (MDP). In this work, we investigate the use of these methods to accelerate, modernize, and enhance the functionality of sensors and instrumentation to achieve the goal of improving the safety and efficiency …

Towards Improving The Properties And Furthering Acceptance Of Advanced Technology Nuclear Fuels, Jennifer K. Watkins

Boise State University Theses and Dissertations

To avoid detrimental environmental impacts from climate change, the world community needs to push for the use of clean energy technologies. Development of proposed advanced technology nuclear fuels supports efforts to ensure nuclear energy is included as a non-carbon emitting source of electricity generation. Advanced technology nuclear fuels, also referred to as accident tolerant fuels (ATFs), have received renewed interest for use in the current nuclear reactor fleet as well as in advanced reactor technologies due to their high uranium loading, desirable thermophysical properties, and performance under irradiation as compared to the benchmark oxide fuel. A limiting consideration for the …

Multiphase Layered Transition Metal Oxide Positive Electrodes For Sodium Ion Batteries, Eric Gabriel, Dewen Hou, Eungje Lee, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Multiphase layered transition metal oxides (LTMOs) for sodium ion battery (SIB) positive electrodes with phase interfaces across multiple length scales are a promising avenue toward practical, high-performance SIBs. Combinations of phases can complement each other's strengths and mitigate their weaknesses if their interfaces are carefully controlled. Intra- and interparticle phase interactions from nanoscale to macroscale must be carefully tuned to generate distinct effects on properties and performance. An informed design strategy must be paired with relevant synthesis techniques and complemented by spatially resolved characterization tools to manipulate different length scales and interfaces. This review examines the design, synthesis, and characterization …

Electrochemical Impedance Spectroscopy Of Zirconium Oxidation For In-Situ Nuclear Sensing Applications, Michael Andrew Reynolds

Boise State University Theses and Dissertations

To meet the ever-growing energy demands of the modern world, alternative forms of producing power are necessary, and the field of nuclear engineering holds promise to answer this call. Nuclear fuel cladding in light water reactors (LWRs) currently draws a large amount of attention from scientists and researchers, as it provides many challenges to design around. Since the 1950s, zirconium and its protective oxide layer have been utilized as an effective material for the task, possessing good mechanical strengths, high corrosion resistance, and a low neutron absorption cross section. Despite these beneficial properties, however, fuel cladding remains vulnerable to several …

Quasi In-Situ Ebsd Analysis Of Twinning-Detwinning And Slip Behaviors In Textured Az31 Magnesium Alloy Subjected To Compressive-Tensile Loading, Yuzhi Zhu, Dewen Hou, Qizhen Li

Materials Science and Engineering Faculty Publications and Presentations

Twinning and detwinning behavior, together with slip behavior, are studied in a textured AZ31 magnesium alloy under compressive and tensile strains along the rolling direction (RD) after each interrupted mechanical test via quasi in-situ electron backscattered diffraction technique. The results show that twinning firstly takes place under the compressive strain along the RD. With the increasing compressive strain, {1012} tensile twins firstly nucleate, then propagate, and finally thicken. While under a reversed tensile strain along the RD, detwinning occurs. No nucleation happens during detwinning. Thus, tensile twins can detwin at lower tensile strain, followed by thinning, shortening, and vanishing. Slips …

Tuning Between Quenching And Energy Transfer In Dna-Templated Heterodimer Aggregates, Azhad U. Chowdhury, Jonathan S. Huff, Matthew S. Barclay, Lance K. Patten, Aaron Sup, Natalya Hallstrom, Jeunghoon Lee, Paul H. Davis, Daniel B. Turner, Bernard Yurke, William B. Knowlton, Ryan D. Pensack

Materials Science and Engineering Faculty Publications and Presentations

Molecular excitons, which propagate spatially via electronic energy transfer, are central to numerous applications including light harvesting, organic optoelectronics, and nanoscale computing; they may also benefit applications such as photothermal therapy and photoacoustic imaging through the local generation of heat via rapid excited-state quenching. Here we show how to tune between energy transfer and quenching for heterodimers of the same pair of cyanine dyes by altering their spatial configuration on a DNA template. We assemble “transverse” and “adjacent” heterodimers of Cy5 and Cy5.5 using DNA Holliday junctions. We find that the transverse heterodimers exhibit optical properties consistent with excitonically interacting …

Influence Of Hydrophobicity On Excitonic Coupling In Dna-Templated Indolenine Squaraine Dye Aggregates, Olga A. Mass, Christopher K. Wilson, German Barcenas, Lan Li, Bernard Yurke, William B. Knowlton, Ryan D. Pensack, Jeunghoon Lee

Materials Science and Engineering Faculty Publications and Presentations

Control over the strength of excitonic coupling in molecular dye aggregates is a substantial factor for the development of technologies such as light harvesting, optoelectronics, and quantum computing. According to the molecular exciton model, the strength of excitonic coupling is inversely proportional to the distance between dyes. Covalent DNA templating was proved to be a versatile tool to control dye spacing on a subnanometer scale. To further expand our ability to control photophysical properties of excitons, here, we investigated the influence of dye hydrophobicity on the strength of excitonic coupling in squaraine aggregates covalently templated by DNA Holliday Junction (DNA …

Special Topic On Materials And Devices For 5g Electronics, Nathan D. Orloff, Rick Ubic, Michael Lanagan

Materials Science and Engineering Faculty Publications and Presentations

Next generation communications are inspiring entirely new applications in education, healthcare, and transportation. These applications are only possible because of improvements in latency, data rates, and connectivity in the latest generation. Behind these improvements are new materials and devices that operate at much higher frequencies than ever before, a trend that is likely to continue.

Synergic Antitumor Effect Of Photodynamic Therapy And Chemotherapy Mediated By Nano Drug Delivery Systems, Mozhgan Aghajanzadeh, Mostafa Zamani, Fereshteh Rajabi Kouchi, Josh Eixenberger, Dorsa Shirini, David Estrada, Farhad Shirini

Materials Science and Engineering Faculty Publications and Presentations

This review provides a summary of recent progress in the development of different nano-platforms for the efficient synergistic effect between photodynamic therapy and chemotherapy. In particular, this review focuses on various methods in which photosensitizers and chemotherapeutic agents are co-delivered to the targeted tumor site. In many cases, the photosensitizers act as drug carriers, but this review, also covers different types of appropriate nanocarriers that aid in the delivery of photosensitizers to the tumor site. These nanocarriers include transition metal, silica and graphene-based materials, liposomes, dendrimers, polymers, metal–organic frameworks, nano emulsions, and biologically derived nanocarriers. Many studies have demonstrated various …

Exciton Delocalization In A Dna-Templated Organic Semiconductor Dimer Assembly, Xiao Wang, Ruojie Sha, William B. Knowlton, Nadrian C. Seeman, James W. Canary, Bernard Yurke

Materials Science and Engineering Faculty Publications and Presentations

A chiral dimer of an organic semiconductor was assembled from octaniline (octamer of polyaniline) conjugated to DNA. Facile reconfiguration between the monomer and dimer of octaniline–DNA was achieved. The geometry of the dimer and the exciton coupling between octaniline molecules in the assembly was studied both experimentally and theoretically. The octaniline dimer was readily switched between different electronic states by protonic doping and exhibited a Davydov splitting comparable to those previously reported for DNA–dye systems employing dyes with strong transition dipoles. This approach provides a possible platform for studying the fundamental properties of organic semiconductors with DNA-templated assemblies, which serve …

A Comparison Of Solid Electrolyte Interphase Formation And Evolution On Highly Oriented Pyrolytic And Disordered Graphite Negative Electrodes In Lithium-Ion Batteries, Haoyu Zhu, Joshua A. Russell, Zongtang Fang, Pete Barnes, Lan Li, Corey M. Efaw, Allison Muenzer, Jeremy May, Kailash Hamal, I. Francis Cheng, Paul H. Davis, Eric J. Dufek, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

The presence and stability of solid electrolyte interphase (SEI) on graphitic electrodes is vital to the performance of lithium-ion batteries (LIBs). However, the formation and evolution of SEI remain the least understood area in LIBs due to its dynamic nature, complexity in chemical composition, heterogeneity in morphology, as well as lack of reliable in situ/operando techniques for accurate characterization. In addition, chemical composition and morphology of SEI are not only affected by the choice of electrolyte, but also by the nature of the electrode surface. While introduction of defects into graphitic electrodes has promoted their electrochemical properties, how such structural …

Tensile-Strained Self-Assembly Of Ingaas On Inas(111)A, Kevin D. Vallejo, Trent A. Garrett, Carlos I. Cabrera, Baolai Liang, Kevin A. Grossklaus, Paul J. Simmonds

Materials Science and Engineering Faculty Publications and Presentations

We have determined a reproducible set of growth conditions for the self-assembly of tensile-strained In_1-xGa_xAs quantum dot (QD) nanostructures on (111)A surfaces. During molecular beam epitaxy, In_1-xGa_xAs islands form spontaneously on InAs(111)A when the Ga content x ≥ 50%. We analyze the structure and composition of InGaAs/InAs(111) samples using atomic force microscopy, transmission electron microscopy, and electron energy loss spectroscopy. We demonstrate control over the size and areal density of the islands as a function of In_1-xGa_xAs coverage, In_1-xGa_xAs composition, …

Dreams Of Molecular Beams: Indium Gallium Arsenide Tensile-Strained Quantum Dots And Advances Towards Dynamic Quantum Dots (Moleculare Radiorum Somnia: Indii Gallii Arsenicus Tensa Quanta Puncta Et Ad Dinamicae Quantae Puntae Progressus), Kevin Daniel Vallejo

Boise State University Theses and Dissertations

Through the operation of a molecular beam epitaxy (MBE) machine, I worked on developing the homoepitaxy of high quality InAs with a (111)A crystallographic orientation. By tuning substrate temperature, we obtained a transition from a 2D island growth mode to step- ow growth. Optimized MBE parameters (substrate temperature = 500 °C, growth rate = 0.12 ML/s and V/III ratio ⩾ 40) lead to growth of extremely smooth InAs(111)A films, free from hillocks and other 3D surface imperfections. We see a correlation between InAs surface smoothness and optical quality, as measured by photoluminescence spectroscopy. This work establishes InAs(111)A as a platform …

Structure And Kinetics Of Twin Boundaries In Shape Memory Alloys, Bibek Jung Karki

Boise State University Theses and Dissertations

Shape memory alloys (SMAs) are functional materials that recover from large strains without permanent deformation. In magnetic shape memory alloys (MSMAs), the reversible deformation is driven either magnetically or mechanically. Two underlying phenomena are responsible for the shape memory effect: (a) a diffusionless, martensitic transformation and (b) twinning in the martensite phase.

In MSMAs, the reversible plastic deformation occurs via twinning in the martensite phase, particularly via the movement of twinning disconnections (TDs) along the twin boundaries (TBs). A geometric algorithm called the classical model (CM) of deformation twinning describes operative twinning modes of a given crystal system. There are …