Materials Science and Engineering Commons^™

Infrared Transmitting Glasses With High Glass Transition Temperatures, Steve W. Martin

Iowa State University Patents

A chalcogenide glass capable of infrared transmission which is either sulfur, selenium or tellurium based and consists of compositions of the formula MX+M.sub.2 'X.sub.3 +SiX.sub.2, wherein M is one of the metals calcium, strontium, barium, zinc and lead, and M' is either aluminum or gallium and X is either sulfur, selenium or tellurium. Aluminum or gallium chalcogenide acts to increase the covalent bonding network structure of the glass with the result being that excellent high temperature 8-14 micron IR transmitting glasses with transition temperatures above 500C are prepared.

Ptsa Doped Conducting Graphene/Polyaniline Nanocomposite Fibers: Thermoelectric Behavior And Electrode Analysis, Mohammad Mansoob Khan Dr, M. O. Ansari, S. A. Ansari, M. I. Amal, J Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Highly conducting graphene/polyaniline (GN@Pani) nanocomposite was prepared by the in-situ oxidative polymerization of aniline in the presence of GN and the surfactant, cetyltrimethylammonium bromide (CTAB). The micellar structure of CTAB assisted both, the formation of GN@Pani tubules and the dispersion of GN. Sheet-like GN was distributed uniformly in the Pani matrix, leading to high electrical conductivity because of the π-π interactions between Pani and GN. Studies of the thermoelectrical behavior using isothermal and cyclic aging techniques showed that GN@Pani possessed a high combination of electrical conductivity and thermal stability, even beyond 150°C. GN@Pani was ...

Growth, Characterization And Simulation Of Inas Quantum Wires On Vicinal Substrates, Andrew Scullion

Open Access Dissertations and Theses

The heteroepitaxial growth of InAs self-assembled quantum wires on vicinal substrates is investigated. InGaAlAs lattice-matched to InP was first deposited onto an InP(001) substrate with and without a 0.9 degree off-cut toward the (110) direction, followed by the deposition of a strained layer of InAs. Dense InAs quantum wires were successfully grown on both nominally flat and vicinal substrates in order to observe the effect of the presence of atomic steps. The off-cut angle was chosen based on the wire spacing on a flat substrate to serve as a template for their nucleation and improve their size distribution ...

An Investigation Into The Role Of Energy And Symmetry At Epitaxial Interfaces, Gabriel A. Devenyi

Open Access Dissertations and Theses

Epitaxy is a key technological process for the production of thin films and nanostructures for electronic and optoelectronic devices. The epitaxial process has been traditionally studied through the lens of lattice-matched and chemically similar material systems, specifically the III-V quaternary material systems. This work investigates the role energy and symmetry play at epitaxial interfaces for cases far different than those of typical epitaxy. In the realm of energy, the impact of chemically dissimilar epitaxial interfaces was investigated, specifically between semiconductors and oxides, noble metals and oxides, and polar-on-nonpolar epitaxy. For symmetry at epitaxial interfaces, the role of symmetry breaking, through ...

Asymmetrical I-V Curves From A Symmetrical Devices Structure Of Organic Photovoltaics, Shangzhi Chen

Open Access Dissertations and Theses

The energy diagram for organic photovoltaics (OPV), involving the bulk heterojunction (BHJ), on which the device analysis is usually based, has long been a subject of debate. The widely used Metal-insulator-Metal model and P-type Schottky Junction model, both of which are based on inappropriate assumptions, could be incorrect to explain the working principle of BHJ OPV.

To further explore the controversy, we start the investigation from the opposite direction, to the usually asymmetrical OPV, involving electron and hole passages, by introducing a pair of symmetric electrodes to a BHJ, to form a completely symmetrical device structure, which, in theory, would ...

Substrates Manipulation And Epitaxial Growth Of Gallium Nitride Thin Films, Huaxiang Shen

Open Access Dissertations and Theses

Light emitting diode (LED)-based solid state displays (SSD) have attracted growing interest due to their advantages in terms of contrast ratio, brightness, viewing angle, and response time compared to liquid crystal displays. GaN based III-nitride thin film materials are suitable materials for SSD due to their wide and tunable bandgaps. However, the large size and costly manufacturing process of commercially available GaN-based LED chips limit the potential uses of LEDs as the pixels of SSD.

In this work, tiny single crystal beta-phase (111) oriented SiC whiskers 2 microns in diameter and 18 microns in length are proposed as the ...

Surface Analysis Of Materials For Direct Wafer Bonding, Arif Ul Alam

Open Access Dissertations and Theses

Surface preparation and its exposure to different processing conditions is a key step in heterogeneous integration of electronics, photonics, fluidics and/or mechanical components for More-than-Moore applications. Therefore, it is critical to understand how various processing and environmental conditions affect the surface properties of bonding substrates. In this thesis, the effects of oxygen reactive-ion etching (O₂ RIE) plasma followed by storage in ambient and 98% relative humidity on some key surface properties such as roughness, water contact angle, hardness, and the elemental and compositional states of three materials – silicon (Si), silicon dioxide (SiO₂) and glass – are investigated to ...

Heat-Affected Zone Softening Kinetics In Dual-Phase And Martensitic Steels, Elliot Biro

Open Access Dissertations and Theses

Advanced high strength steels, such as dual-phase and martensitic steels, are increasingly being used by automakers to decrease the thickness of steel sheet used in parts without sacrificing part strength. When welded, the martensite within the dual-phase and martensitic steel microstructures tempers, reducing the heat-affected zone (HAZ) hardness compared to the base material, locally reducing strength. This process is known as HAZ softening. HAZ softening has been well studied; however, the kinetics of this process has not been quantified and the processes responsible for HAZ softening have not been examined. This thesis investigated both of these topics.

HAZ softening was ...

Post-Failure Capacity Of Built-Up Steel Members, Matthew H. Hebdon

Purdue Road School

Mechanically fastened built-up steel members have long been known to possess internal member redundancy and, as a result, multiple load paths which can be exploited to increase their functional life. Internal redundancy provides the ability to resist total member failure in the event of a fracture of an individual component. However, there is little experimental data in the literature regarding post-fracture capacity in terms of strength and subsequent fatigue life. The experimental study currently underway will provide needed information on parameters that affect the ability of built- up members to arrest a fracture as well as the available remaining fatigue ...

Post-Fracture Capacity Of Railroad Flat Car Bridges, Teresa L. Washeleski

Purdue Road School

Railroad flatcars (RRFCs) are a convenient option to replace existing deteriorating bridge structures on low-volume roads. They are typically used as the bridge superstructure by placing two or more flatcars side-by-side to achieve the desired bridge width. Utilizing RRFCs as a bridge allows for rapid construction and greater cost savings compared to traditional practices. These benefits make them an attractive solution for rural communities in Indiana, as well as other states.

Uncertainty remains about the response under higher loads than could be easily achieved in the field and the level of redundancy of railroad flatcar bridges. Using RRFCs as bridges ...

Zno Nanosheet Arrays Constructed On Weaved Titanium Wire For Cds-Sensitized Solar Cells, Cuncun Wu, Lin Wei, Yitan Li, Chang Liu, Jun Jiao, Yanxue Chen, Liangmo Mei

Mechanical and Materials Engineering Faculty Publications and Presentations

Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically. The best light-to-electricity conversion efficiency was obtained to be 2.17% under 100 mW/cm/cm² illumination, and a remarkable shortcircuit photocurrent density of approximately 20.1 mA/cm² was recorded, which could attribute to the relatively direct pathways for transportation of electrons ...

Cds Quantum Dot-Sensitized Solar Cells Based On Nano-Branched Tio2 Arrays, Chang Liu, Yitan Li, Lin Wei, Cuncun Wu, Yanxue Chen, Liangmo Mei, Jun Jiao

Mechanical and Materials Engineering Faculty Publications and Presentations

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for ...

Identification Of Silver And Palladium In Irradiated Triso Coated Particles Of The Agr-1 Experiment, I. J. Van Rooyen, T. M. Lillo, Y. Q. Wu

Materials Science and Engineering Faculty Publications and Presentations

Evidence of the release of certain metallic fission products through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at the Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes.

Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy-Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM ...

Chapters 5 And 6, Eng-Poh Ng Dr.

Eng-Poh Ng

No abstract provided.

Mixed Culture Electrochemically Active Biofilms And Their Microscopic And Spectroelectrochemical Studies, Mohammad Mansoob Khan Dr, S. A. Ansari, J. H. Lee, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Mixed culture electrochemically active biofilms (EABs) were developed on carbon paper using a sludge with mixed culture bacteria for microscopic and pectroelectrochemical studies because a naturally mixed culture bacterial strain is more applicable than a pure culture strain. EAB development was confirmed by microbial fuel cells (MFCs) by obtaining a constant increase in potential (∼0.36 V). Microscopic and spectroscopic studies showed that a mixed culture EABs formed on the support. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, indicated that the EABs could be source of electrons and used effectively ...

History Of Innovation In Extractive Metallurgy, Fathi Habashi

Fathi Habashi

People learned melting of ores to get metals since ancient times but the use of aqueous solutions for this purpose was introduced relatively recently in the Middle Ages. The most recent technology, however, came when electric current became available on commercial scale towards the middle of the nineteenth century. The present article records in general terms the development in pyro- , hydro-, and electrometallurgy

Enhanced Thermoelectric Performance And Ammonia Sensing Properties Of Sulfonated Polyaniline/Graphene Thin Films,, M. O. Ansari, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. I. Amal, M H. Cho

Dr. Mohammad Mansoob Khan

Highly conducting nanocomposite film of polyaniline (Pani) with graphene (GN) was prepared by incorporating GN nanoplatelets in Pani matrix, followed by sulfonating it with fuming sulfuric acid. Sheet-like GN nanoplatelets were distributed uniformly in a Pani matrix, leading to high electrical conductivity due to π-π interaction between sulfonated Pani (s-Pani) and GN. Studies of the thermoelectrical behavior and ammonia-sensing behavior on GN@s-Pani showed high DC electrical conductivity retention under ageing conditions as well as excellent reproducible sensing response towards ammonia vapor in contrast to acid-protonated Pani.

Quantifying Reinforced Concrete Bridge Deck Deterioration Using Ground Penetrating Radar, Nicole Martino

Civil Engineering Dissertations

Bridge decks are deteriorating at an alarming rate due to corrosion of the reinforcing steel, requiring billions of dollars to repair and replace them. Furthermore, the techniques used to assess the decks don't provide enough quantitative information. In recent years, ground penetrating radar (GPR) has been used to quantify deterioration by comparing the rebar reflection amplitudes to technologies serving as ground truth, because there is not an available amplitude threshold to distinguish healthy from corroded areas using only GPR. The goal of this research is to understand the relationship between GPR and deck deterioration, and develop a model to ...

Highly Sensitive Tube-Topology Magnetoelectric Magnetic Sensors, Scott M. Gillette

Electrical Engineering Dissertations

Magnetoelectric (ME) composites have drawn increasing interest in recent years due to advancements in the technology resulting in enhanced ME coupling coefficients, stable room-temperature operation, sub-nanoTesla noise floor, low- and zero-biased operation, and fabrication of compact, miniaturized devices. Now, more than ever, practical use of ME devices in commercial magnetometry applications is feasible, while continued development of numerous other applications, such as voltage-tunable magnetic field generators, voltage-tunable inductors, and magnetically-tunable capacitors, bolster the overall usefulness of ME composites as a valuable technology. This dissertation focuses on development and characterization of tube-topology ME composites as magnetic field sensors. The novel topology ...

Effect Of Er Doping On The Structural And Magnetic Properties Of Cobalt-Ferrite, Sateesh Prathapani, M. Vinitha, Tanjore V. Jayaraman, D. Das

Mechanical & Materials Engineering Faculty Publications

Nanocrystalline particulates of Er doped cobalt-ferrites CoFe_(2–x)Er_xO₄ (0 ≤ x ≤ 0.04), were synthesized, using sol-gel assisted autocombustion method. Co-, Fe-, and Er- nitrates were the oxidizers, and malic acid served as a fuel and chelating agent. Calcination (400–600 °C for 4h) of the precursor powders was followed by sintering (1000 °C for 4 h) and structural and magnetic characterization. X-ray diffraction confirmed the formation of single phase of spinel for the compositions x = 0, 0.01, and 0.02; and for higher compositions an additional orthoferrite phase formed along with the spinel phase ...