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Materials Science and Engineering Faculty Research & Creative Works

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Full-Text Articles in Materials Science and Engineering

Impact Of Symmetry On The Ferroelectric Properties Of Catio₃ Thin Films, Michael D. Biegalski, Liang Qiao, Yijia Gu, Apurva Mehta, Qian He, For Full List Of Authors, See Publisher's Website. Apr 2015

Impact Of Symmetry On The Ferroelectric Properties Of Catio₃ Thin Films, Michael D. Biegalski, Liang Qiao, Yijia Gu, Apurva Mehta, Qian He, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO3, through the careful control of the biaxial strain state and TiO6 octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO3 films grown on La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) and NdGaO3 (NGO) substrates experienced a 1.1% biaxial strain state …

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Producing High Strength Aluminum Alloy By Combination Of Equal Channel Angular Pressing And Bake Hardening, Hamid Alihosseini, Mohsen Asle Zaeem, Kamran Dehghani, Ghader Faraji Feb 2015

Producing High Strength Aluminum Alloy By Combination Of Equal Channel Angular Pressing And Bake Hardening, Hamid Alihosseini, Mohsen Asle Zaeem, Kamran Dehghani, Ghader Faraji

Materials Science and Engineering Faculty Research & Creative Works

A combination of severe plastic deformation by equal channel angular pressing (ECAP) and bake hardening (BH) was used to produce high strength ultrafine-grained AA6061 aluminum alloy. 2, 4 and 8 passes of ECAP were performed, and the bake hardenability of samples was tested by 6% pre-straining followed by baking at 200 °C for 20 min. The microstructures obtained for various passes of ECAP were characterized by XRD, EBSD, and TEM techniques. The microstructures were refined from an average grain size of 20 µm to 212 nm after 8 passes of ECAP. Maximum bake hardenability of 110 MPa, and final yield …

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Method And System For Purifying Charged Radioisotopes, Cathy Sue Cutler, Gary John Ehrhardt, Hendrik Petrus Engelbrecht, D. E. Day Jan 2015

Method And System For Purifying Charged Radioisotopes, Cathy Sue Cutler, Gary John Ehrhardt, Hendrik Petrus Engelbrecht, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

The present invention provides a simple and inexpensive method for removing metal and other impurities in a radioisotope solution. The invention further includes the development of a new parent/daughter generator system for collecting the daughter isotope in a concentrated solution.

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Quantitative Modeling Of The Equilibration Of Two-Phase Solid-Liquid Fe By Atomistic Simulations On Diffusive Time Scales, Ebrahim Asadi, Mohsen Asle Zaeem, Sasan Nouranian, Michael I. Baskes Jan 2015

Quantitative Modeling Of The Equilibration Of Two-Phase Solid-Liquid Fe By Atomistic Simulations On Diffusive Time Scales, Ebrahim Asadi, Mohsen Asle Zaeem, Sasan Nouranian, Michael I. Baskes

Materials Science and Engineering Faculty Research & Creative Works

In this paper, molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM) and a phase-field crystal (PFC) model are utilized to quantitatively investigate the solid-liquid properties of Fe. A set of second nearest-neighbor MEAM parameters for higherature applications are developed for Fe, and the solid-liquid coexisting approach is utilized in MD simulations to accurately calculate the melting point, expansion in melting, latent heat, and solid-liquid interface free energy, and surface anisotropy. The required input properties to determine the PFC model parameters, such as liquid structure factor and fluctuations of atoms in the solid, are also calculated from MD …

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Dynamic Phases, Pinning, And Pattern Formation For Driven Dislocation Assemblies, Caizhi Zhou, Charles Reichhardt, Cynthia Olson Reichhardt, Irene J. Beyerlein Jan 2015

Dynamic Phases, Pinning, And Pattern Formation For Driven Dislocation Assemblies, Caizhi Zhou, Charles Reichhardt, Cynthia Olson Reichhardt, Irene J. Beyerlein

Materials Science and Engineering Faculty Research & Creative Works

We examine driven dislocation assemblies and show that they can exhibit a set of dynamical phases remarkably similar to those of driven systems with quenched disorder such as vortices in superconductors, magnetic domain walls, and charge density wave materials. These phases include pinned-jammed, fluctuating, and dynamically ordered states, and each produces distinct dislocation patterns as well as specific features in the noise fluctuations and transport properties. Our work suggests that many of the results established for systems with quenched disorder undergoing plastic depinning transitions can be applied to dislocation systems, providing a new approach for understanding pattern formation and dynamics …

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Composition- And Pressure-Induced Ferroelectric To Antiferroelectric Phase Transitions In Sm-Doped Bifeo₃ System, Fei Xue, Linyun Liang, Yijia Gu, Ichiro Takeuchi, Sergei V. Kalinin, Long-Qing Chen Jan 2015

Composition- And Pressure-Induced Ferroelectric To Antiferroelectric Phase Transitions In Sm-Doped Bifeo₃ System, Fei Xue, Linyun Liang, Yijia Gu, Ichiro Takeuchi, Sergei V. Kalinin, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

A three-dimensional phenomenological model is proposed to describe both ferroelectricity and antiferroelectricity based on the Ginzburg-Landau-Devonshire theory. Its application to the multiferroic Sm-doped BiFeO3 system describes the temperature-, pressure-, and composition-induced ferroelectric to antiferroelectric phase transitions. The constructed temperature-composition and temperature-pressure phase diagrams show that compressive hydrostatic pressure and Sm doping have similar effects on the ferroelectric and antiferroelectric phase transitions. It is also indicated from the temperature-pressure phase diagram that the experimentally observed phase of BiFeO3 under the hydrostatic pressure from 3 GPa to 10 GPa is a PbZrO3-like antiferroelectric phase.

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Nanoscale Mechanical Switching Of Ferroelectric Polarization Via Flexoelectricity, Yijia Gu, Zijian Hong, Jason Britson, Long-Qing Chen Jan 2015

Nanoscale Mechanical Switching Of Ferroelectric Polarization Via Flexoelectricity, Yijia Gu, Zijian Hong, Jason Britson, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide …

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Congenital Epidermoid Cyst Results In Muscle Fusion Defect In The Upper Lip, Fatih Dogan, Ibrahim Hakan Bucak Dec 2014

Congenital Epidermoid Cyst Results In Muscle Fusion Defect In The Upper Lip, Fatih Dogan, Ibrahim Hakan Bucak

Materials Science and Engineering Faculty Research & Creative Works

Epidermoid cysts are rarely detected malformations in the oral cavity. Their development sites are the sublingual, submaxillary, and submandibular spaces. In this paper, we report a three-month-old infant who was admitted to our hospital due upper lip swelling. Magnetic resonance imaging showed that she had a two-centimeter cystic lesion and fusion defects of orbicularis oris muscle. The cyst was surgically removed, and histopathological diagnosis was “epidermoid cyst.” In recent literature, we could not find reports related to orbicularis oris muscle fusion defects because of epidermoid cyst.

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Orientations Of Low-Energy Domain Walls In Perovskites With Oxygen Octahedral Tilts, Fei Xue, Yijia Gu, Linyun Liang, Yi Wang, Long-Qing Chen Dec 2014

Orientations Of Low-Energy Domain Walls In Perovskites With Oxygen Octahedral Tilts, Fei Xue, Yijia Gu, Linyun Liang, Yi Wang, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Many applications of ferroic materials, such as data storage and spintronics, are achieved through the control and manipulation of their domain wall (DW) orientations and configurations. Here we propose a rotational compatibility condition to identify low-energy DWs in perovskites with oxygen octahedral tilt instability. It is derived from the strong DW energy anisotropy arising from the rigidity and corner-sharing feature of the octahedral network. We analyze quantitatively the DWs in SrTiO3 and explain successfully the unusual ferroelectric DW width and energy in BiFeO3.

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Interaction Of Bn-Zro2-Sic Ceramics With Inclusions In Si-Killed Steel, Abhishek Kumar, Vivek Thapliyal, Jeffrey D. Smith Nov 2014

Interaction Of Bn-Zro2-Sic Ceramics With Inclusions In Si-Killed Steel, Abhishek Kumar, Vivek Thapliyal, Jeffrey D. Smith

Materials Science and Engineering Faculty Research & Creative Works

Boron nitride (BN)-based ceramics are often used as containment refractory in thin-strip steel production. The interaction of this material (BN-ZrO2-SiC: -MYCROSINT® SO43) was studied using a steel-inclusion system in a laboratory setup. Isothermal interaction tests were performed to evaluate the interaction of inclusions with this refractory. It was determined that corrosion of the BN refractory occurs through a dissolution mechanism and it was more severe in contact with steel compared to slag. A thermodynamic model was developed using FactSage to study the change in liquid steel/slag composition with refractory interaction. Thermodynamic predictions were in agreement with the experimental …

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First-Principles Study Of 180⁰ Domain Walls In Batio₃: Mixed Bloch-Néel-Ising Character, Menglei Li, Yijia Gu, Yi Wang, Long-Qing Chen, Wenhui Duan Aug 2014

First-Principles Study Of 180⁰ Domain Walls In Batio₃: Mixed Bloch-Néel-Ising Character, Menglei Li, Yijia Gu, Yi Wang, Long-Qing Chen, Wenhui Duan

Materials Science and Engineering Faculty Research & Creative Works

The 180⁰ ferroelectric domain walls (FDWs) have long been regarded as purely Ising type in ferroelectrics, but recent theoretical works suggested that they can also have Néel- and/or Bloch-like rotations. Using a combination of first-principles calculations with phase-field simulations, we studied the 180⁰ FDWs on different crystallographic planes in prototypical ferroelectric perovskite BaTiO3. The polarization profiles of 180 FDWs on (100) and (410) planes revealed that the (100)- and (410)-FDWs both exhibit Néel-like character besides their intrinsic Ising character, while the (410)-FDW also simultaneously shows a Bloch-like oblique of ~6 nm, as a consequence of the deviation of …

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Monoclinic Phases Arising Across Thermal Inter-Ferroelectric Phase Transitions, Yijia Gu, Fei Xue, Shiming Lei, Tom T. A. Lummen, Jianjun Wang, For Full List Of Authors, See Publisher's Website. Jul 2014

Monoclinic Phases Arising Across Thermal Inter-Ferroelectric Phase Transitions, Yijia Gu, Fei Xue, Shiming Lei, Tom T. A. Lummen, Jianjun Wang, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

Thermotropic phase boundaries (TPBs), as thermal analogs of morphotropic phase boundaries (MPBs), are associated with the thermal inter-ferroelectric phase transitions. Similar to an MPB, a TPB exhibits a characteristically flattened energy profile which favors polarization rotation, thus giving rise to a structurally bridging low-symmetry phase. We report on the kinetic process of thermal inter-ferroelectric phase transitions in BaTiO3 and KNbO3 using the phase-field method. The domain structures are found to play key roles in stabilizing the monoclinic phase. In simple domain structures, the monoclinic phase is a transient phase and cannot be stabilized into its neighboring phase regimes. …

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An Investigation Of The Effect Of Direct Metal Deposition Parameters On The Characteristics Of The Deposited Layers, Tarak A. Amine, Joseph William Newkirk, Frank W. Liou Jul 2014

An Investigation Of The Effect Of Direct Metal Deposition Parameters On The Characteristics Of The Deposited Layers, Tarak A. Amine, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

Multilayer direct laser deposition (DLD) is a fabrication process through which parts are fabricated by creating a molten pool into which metal powder is injected as particles. During fabrication, complex thermal activity occurs in different regions of the build; for example, newly deposited layers will reheat previously deposited layers. The objective of this study was to provide insight into the thermal activity that occurs during the DLD process. This work focused on the effect of the laser parameters of newly deposited layers on the microstructure and mechanical properties of the previously deposited layers in order to characterize these effects to …

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Modulating Notochordal Differentiation Of Human Induced Pluripotent Stem Cells Using Natural Nucleus Pulposus Tissue Matrix, Yongxing Liu, M. N. Rahaman, B. Sonny Bal Jul 2014

Modulating Notochordal Differentiation Of Human Induced Pluripotent Stem Cells Using Natural Nucleus Pulposus Tissue Matrix, Yongxing Liu, M. N. Rahaman, B. Sonny Bal

Materials Science and Engineering Faculty Research & Creative Works

Human induced pluripotent stem cells (hiPSCs) can differentiate into notochordal cell (NC)-like cells when cultured in the presence of natural porcine nucleus pulposus (NP) tissue matrix. The method promises massive production of high-quality, functional cells to treat degenerative intervertebral discs (IVDs). Based on our previous work, we further examined the effect of cell-NP matrix contact and culture medium on the differentiation, and further assessed the functional differentiation ability of the generated NC-like. The study showed that direct contact between hiPSCs and NP matrix can promote the differentiation yield, whilst both the contact and non-contact cultures can generate functional NC-like cells. …

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Ceramic Welds, And A Method For Producing The Same, Greg Hilmas, William Fahrenholtz, Jeremy Lee Watts, Harlan James Brown-Shaklee May 2014

Ceramic Welds, And A Method For Producing The Same, Greg Hilmas, William Fahrenholtz, Jeremy Lee Watts, Harlan James Brown-Shaklee

Materials Science and Engineering Faculty Research & Creative Works

A method of producing a ceramic weld, including identifying a ceramic first surface and a ceramic second surface to be bonded together, maintaining a non-oxidizing atmosphere over the first and second surfaces, and engaging the first and second surfaces to define a joint. An arc is generated between an electrode and the joint to create a liquid phase, and the liquid phase is cooled to yield a solid fusion layer, wherein the first and second surfaces are joined in the fusion layer.

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Flexoelectricity And Ferroelectric Domain Wall Structures: Phase-Field Modeling And Dft Calculations, Yijia Gu, Menglei Li, Anna N. Morozovska, Yi Wang, Eugene A. Eliseev, For Full List Of Authors, See Publisher's Website. May 2014

Flexoelectricity And Ferroelectric Domain Wall Structures: Phase-Field Modeling And Dft Calculations, Yijia Gu, Menglei Li, Anna N. Morozovska, Yi Wang, Eugene A. Eliseev, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

We show that flexoelectric effect is responsible for the non-Ising character of a 180° ferroelectric domain wall. The wall, long considered being of Ising type, contains both Bloch- and Néel-type polarization components. Using the example of classic ferroelectric BaTiO3, and by incorporating the flexoelectric effect into a phase-field model, it is demonstrated that the flexoelectric effect arising from stress inhomogeneity around the domain wall leads to the additional Bloch and Néel polarization components. The magnitudes of these additional components are two or three magnitudes smaller than the Ising component, and they are determined by the competing depolarization and flexoelectric fields. …

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The Properties And Structure Of Zinc Magnesium Phosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow Apr 2014

The Properties And Structure Of Zinc Magnesium Phosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Zn-Mg-phosphate (ZMP) glasses, including those with the nominal molar compositions (50 - x)ZnO xMgO 50P2O5 (0 ≥ x ≥ 50) and (60 - y)ZnO yMgO 40P2O5(0 ≥ y ≥ 60), were prepared and properties such as density, refractive index, coefficient of thermal expansion and glass transition temperature (Tg), were measured. The glass transition temperature increases by 100-150 C and the room temperature dissolution rates in water decrease by 1-2 orders of magnitude when MgO replaces ZnO while maintaining a constant P2O5 content. Glass structures were characterized by Raman spectroscopy and …

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Corrosion-Resistant Glasses For Steel Enamels, Richard K. Brow, Signo Tadeu Dos Reis, Michael L. Koenigstein, Genda Chen Mar 2014

Corrosion-Resistant Glasses For Steel Enamels, Richard K. Brow, Signo Tadeu Dos Reis, Michael L. Koenigstein, Genda Chen

Materials Science and Engineering Faculty Research & Creative Works

A cementitious composite material wherein glass-coated steel rods are positioned in a cementitious matrix. The glass composition for coating the steel reinforcing rods includes between about 33-45 weight percent SiO2, 13.5-19.5 weight percent B2O3, 3.5-4.6 weight percent Al2O3, 4.0-13.5 weight percent K2O, 5.5-15.5 weight percent ZrO2, 8.6-15.9 weight percent Na2O, 4.6-5.1 weight percent CaO, 0.6-0.7 weight percent MnO2, 1.0-1.0 weight percent NiO, and 1.0-1.1 weight percent CoO. The glass composition is typically in compression on the rods at ambient temperatures, has a …

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Structural Study Of Na2o-Feo-Fe2o3-P 2o5 Glasses By High-Pressure Liquid Chromatography, Lina Ma, Richard K. Brow Mar 2014

Structural Study Of Na2o-Feo-Fe2o3-P 2o5 Glasses By High-Pressure Liquid Chromatography, Lina Ma, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Three series of Na2O-FeO-Fe2O3-P2O5 glasses with compositional ranges of 3.25 < O/P < 3.5 and 0 < Fe/P < 0.67 were prepared. Glass structure was studied using high-pressure liquid chromatography (HPLC). The average chain-length of phosphate anions decreases with increasing O/P ratios and glasses with similar O/P ratios and greater Fe/P ratios have wider distributions of phosphate anion lengths due to disproportionation reactions in the glass melts. © 2013 Elsevier B.V.

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The Structure And Properties Of Zinc Aluminophosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow, Lionel Montagne, Bertrand Revel Feb 2014

The Structure And Properties Of Zinc Aluminophosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow, Lionel Montagne, Bertrand Revel

Materials Science and Engineering Faculty Research & Creative Works

The glass forming region of the ZnO-Al2O3-P2O5 (ZAP) system was determined and the structures and properties of the glasses were characterized. For glasses with a constant O/P ratio, i.e., with similar average phosphate anion distributions, and with increasing alumina content, there is an increase in molar volume and glass transition temperature and a decrease in density and refractive index. The structures of the ZAP glasses were characterized by Raman spectroscopy, 31P and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and high pressure liquid chromatography (HPLC). Systematically shorter phosphate …

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Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burns Feb 2014

Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burns

Materials Science and Engineering Faculty Research & Creative Works

A multilayer ceramic capacitor, having a plurality of electrode layers and a plurality of substantially titanium dioxide dielectric layers, wherein each respective titanium dioxide dielectric layer is substantially free of porosity, wherein each respective substantially titanium dioxide dielectric layer is positioned between two respective electrode layers, wherein each respective substantially titanium dioxide dielectric layer has an average grain size of between about 200 and about 400 nanometers, wherein each respective substantially titanium dioxide dielectric layer has maximum particle size of less than about 500 nanometers. Typically, each respective substantially titanium dioxide dielectric layer further includes at least one dopant selected …

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Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burn Feb 2014

Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burn

Materials Science and Engineering Faculty Research & Creative Works

A multilayer ceramic capacitor, having a plurality of electrode layers and a plurality of substantially titanium dioxide dielectric layers, wherein each respective titanium dioxide dielectric layer is substantially free of porosity, wherein each respective substantially titanium dioxide dielectric layer is positioned between two respective electrode layers, wherein each respective substantially titanium dioxide dielectric layer has an average grain size of between about 200 and about 400 nanometers, wherein each respective substantially titanium dioxide dielectric layer has maximum particle size of less than about 500 nanometers. Typically, each respective substantially titanium dioxide dielectric layer further includes at least one dopant selected …

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A Novel Injectable Borate Bioactive Glass Cement As An Antibiotic Delivery Vehicle For Treating Osteomyelitis, Hao Ding, Cunju Zhao, Xu Cui, Yifei Gu, Weitao Jia, M. N. Rahaman, Yang Wang, Wenhai Huang, Changqing Zhang Jan 2014

A Novel Injectable Borate Bioactive Glass Cement As An Antibiotic Delivery Vehicle For Treating Osteomyelitis, Hao Ding, Cunju Zhao, Xu Cui, Yifei Gu, Weitao Jia, M. N. Rahaman, Yang Wang, Wenhai Huang, Changqing Zhang

Materials Science and Engineering Faculty Research & Creative Works

Background: A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. Materials and Methods: The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. Results: …

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Development And Application Of Improved Shotctrete Refractory For Aluminum Rotary Furnace Applications, James G. Hemrick, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith, Kelley O'Hara Jan 2014

Development And Application Of Improved Shotctrete Refractory For Aluminum Rotary Furnace Applications, James G. Hemrick, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith, Kelley O'Hara

Materials Science and Engineering Faculty Research & Creative Works

Oak Ridge National Laboratory, in collaboration with refractory manufacturer Minteq International, Inc., academic partner Missouri University of Science and Technology and refractory end users have developed novel refractory systems and techniques to reduce energy consumption of refractory lined vessels. The objective of this U.S. DOE funded project was to address the need for innovative refractory compositions by developing novel gunnable refractory compositions for use in high temperature and high alkali environments. Developed materials utilized new aggregate materials, bond systems, protective coatings, and phase formation techniques. Under this project, materials were developed specifically for aluminum rotary dross furnace applications and a …

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Spinel-Based Refractories For Improved Performance In Coal Gasification Environments, James G. Hemrick, Beth Armstrong, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith Jan 2014

Spinel-Based Refractories For Improved Performance In Coal Gasification Environments, James G. Hemrick, Beth Armstrong, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith

Materials Science and Engineering Faculty Research & Creative Works

Oak Ridge National Laboratory, in collaboration with Minteq International, Inc., Missouri University of Science and Technology and refractory end users, has developed novel refractory systems and techniques to reduce energy consumption of refractory lined vessels. The objective of this U.S. DOE funded project was to address the need for innovative refractory compositions by developing MgO-Al2O3 spinel gunnable refractory compositions utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques. Materials have been developed specifically for coal gasification environments and work has been performed to develop and apply low cost coatings using a colloidal approach for …

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Electric-Field Induced Ferromagnetic Phase In Paraelectric Antiferromagnets, Maya D. Glinchuk, Eugene A. Eliseev, Yijia Gu, Long-Qing Chen, Venkatraman Gopalan, Anna N. Morozovska Jan 2014

Electric-Field Induced Ferromagnetic Phase In Paraelectric Antiferromagnets, Maya D. Glinchuk, Eugene A. Eliseev, Yijia Gu, Long-Qing Chen, Venkatraman Gopalan, Anna N. Morozovska

Materials Science and Engineering Faculty Research & Creative Works

The phase diagram of a quantum paraelectric antiferromagnet EuTiO33 under an external electric field is calculated using Landau-Ginzburg-Devonshire theory. The application of an electric field E in the absence of strain leads to the appearance of a ferromagnetic (FM) phase due to the magnetoelectric (ME) coupling. At an electric field greater than a critical field, Ecr, the antiferromagnetic (AFM) phase disappears for all considered temperatures, and FM becomes the only stable magnetic phase. The calculated value of the critical field is close to the values reported recently by Ryan et al. [Nat. Commun. 4, 1334 (2013)10.1038/ncomms2329] …

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Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang Jan 2014

Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang

Materials Science and Engineering Faculty Research & Creative Works

High-performance piezoelectrics are lead-based solid solutions that exhibit a so-called morphotropic phase boundary, which separates two competing phases as a function of chemical composition; as a consequence, an intermediate low-symmetry phase with a strong piezoelectric effect arises. In search for environmentally sustainable lead-free alternatives that exhibit analogous characteristics, we use a network of competing domains to create similar conditions across thermal inter-ferroelectric transitions in simple, lead-free ferroelectrics such as BaTiO3 and KNbO3. Here we report the experimental observation of thermotropic phase boundaries in these classic ferroelectrics, through direct imaging of low-symmetry intermediate phases that exhibit large enhancements …

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Crystallographic Orientation Of The Ε → Α' Martensitic (Athermal) Transformation In A Femnalsi Steel, S. T. Pisarik, D. C. Van Aken Jan 2014

Crystallographic Orientation Of The Ε → Α' Martensitic (Athermal) Transformation In A Femnalsi Steel, S. T. Pisarik, D. C. Van Aken

Materials Science and Engineering Faculty Research & Creative Works

The presence of a thermal ε- and α-martensite (α') in the as-cast structure of a Fe-0.08C-1.95Si-15.1Mn-1.4Al-0.017N alloy has been revealed by electron backscattered diffraction analysis. The alloy exhibited two a thermal martensitic transformation described by γ → α' and γ → ε → α'. The Shoji-Nishiyama orientation relationship was observed between γ-austenite and ε-martensite, while α-martensite nucleated from γ-austenite exhibited a Kurdjumov-Sachs orientation relationship. Six crystallographic variants of α-martensite consisting of three twin-related variant pairs were observed in ε-bands. A planar parallelism of {0001}ε || {110}α' and a directional relation …

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Environmental Fatigue Of Silicate Glasses In Humid Conditions, Zhongzhi Tang, Richard K. Brow Jan 2014

Environmental Fatigue Of Silicate Glasses In Humid Conditions, Zhongzhi Tang, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Failure strains of commercial silica, soda-lime-silicate, and E-glass fibers were measured using two-point bending in room temperature humid air. Humidity dependence and dynamic fatigue behavior were studied, and the fatigue reaction orders in terms of humidity were determined. In the humidity range tested (~0.1% to ~100%), the dynamic fatigue parameters for silica and E-glass are found to be greater in lower humidity (~0.1% to ~10%), whereas the fatigue parameter for soda-lime-silicate is independent of humidity. The humidity dependence of failure strains for all three glasses was more pronounced in high humidity (~10% to ~100%) than in low humidity (~0.1% to …

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An Evaluation Of Creep Behaviour In Friction Stir Welded Ma754 Alloy, Jiye Wang, Wei Yuan, Rajiv S. Mishra, Indrajit Charit Jan 2014

An Evaluation Of Creep Behaviour In Friction Stir Welded Ma754 Alloy, Jiye Wang, Wei Yuan, Rajiv S. Mishra, Indrajit Charit

Materials Science and Engineering Faculty Research & Creative Works

Effect of friction stir welding (FSW) on microstructure and creep properties of oxide dispersion strengthened (ODS) alloy MA754 were investigated. Fine-grained microstructure developed in the weld zone. TEM results showed some degree of particle agglomeration as a result of intense material flow. Creep tests of the FSW material were carried out at 973 and 1073 K. Power law creep behavior was observed with stress exponent values of 6.9 and 6.3 at 973 and 1073 K, respectively. The results were compared to those of the as-received material. Creep resistance of FSW material was lower than that of as-received material associated with …

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