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Focus On Materials
Materials Day 2006 - Posters
Materials Characterization
- D10 - Ultraviolet Raman Spectroscopy of Nanoscale Ferroelectric Structures
D. A. Tenne, X. X. Xi, A. Soukiassian, V. Vaithyanathan, J. H. Haeni, W. Tian, D. G. Schlom, Y. L. Li, L. Q. Chen, X. Q. Pan, A. Bruchhausen, A. Fainstein, A. Cantarero, R. S. Katiyar
Abstract: Fundamental properties of ferroelectric nanostructures can be dramatically different from those of homogeneous bulk ferroelectrics. Experimental investigation of the lattice dynamics in nanoscale ferroelectrics is a very difficult task, hardly feasible with conventional visible or infrared spectroscopies. Here we present the first experimental study of ferroelectric short-period SrTiO3/BaTiO3 superlattices (SLs) by ultraviolet (UV) Raman spectroscopy. Using UV excitation enabled the observation of phonons in SLs where the ferroelectric layers are 2-3 nm thick. The results show that due to strain in the SLs, BaTiO3 layers remain in the tetragonal phase in the temperature range from 80 to 400K. Features attributed to the first-order Raman scattering in SrTiO3 layers indicate that SrTiO3 in the SLs is polar in the temperature range studied. The result has demonstrated the capability of UV Raman spectroscopy and already shed light to the phase transitions of nanoscaled ferroelectrics.
URL: http://www.personal.psu.edu/faculty/x/x/xxx4/
- E06 - Microwave Loss Dielectric Characterization of Silicon Carbide Wafers
T. E. Bogart, D. W. Snyder, W. J. Everson, R. D. Gamble, E. J. Oslosky, E. Furman, S. Perini, M. Lanagan
Abstract: Semi insulating silicon carbide (SiC) wafers have been developed for use as a substrate for high frequency devices. A nondestructive characterization technique to measure the dielectric properties of SiC wafers at the high frequencies the devices will be operating at is being developed as a method to select SiC wafers that produce the highest yield of working devices. The dielectric loss is measured at approximatly16 GHz in a split microwave cavity using a HP 8510C network analyzer. Initial results show a correlation between the dielectric loss and resistivity, where the resistivity was measured using a Contact less Resistivity Mapping system (COREMA). The uniformity of dielectric loss across SiC wafers has been looked at using a split post dielectric resonator cavity fixed at 5.5GHz to measure the dielectric loss at five points on a wafer. The study also includes a comparison of dielectric loss to temperature and a look at photoconductivity seen in SiC wafers.
URL: http://www.electro-optics.org
- E07 - Enhanced Cooperativity Below the Caging Temperature of Glass-Forming Liquids
B. M. Erwin, R. H. Colby
Abstract: A cooperative mechanism is invoked to explain the acute property changes observed in glass-forming liquids near the glass transition temperature Tg. This theory implies the existence of cooperatively rearranging regions (CRR) as characterized by a dynamic length scale, which is observed in both 4-Dimensional NMR and computer simulation. Armed with the temperature dependence of this length scale and the fractal dimension of the CRR (from simulations) a simple scaling model for glassy behavior can be constructed. Using characteristic caging and critical temperatures for each glass, this scaling model is applied to the temperature dependence of probe dynamics, viscosity, and the alpha-relaxation for a series of organic glass-formers. Near-Tg self-diffusion and probe diffusion data are used to verify the predicted temperature dependence of the cooperative length scale.
- E08 - Atomic Structure and Chemistry of Internal Interfaces
E. Dickey
Abstract: Analytical transmission electron microscopy (TEM) is a powerful tool for studying the internal structure and chemistry of solid-state interfaces at the angstrom to nanometer length scale. This poster will overview the TEM facilities available in the Penn State Materials Research Institute and show ongoing research activities that highlight the importance of this characterization technique for solving materials science problems.
- E09 - Fracture and Deformation of Porous Materials
D. J. Green
Abstract: The poster is a brief summary of recent research projects. These include 1) The use of residual stresses in strengthening glasses and ceramics, 2) The stresses and distortion that arise during the densification of powders during sintering, 3) Contact damage in thin films, 4) The mechanical properties of powder compacts, 5) Fracture and deformation of brittle materials.
URL: http://www.ems.psu.edu/~green/djg.html
- E10 - Microstructural Characterization and Impression Creep Testing of SiAlON Ceramics
K. M. Fox, J. R. Hellmann, E. C. Dickey, D. J. Green, R. Yeckley
Abstract: Silicon aluminum oynitride (SiAlON) materials have been developed for use as high speed cutting tools, gun tubes, and more recently in state-of-the-art microturbines for remote power generation. This study addresses the role of rare earth dopants on microstructural and crystalline phase evolution and the high temperature strength and creep resistance of SiAlON. X-ray diffractometry coupled with Electron Probe Microanalysis (EPMA) and High Resolution Transmission Electron Microscopy(HRTEM) have been employed to quantify the crystalline phase evolution, and to identify the composition, structure and distribution of the glassy intergranular phase. Creep studies to 1450 °C, using a high temperature impression creep system are underway to examine the role of grain morphology and glass phase distribution on high temperature deformation behavior. This work has been funded by Kennametal Inc. and the Department of Energy under contract numbers 65542 and DE-AC05-00OR22725, respectively.
- E11 - Thermomechanical Properties and Performance of Materials at the Nano-, Micro-, and Macroscale
J. R. Hellmann, K. M. Fox, J. A. Howell, W. G. Luscher, B. Rangarajan, A. Shindyapin, M. Burton, K. Hoff
Abstract: Funded by NSF, DoE, DoD, and industry, our research focuses on the effect of processing and microstructural design on thermal, elastic, and mechanical properties of materials at the nano- to macro-scale. Our studies on laminated ceramic composites have resulted in new cutting tools with improved high speed interrupted cutting performance. Complementary studies on the creep behavior of SiAlON ceramics have recently spun off into a new program on developing laminated ceramic armor composites with enhanced ballistic resistance. Our research on the elastic and mechanical properties of materials at the nanoscale have enhanced the reliability of float glass in automotive and structural applications. Our work on ceramics produced from industrial byproducts is enabling the development of high specific strength materials for enhanced recovery of oil and natural gas. Our unique high temperature test capabilities can be applied to other materials, devices, and systems on an as needed basis.
- E12 - Molecular-Level Characterization of Advanced Materials and Their Interfacial Interactions: Structure, Chemistry, and Dynamics Probed With Solid-State Nuclear Magnetic Resonance
K. T. Mueller, R. A. Fry, N. M. Washton, R. A. Golombeck, G. S. Crosson, G. M. Bowers, R. Kumar
Abstract: Our research explores the development and implementation of novel solid-state nuclear magnetic resonance (NMR) methods for the characterization of structure, chemistry, and dynamics. Our main focus is now the study of interfaces of oxide materials, where we are probing reactive species by a variety of methods. We have recently proposed a "reactive surface area" model for scaling of reaction rates, where we utilize probe molecules with strong NMR signals. In these studies we take advantage of the extreme sensitivity of NMR resonance frequencies and relaxation parameters to local bonding environments. Other studies which will be presented have focused on hydroxide-promoted dissolution and reprecipitation at clay surfaces, the acid-promoted transformation of aluminum coordination environments at aluminosilicate glass surfaces, and the use of pulsed-field gradient NMR methods for measurement of the diffusion behavior of oligonucleotides in constrained environments.
URL: http://research.chem.psu.edu/ktmgroup/
- F01 - Fiberglass: Surface Chemistry and Structure
C. Pantano, K. T. Mueller, V. Bakaev, B. Hengstebeck, R. Kumar, R. A. Fry, N. Lonnroth, R. Schaut, B. Smith, N. M. Washton
Abstract: The wide range of compositions, processing methods and applications for commercial fiberglass necessitates their extensive characterization for quality control and new product development. We have established some unique methods of surface analysis, electron and chemical force microscopy, gas chromatography, nuclear magnetic resonance, and nanoindentation to meet this need. The surface reactivity of fiberglass must be sufficient to affect its on-line coating, but stable to the aqueous, sometimes acidic, service environment. We are currently engaged in the study of chemisorbed water on silica and multicomponent silicate fibers; fiberglass wool and its interface with polymer binders; boron- and magnesium-oxide effects in fiberglass reinforcement; surface forces on silanized fiber; surface chemistry and structure of basaltic fibers; and nanomechanical properties of fiberglass.
URL: http://www.mri.psu.edu/faculty/pantano/
- F02 - Glass Surfaces, Interfaces and Coatings
C. Pantano, V. Bakaev, G. D. Barber, B. Hengstebeck, M. Krohn, E. Leed, N. Lonnroth, J. Overburg, J. Ryan, J. Rygel, R. Schaut
Abstract: Our work is focused primarily on understanding the surface properties of glass. It is driven by the multitude of commercial applications for glass, and especially, the added value provided by applying functional coatings to glass. We use computer modeling techniques and a wide variety of instrumental surface analysis techniques to characterize the relationships between composition and surface reactivity. We have established unique methods including chemical force microscopy, streaming potential, inverse gas chromatography, and nanoindentation to probe surface adhesive forces, charge, adsorptivity and mechanical properties. We are especially interested in silane, sol/gel and nanostructured coatings on glass, and their commercial applications, especially in biotechnology. We also work closely with the glass industry to apply these methods and coatings to the surfaces of manufactured glass products such as fiberglass, float glass, display glass and optical components.
URL: http://www.mri.psu.edu/faculty/pantano/
- F03 - Ionomers, Polyelectrolytes, and Dielectric Spectroscopy: Improving Ionic Polymers by Understanding Polymer Dynamics
P. Atorngitjawat, R. Klein, J. Runt
Abstract: Ions attached to polymer chains can dramatically improve both the structural and electrical properties of polymers. Here we present the dielectric properties of two parallel types of ionic polymers: high Tg, water-insoluble ionomers and low Tg, water-soluble polyelectrolytes. Dielectric (impedance) spectroscopy has provided us with comprehensive information about these two polymer types, thus clarifying important structure-property relationships. In the case of ionomers, understanding nano-phase separation and local processes allows us to maximize the barrier properties for packaging materials. In the case of polyelectrolytes, understanding ion dissociation and ion mobility allows us to optimize the conductivity of electrolytes for Li ion batteries. Understanding characteristics such as nano-cluster phase separation and ion dissociation facilitates design of new polymeric materials from the bottom up.
- F04 - Polymer Dynamics and Nanoscale Structure
J. Runt
Abstract: This poster will provide an overview of recent activities in our research group. The dynamics of multicomponent polymer systems are under active investigation, as many applications (e.g. ion conduction in polymer electrolytes, controlled drug release) are realized through polymer molecular motions. The principle experimental tool used in these studies is dielectric (impedance) spectroscopy. A second area is self-assembly of polymers derived from renewable resources. We are particularly interested in model polylactides and polysaccharides. Finally, we are investigating the relationship between nanoscale, phase separated structure and properties of polyurethane block copolymers important in biomedical applications.
- F05 - Ordering of the Beta Phase in Alpha2/Beta-Titanium Alloys in the Ti-Ru-Al System
S. Rajsiri, E. Ryba
Abstract: This work primarily focuses on the possibility of obtaining an ordered beta phase in Ti-Al and Ti-Ru-Al alloys at room temperature, based on the most recent Ti-Ru-Al phase diagram (Grytsiv, et al, 2003). Arc-melted Ti-Al and Ti-Al-Ru alloys were heat treated at 1300 °C, in proposed ordered region of the beta phase field and rapidly quenched in water to maintain the beta phase to room temperature. So far, only mixtures of beta and alpha2 phases have been obtained, as shown by optical microscopy and X-ray diffraction. Ru should stabilize the beta phase in these alloys. Ru may also play a role in the ordering of beta phase.
- F06 - Focused Ion Beam Capabilities at the Materials Characterization Lab
J. Shallenberger, J. Kulik, J. McIntosh, E. J. Basgall
Abstract: Focused ion beam (FIB) is the newest addition to MCL's microscopy services and provides a very unique capability. The dual characterization and fabrication capabilities of the FEI Company Quanta 3D FIB will be summarized. Information about gaining access to the entire MCL facility containing over 20 analytical techniques will be available for both university and industrial partners.
URL: http://www.mri.psu.edu/mcl
- F07 - Synthesis and Structure of a Novel Aluminophosphate Built from 3-Rings
D. E. W. Vaughan, H. P. Yennawar, A. J. Perrotta
Abstract: Reacting a pre-made aluminophosphate (ALPO, P/Al=0.9) gel with an aqueous-tripropylamine solution of KOH and TMAOH we have synthesised a new porous 3D crystalline structure (PSU-2). Single crystal structure analysis shows that it is built from pairs of 3-rings of P-tetrahedra and Al-octahedra; orthorhombic (Pnna) with a=12.741Å, b=10.221Å, c=6.224Å. Associated phases include ALPO analogs of the zeolites sodalite, analcime and natrolite, the last not hitherto reported in an ALPO composition.
- G02 - Nanocrystallization of Amorphous Nanoporous Carbon Derived from the Pyrolysis of Polyfurfuryl Alcohol
C. L. Burket, P. Ayyappan, K. McNamara, R. Rajagopalan, H. C. Foley
Abstract: Intimate knowledge of the atomic structure of a non-graphitizing carbon is necessary to understand its thermal stability and resistance to graphitization. Previously we have noted the unexpected low temperature nanocrystallization of a non-graphitizing amorphous carbon in the presence of alkali metals, excluding lithium. This intriguing result caused us to explore the reorganization mechanism in detail by examining the high temperature nanocrystallization of the same carbon in the absence of alkali metal. The connection between polymer cross-linking and the structure of the pyrolyzed carbon is also examined. We have studied the evolution of nanocrystalline domains between 800 °C and 2000 °C. Orientation of nanocrystalline domains significantly increases the oxidative thermal stability of the carbon. Although long range ordering is not detectable by XRD below 2000 °C, TGA and HRTEM clearly demonstrate reorganization at temperatures as low as 1200 °C.
