Tag: Fall 2010

Crystallographic Domain Engineering of Ferroelectric Single Crystals

Friday, November 19, 2010 3:00 pm – 4:00 pm (1 of 2 speakers)
Room 610, M&M Building

Jie Zhou
Graduate Student
Materials Science and Engineering
Michigan Technological University

Abstract

Phase field modeling and computer simulation is performed to study the mechanisms ofcrystallographic domain engineering technique for ferroelectrics. It is found that both domainconfigurations and domain sizes in ferroelectric single crystals can be controlled throughsophisticated thermal and electrical conditions imposed on the materials during ferroelectricphase transformations. The simulations reveal that minimal domain sizes and highest domainwall densities are obtained with intermediate magnitude of electric field applied along non-polaraxis of ferroelectric crystals, while lower and higher fields produce coarser domains and lowerdomain wall densities. It is found that temperature also plays an important role in domain sizecontrol. The simulations show that selection of polar domain variants by external electric fieldduring nucleation stage of ferroelectric phase transition significantly affects subsequent domaingrowth and evolution kinetics and controls the formation and sizes of twin-related lamellardomains. It is also found that the long-range electrostatic and elastostatic interactions generateinsurmountable energy barrier to isolated ferroelectric nucleation, and independent nucleation offerroelectric phase in the context of classical nucleation theory is impossible. In order tocircumvent such an energy barrier, ferroelectric nucleation exhibits strong spatial correlation andself-organization behaviors, and ferroelectric phase transformation proceeds via spatial andtemporal evolution of self-accommodating domains that provide a low-energy kinetic pathwaythroughout the entire phase transformation process.


Particles at Fluid Interfaces and Effects on Coarsening Kinetics

Friday, November 19, 2010 3:00 pm – 4:00 pm (1 of 2 speakers)
Room 610, M&M Building

Tianle Cheng
Graduate Student
Materials Science and Engineering
Michigan Technological University

Abstract

A newly developed diffuse interface field approach (DIFA) is employed to perform simulationstudy of particles assembly at fluid interfaces. The model employs diffuse interface fields todescribe arbitrary particle shapes as well as multi-phase fluid. It takes into account capillaryforces associated with fluid interfaces, inter-particle short-range repulsions due to mechanicalcontact and/or steric force, hydrostatic force, and Brownian motion force. The model is appliedto simulate particle self-assembly in fluid that undergoes spinodal decomposition. It is shownthat particles stabilize the two-phase fluid morphology by slowing down the coarsening kinetics,and the fluid interfaces are finally arrested by particles closely packed at the interfaces. Inparticular, the effects of particles on the curvature of the fluid interfaces are discussed. It isfound that capillary force and pressure both play important roles in equilibrium of particles atfluid interfaces as well as the interface curvature. The latter is essential for coarsening kineticsof spinodal decomposition.


The Theory of Wetting Including the Fundamentals of Designing the Superlyophobic State of Materials

Tuesday, November 9, 2010 10:00 am – 11:00 am
Room 610, M&M Building

Prof. Ludmila Boinovich
Russian Academy of Science
Moscow, Russia

Abstract

The dominant role of the long-range surface forces in wetting phenomena is widely accepted. Theoretical grounds of the design of hydrophobic materials and coatings and the specificfeatures of the superhydrophobic state of the surface will be discussed on the basis ofthermodynamic and using the concept of surface forces which are characterized by the isothermof disjoining pressure. This concept allows one to explain the peculiarities of wetting and toshow that in general, bulk liquid (drop or concave meniscus) coexists with the substrate which isnot dry, but coated by wetting or adsorption film of liquid. The problems of ageing anddegradation of syperhydrophobic coatings will be outlined.

Biography

Scientific career of Ludmila Boinovich began in 1980s in the laboratory of famous Russian scientistB.V. Derjaguin. Her research activities, both theoretical and experimental, have been centered on molecular andsurface physics. She has discovered and studied several new physical mechanisms of surface forces including thephonon mechanism of surface forces, explaining the influence of confining phases on inter- and intramolecularinteractions in the intervening liquid layer. She has introduced the notion on dynamic structure of liquid innanosystems, characterized by the density of vibrational states. The analysis of the dispersion systems withmulticomponent dispersion phase allowed her to made pioneering advances at the theoretical level, for imagecharge mechanism of surface forces, associated with the polarization of confining phases by the electrostatic fieldof solute molecules. Her studies on phase transitions in nano-sized systems lead to establishing the physicochemical parameters determining the shift of melting/freezing temperatures at the interfaces, in wetting films,aerosols and porous matrices. Ludmila Boinovich and her team have developed a series of new spectroscopicmethods and devices for studying the structure of liquids in nanosize systems and have found experimentally thethickness dependent deviation of liquid structure in thin layers.

Among various awards and honors she received the Gold medal of ICEPEC (Institut Communautaire Europeenpour la Promotion des Enterprices Commerciales) for her contribution to the promotion of scientific results inengineering applications. She has earned a reputation as an outstanding lecturer and teacher who has motivatedand inspired the younger generations of Russian surface and colloid physicists. In 2006 Prof. Boinovich waselected to be a Corresponding Member of Russian Academy of Sciences.


The Modern State of the Theory of Surface Forces in Colloid Systems and Thin Liquid Films

Monday, November 8, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

Prof. Ludmila Boinovich
Russian Academy of Science
Moscow, Russia

Abstract

A modern physical theory, which describes the state and stability of liquid films and thedispersed and colloid systems, is based on the analysis of the surface forces acting across thinliquid films separating particles or macroscopic bodies. The major recent advances in the theorywill be considered. Limitations intrinsic in the conventional DLVO theory will be briefly outlined.Studies devoted to the analysis and calculations of non-DLVO interactions of different nature willbe reviewed. Particular attention will be paid to the forces caused by the inhomogeneity of liquidinterlayers. The applicability of the known approaches for solving the nanotechnologychallenges will be discussed.

Biography

Scientific career of Ludmila Boinovich began in 1980s in the laboratory of famous Russian scientistB.V. Derjaguin. Her research activities, both theoretical and experimental, have been centered on molecular andsurface physics. She has discovered and studied several new physical mechanisms of surface forces including thephonon mechanism of surface forces, explaining the influence of confining phases on inter- and intramolecularinteractions in the intervening liquid layer. She has introduced the notion on dynamic structure of liquid innanosystems, characterized by the density of vibrational states. The analysis of the dispersion systems withmulticomponent dispersion phase allowed her to made pioneering advances at the theoretical level, for imagecharge mechanism of surface forces, associated with the polarization of confining phases by the electrostatic fieldof solute molecules. Her studies on phase transitions in nano-sized systems lead to establishing the physicochemical parameters determining the shift of melting/freezing temperatures at the interfaces, in wetting films,aerosols and porous matrices. Ludmila Boinovich and her team have developed a series of new spectroscopicmethods and devices for studying the structure of liquids in nanosize systems and have found experimentally thethickness dependent deviation of liquid structure in thin layers.

Among various awards and honors she received the Gold medal of ICEPEC (Institut Communautaire Europeenpour la Promotion des Enterprices Commerciales) for her contribution to the promotion of scientific results inengineering applications. She has earned a reputation as an outstanding lecturer and teacher who has motivatedand inspired the younger generations of Russian surface and colloid physicists. In 2006 Prof. Boinovich waselected to be a Corresponding Member of Russian Academy of Sciences.


Electromechanical Molecular Actuators Based Quantum Mechanical Mechanisms

Thursday, November 4, 2010 11:00 am – 12:00 pm
Room 610, M&M Building

Prof. Miklos Kertesz
Department of Chemistry
Georgetown University
Washington DC

Abstract

Charged or neutral radicals often display π-stacking geometries that show signs ofintermolecular covalent bonding based on the partial occupancy of π-orbitals. This interaction issensitive to the number of π-electrons available for this bonding and goes beyond van derWaals interactions. We analyze known cases of intermolecular π-bonding in various radicaldimers and chains and connect the intermolecular bonding properties to observed properties.The simulations involve molecular and periodic first principles density functional theorycalculations. Various stacked chains are analyzed for their suitability as electrochemically drivenactuating molecules and compared with other mechanisms of electrochemical actuationincluding those based on polyacetylene and carbon nanotubes as well as those based onlocalized 2 center/3 electron bonds.

Relevant references

“Dimensional Changes as a Function of Charge Injection in Single Walled Carbon Nanotubes”Sun, G.Y.; Kürti, J.; Kertesz, M.; R. H. Baughman,  J. Am. Chem. Soc. 2002, 124, 15076-15080.

“Electronic Structure of Helicenes, C2S Helicenes, and Thiaheterohelicenes”Yong-Hui Tian, Gyoosoon Park, Miklos Kertesz, Chem Mater. 2008, 20, 3266-3277.

“Molecular Actuators Designed with S…N(sp(2)) Hemibonds Attached to a ConformationallyFlexible Pivot“ Tian, Y.-H.; Kertesz, M. Chem. Mater. 2009, 21, 2149-2157.

“Is There a Lower Limit to the CC Bonding Distances in Neutral Radical ?-Dimers? The Case ofPhenalenyl Derivatives”, Tian, Y.-H.; Kertesz, M. J. Am. Chem. Soc. 2010. 132, 10648-10649.


Pt-Re Interactions under Hydrothermal Conditions for Aqueous Phase Reforming of Bio-derived Liquids

Wednesday, October 6, 2010 11:00 am – 12:00 pm
Room 610, M&M Building

David L. King
Pacific Northwest National Laboratory

Abstract

Hydrogen production from the aqueous phase reforming of glycerol over 3%Pt-Re/C  has beenstudied,  and the results compared with a Re-free 3%Pt/C catalyst. Although the Pt/C catalyst isvery selective toward the production of hydrogen, catalytic activity is low. Addition of Resignificantly increases the conversion of glycerol, at some loss of hydrogen selectivity to lighthydrocarbons and water-soluble oxygenates. This loss of H2 selectivity can be traced to anincrease in acid-catalyzed dehydration pathways.  The highest hydrogen productivity among thecatalysts tested is achieved with a 3%Pt-3%Re/C catalyst with added KOH base, whichmediates the acidity. The observed product distributions can be understood in terms of thedifferent reaction pathways that become emphasized depending on catalyst composition andpH.

The structure of Pt-Re nanoparticles supported on carbon following exposure to a hydrogenreducing environment and subsequent hydrothermal conditions has been studied using in-situ xray photoelectron spectroscopy (XPS) and aberration-corrected scanning transmission electronmicroscopy (STEM) with associated energy-dispersive spectroscopy (EDS). Thephysicochemical and electronic structure of PtRe nanoparticles under hydrothermal conditionshave been correlated to the catalyst selectivity in the aqueous phase reforming of glycerol. Weshow that Re addition to Pt results in charge transfer from Pt to Re-Ox under hydrothermalreaction conditions. The catalyst acidity increases with increasing Re:Pt ratio, and the higheracidity is shown to favor C-O over C-C cleavage. This results in higher selectivity to liquidproducts and alkanes at the expense of hydrogen production. We discuss the possible origins ofacidity enhanced by the addition of Re.

Biography

Dr. David L. King is a Laboratory Fellow (the highest rank that PNNL science and engineering staff canattain) and Team Lead of the Catalysis Science and Application Group at Pacific Northwest National Laboratory(PNNL) in Richland, Washington.  He is currently Associate Lead for the Energy Conversion Initiative, a laboratorylevel initiative which has as its goal to develop PNNL as a Center of Excellence for Air- and Water-NeutralHydrocarbon Conversions, with a major focus on clean coal. He has had a long-standing interest in production ofhydrocarbon liquids from coal and biomass. Dr. King holds fifteen patents, with several pending, and over forty peerreviewed publications. Dr. King has a Ph. D. from Harvard University in physical chemistry.


Composite Materials in Large Civil Engineering Structures – Design Optimization

Friday, October 1, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

John Pilling
Technical Director, Electric Park Research

Abstract

The choice of materials for use in load bearing civil engineering structures are often determined by costsimply because of the large volumes of materials involved.  One instance of the large scale use ofpolymeric materials is in the rehabilitation of cracked, corroded or collapsed pipes that were originallyinstalled under most of the large American cities during the late 1800s. In many instances it is extremelycostly or impossible to dig up and replace the existing pipes. Rehabilitation by lining the pipes with apolymeric material is common practice. HDPE is currently favoured for small diameter internallypressurized pipes such as water and gas mains and is usually pulled into and through the existing pipes.However, this is not practical for many of the waste and storm water pipes that are either non-circular orlarger than about 24” in diameter as the pipe wall becomes excessively thick in order to support theimposed loads without buckling or fracture.  Combining micromechanics of materials, elasticity theory oflaminates, and a geotechnical analysis of the loading of buried pipes, it is possible to design compositestructures that can support all the imposed loads and be easily installed in the existing collapsed pipe.The design process involves a geotechnical analysis of the imposed soil, water and rolling loads (vehicle,rail or aircraft) to determine the imposed pressure on the pipe. The pressure that a given pipe wall willsupport depends on the flexural rigidity of the  pipe wall (EI), its strength (s)  and a critical designdimension (D), usually the diameter of the pipe, but can be a critical radius of curvature or the length of astraight section when the pipe is non-circular. The actual equations used to determine the pressure thatcan be supported depend on the shape of the pipe, the type of loading and the country in which the pipeis to be installed (National Design Codes).  An “Ashby” type analysis is then completed in which therequired pipe thickness to support the imposed loads is determined as a function of the internal structureof a laminated composite given that the mechanical properties of the pipe wall are themselves functionsof thickness. The cost of the design is then calculated.  Typical microstructural variables include the typeof reinforcing fibre, the fibre spacing (volume fraction), resin type and fibre position within the laminatedstructure, i.e thickness.  A numerical solution method is employed to determine the combination ofmicrostructural variables that produce the composite with the minimum cost. Each rehabilitation projectproduces a unique composite microstructure which can be easily manufactured, on demand, usingtechnology currently deployed in the textile industry.  Typical municipal rehabilitation projects cangenerate material costs savings in the millions of $ range over conventional monolithic materials.  Thispresentation explains how micromechanics and elasticity theory are combined with typical civilengineering design codes to produce cost minimized structural composites. Examples of pipes andinstallations will be included.


Innovation in Metals Production – Faster, Cheaper, Safer

Wednesday, September 29, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

Prof. David Robertson
Department of Materials Science and Engineering
Missouri University of Science and Technology
Rolla, MO

Abstract

Metals constitute an important class within the more general category of materialsand steel is by far the most produced of all the metals.  The lecture will giveexamples of how basic scientific knowledge is gained and then used to meet thetechnical challenges and opportunities that arise as we strive to satisfy the everrising demand for metals in a world where sustainability is a vital issue.

Biography

David Robertson is Professor Emeritus at the Missouri University ofScience and Technology.  He was the TMS Extractive Metallurgy Lecturer in 2008and Director of the national Center for Pyrometallurgy (funded by the US Bureauof Mines) from 1985-1996.  Dr. Robertson’s teaching and research interests havecovered the smelting and refining of all the metals – from aluminum through copperand steel to zinc.  He and his colleagues have always worked closely withindustry, both in the US and internationally. The citation for the Elliott LecturerAward reads:  “For application of process modeling to steel refining technology,and for advances in quantitative analysis of metallurgical processes.


Introduction to Pearson’s Crystal Data Software TUTORIAL

Friday, September 17, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

Edward A. Laitila
Department of Materials Science and Engineering
Michigan Technological University

Abstract

A new software package, Pearson’s Crystal Data, is available to the campuscommunity. The software has been deployed to select areas of the campus.Pearson’s Crystal Data contains a large amount of information on crystallineinorganic materials and would be beneficial to anyone working with solidcrystalline materials. Information in the database includes atomic positions,symmetry data, crystal models, lattice parameters, x-ray diffraction spectra, andmore. An introduction to the software will be provided along with a tutorial of thebasic searching functions. Advanced searches will be introduced as well as thevarious types of data presentation along with tips on how to export importantinformation.

Individuals are welcome to install the software on their laptops and bring it tofollow along the tutorial.