Power and energy are essential to modern life.  Without sustainable power civilization as we know it cannot continue to exist.  The importance of energy to virtually all sectors of the economy is difficult to overestimate.  It is widely appreciated that current energy technologies are not sustainable, and not surprisingly a plethora of research is directed toward realizing various schemes to solve our energy problems.  This talk will address some factors measuring the growing severity of the energy problems, outline what some viable solutions might look like, highlight some relevant research, and discuss promising near-term prospects.  The talk is directed toward a general audience and discusses a variety of technologies.  While civilization as we know it, in terms of our energy sources, is changing, the future may not be as pessimistic as some of the more dire predictions would suggest.  Indeed, it is entirely plausible that the future will be far preferable to the present in terms of costs, pollution, and standards of living.  Some statistics indicate this future is coming much faster than widely appreciated, and opportunities for innovation and entrepreneur

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Professor Materials Science and Engineering
The Pennsylvania State University

Light-activated molecular conductivity in the photoreactions of vitamin D3
[Williams and Rangel]
Light-activated molecular conductivity in the photoreactions of vitamin D3  Understanding and manipulating molecular conductivity is one  of the initial steps in the development of electrical  circuits and sensors on the nano-scale. Many biological  molecules have been studied as prospective components for  such systems on the basis of their conductive properties. In  this work, we present computational results, obtained by  using ab initio methods, which assert that the UV-activated  reactions of vitamin D3—which are initiated by irradiation of  the molecule 7-dehydrocholesterol (provitamin D3)—act as a  pathway for electrical conductance. Furthermore, we report  experimental evidence of this electrical character and show  that, while, as expected, it depends heavily upon the number  of molecules, there is no observed effect which correlates  directly to the duration of irradiation. This finding  reveals that the conductivity of provitamin D3 can be  activated instantaneously by a relatively short exposure to  UV light. Such a property is desirable in light-activated  nano-circuits, making provitamin D3 a potential molecule for  use in such systems.

Thermomechanical Characterization of Shape Memory Polymers
[Volk]
This study presents the testing techniques used to thermomechanically characterize the material behavior of a shape memory polymer as well as the resulting data. An innovative visual-photographic apparatus, known as a Vision Image Correlation system was used to measure the strain. A series of tensile tests were performed on specimens in which strain levels of 10, 25, 50, and 100% were applied to the material while above its glass transition temperature. After deforming the material to a specified applied strain, the material was constrained and cooled to below the glass transition temperature. Finally, the specimen was heated again to above the transition temperature, and the resulting shape recovery profile was measured. The dependence of the recoverable strain on the heating and cooling rate was investigated in this work. Results showed that strain recovery occurred in a nonlinear fashion with respect to temperature. Results also indicated that the ratio of recoverable strain to the applied strain was a constant value, and was independent of the level of applied strain.”  

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The materials available for transparent applications are limited to a handful of polymers and ceramics, thus only a narrow range of mechanical properties are available. This limitation restricts the design of lightweight transparent laminates since their proper design often relies on the engineer’s ability to specify the acoustic impedance of each layer. Polymer composites offer a wide range of properties, but due to the many interfaces inherent in these materials, they are not typically transparent. In this talk several routes towards the manufacture of transparent composite materials will be discussed. Nanocomposites are manufactured by infiltrating nanoporous glass as well as electrospun nanofiber mats with polymer precursors. Such systems are transparent because the reinforcement length scale is much smaller than the critical size for visible scattering, greatly reducing the requirements on refractive index (RI) matching. In order for conventional, (large fiber diameter) composites to maintain transparency, constituent RI’s must match index to better than 0.001. As a result these systems must accommodate small, thermally-induced RI changes in the polymer matrix that can render an otherwise transparent composite translucent or opaque. Incorporating electro-optical chromophores into the matrix permits active RI control while coating conventional glass fibers with a thick layer of nanoparticles reduces the requirement for index matching and makes the material less sensitive to changes in temperature.
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In this talk a novel methodology for high temperature synchrotron X-ray diffraction (XRD) using a quadrupole lamp furnace (QLF) and a Curve Image Plate Detector (CIPD) will be presented. The combined setup of QLF and CIPD detector, together with today’s intense X-ray synchrotron sources, offers considerable promise in revolutionizing the way in which high temperature XRD studies will be performed. The ability to rapidly acquire high resolution XRD data simultaneously over a wide 2? range, for temperatures extending from room temperature to 2000 °C in air, along with the capability of rapid heating (~ 200 °C/sec) and quenching is very unique. Coupled with the Rietveld profile fitting method, various in-situ high temperature investigations that are now possible include (a) structural phase transformations (b) crystallographic thermal expansion behavior, (c) microstructural evolution with temperature, (d) chemical reaction kinetics e.g. of binary and ternary mixtures of ceramic materials, (e) oxidation studies of non-oxide ceramics such as borides, and (e) phase equilibria and phase diagrams based upon them.
    A long term vision for applications of phase transformations will be presented in which unit cell volume changes or unit cell shape changes are considered. While positive volume changes occurring on cooling can lead to “transformation toughening” (e.g as in zirconia, or the lanthanide sesquioxides), negative volume changes would lead to “transformation weakening” (e.g., enstatite, cristobalite). The latter effect could be useful for interphase debonding in ceramic matrix composites, such as laminates, fibrous monoliths or fiber reinforced CMCs, leading to overall toughening,. When one considers systems in which the unit cell shape change is more dominant at transformation, (e.g. second order transformation in the rare earth niobates), one is led to ferroelastic transformations involving a group-subgroup relationship, in conjunction with ferroelasticity involving domain rearrangements. Such phenomena could lead to shape memory behavior, “rubber-like” behavior or “smart” systems in ceramics.
    Geopolymers (Al2O3•M2O•4SiO2•11H2O) where M = Na, K, Cs) are rigid, alumino-silicate, pre-zeolitic, hydrated gels containing group I, charge-balancing cations and made under ambient temperatures. The gel is an amorphous, cross-linked, impervious, acid-resistant structure, which is 40 % nanoporous (3 nm pore radius) and nanoparticulate (5-10 nm). This new class of ceramics exhibit novel microstructures and interesting mechanical and chemical properties. In this study, the formation of pollucite (CsAlSi2O6) and leucite (KAlSi2O6) from geopolymer precursors was observed. Both phases were found to crystallize at around 900-950oC, and the resultant ceramic phase consisted of a crystalline phase surrounded by an amorphous matrix. Leucite composition geopolymers crystallized up to 80 wt% KAlSi2O6, which is much higher than one can obtain via traditional dental porcelain routes.

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The secrets of the superconducting mechanism in the cuprates are still widely thought to be worth a Nobel prize. But the applications depend critically on understanding a quite different issue, grain boundaries, since misoriented grains are still the principal block to current in polycrystalline forms. Polycrystalline forms of conductor are critical to the technology developments that are now emerging and that were so easily – and so wrongly – predicted to be within reach 20 years ago. The classic experiment is that of Dimos, Mannhart and Chaudhari in 1987 that showed a rapid fall off in critical current density across grain boundaries for misorientation q of more than about 5°. Detailed study of many types of simple [001] tilt bicrystal showed that this fall off was exponential, the critical angle only being 3°. Thus a “single-crystal-by-the-mile” technology is needed in order to avoid loss of current at blocking grain boundaries. Development of this technology, now achieved, is the principal reason that applications have taken so long. But in fact some relaxations from such stringent requirements are possible. My group is particularly interested in the relaxations – in doping carriers into the GB so as to raise the local superconducting order parameter, in producing meandered GBs that perturb vortices much less than planar, “scientific” GBs, and perhaps most interesting for the long term the current paths that still remain in completely untextured cuprate conductor forms. I will describe recent work in these areas where unexpected discoveries about this very important issue of current flow in polycrystalline cuprates are still occurring.

Multi-functional materials can respond to more than one external stimulus. One important family of such materials would be those with magnetization-polarization interactions: however, prior searches for such systems with strong exchange have proven elusive. In this talk, we will discuss recent advances in magnetoelectric materials that use a different approach: ‘Zhong young zhi dao’ the ancient Chinese ‘doctrine of the mean or middle grounds’, where inherent compromise to conflict is essential. Investigations of multi-ferroic behavior will be present in magnetoelectric (i) single crystals and epitaxial films of BiFeO3; and (ii) laminate composites of piezoelectric and magnetostrictive layers. We will demonstrate that strong interaction can be achieved between the spin and polarization subsystems. The results offer an approach to a complete electromagnetic packaging material: which could have important ramifications in sensors, voltage reading of spin states, power electronics, and antennas.

Modeling the electrical effects of radiation damage in semiconductor devices requires a detailed description of the properties of point defects generated during and subsequent to irradiation. Such modeling requires physical parameters, such as defect electronic levels, to describe carrier recombination. Density functional theory (DFT) is the method of choice for first-principles simulations of defects. However, DFT typically hugely underestimates the fundamental band gap in semiconductors, and the band gap is the energy scale of interest for defect levels. Moreover, boundary conditions in the supercell approximation used in DFT calculations of defects also can inject large errors and uncertainties. I describe a new, more rigorous methodology for supercell calculations that incorporates a proper treatment of electrostatic boundary conditions, locates a fixed chemical potential for the net defect electron charge, includes the bulk dielectric response, and creates a robust computational model of isolated defects. Using this methodology, the computed DFT defect level spectrum for a wide variety of Si defects spans the experimental Si gap, i.e., exhibits no band gap problem, and the DFT results agree remarkably well with experiment for those values that are experimentally known. The new scheme adds rigor to computing defect properties, and has important implications for density functional theory development.