Takeshi Egami - US grants

This proposal involves research on the nature of the structure of quasicrystals and metallic glasses that can form quasicrystalline structures upon annealing. Conditions for formation of quasicrytals will be ascertained from analysis of structural relaxation occurring in the amorphous state and subsequent transformation into the quasicrystalline state. Experimental techniques to be applied include differential anomalous X-ray scattering, neutron scattering, energy dispersive X-ray and synchrotron radiation diffraction. Several metallic glass alloy systems will be studied that show tendencies toward possible quasicrystalline structure formation. Dr. Egami has an outstanding research record and the facilities at the University of Pennsylvania are excellent for performing the proposed program. This research was previously supported by NSF Grant DMR-8318816.

Partial funding is provided to support purchase of a Huber goniometer and to upgrade X-ray detection equipment used for thin film studies. The equipment will allow high resolution X-ray scattering studies of order and structure in various types of thin films, including thin liquid crystalline films, ceramic and superconducting films and amorphous magnetic films.

This program explores the defect structure of quasicrystals, superconducting oxides, and amorphous alloys using the technique of atomic pair distribution function analysis (PDF). The PDF method has been employed primarily for amorphous solids and liquids and is now being used in the examination of non-periodic atomic displacements in more ordered solids. The PDF method is refined further in this research, which examines the statistical noise, lattice dynamics, and techniques for improved accuracy in the differential anomalous x-ray scattering experiments. The main focus of the grant is on developing understanding of defect structure in the above materials, which have high incidence of atoms which deviate in position from their average sites.

9523076 Egami This grant supports the Ninth International Conference on Liquid and Amorphous Metals. The conference provides a forum for bridging basic and applied aspects in a variety of materials ranging from composites and nano-materials to amorphous and liquid semiconductors. About 300 participants from academic, industrial and government laboratories are expected. The Conference takes place in Chicago, Illinois, from August 27 to September 1, 1995. The conference highlights advances in liquid and amorphous metals, encompassing noncrystalline semiconductors and molten salts and the conference proceeding will be published. The following topics will be covered in the conference: liquid and amorphous metals and alloys; metal-nonmetal transitions; liquid and disordered semiconductors; clusters; composite materials; quasicrystals; metal/molten salt mixtures. Atomic structure determined by x-ray, neutron and electron diffraction; dynamics, electrical transport and electronic, magnetic, optical and thermodynamic properties, are addressed, including theoretical and computational as well as experimental approaches. Results obtained from new techniques, taking full advantage of recently commissioned synchrotrons, pulsed neutron sources and high-flux reactors to explore domains and properties previously not accessible, are emphasized. %%% Highlighted topics include new structural materials and applications in energy conversion, electronics, optics/electro-optics, and waste storage. ***

This instrument development award from the Instrumentation for Materials Pesearch program allows the to the university of Pennsylvania to upgrade the Neutron Powder Diffractometer (NPD) at the Los Alamos Neutron Science Center (LANSCE) to a world-class high-resolution diffractometer for materials research and education. With this upgrade the beamline will have a unique capability for simultaneous high-Q (momentum transfer) crystallographic analysis as well as the real-space atomic pair-density function (PDF) analysis. The data acquisition rate at high angles will increase by a factor of five by adding a large backscattering detector module, upgrade computers and install a beam-chopper. The upgrading of NPD will have wide-ranging educational impact. This fivefold increasing in the data collection rate will create more research opportunities for graduate students from five different institutions. Graduate students will also participate in the calibration task and development of software, and thus acquire precious experience of setting up a large instrument at a national facility. This project will significantly contribute to increasing the university users.
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The power of pulsed neutron powder diffraction method in materials research is widely recognized. It is capable of determining the atomic structure of complex materials with high accuracy, thus providing basic information vital to materials science and technology. This award will allow the University of Pennsylvania to carry a very cost-effective upgrade of the Neutron Powder Diffractometer (NPD) at the Los Alamos Neutron Science Center (LANSCE) to a world-class high-resolution diffractometer for materials research and education. This will allow a dramatic improvement of the data collection rate, by a factor of five. Upgrading this beamline will have significant impact on graduate education and training at five different institutions. This will help contribute to overcome a critical shortage of trained scientists in neutron scattering in the US. The IMR award is significantly leveraged using funds from LANSCE.
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0118222
Egami

International Conference on LOCAL AND NANOSCALE STRUCTURE IN COMPLEX SYSTEMS will be held September 16-21, 2001 in Santa Fe, New Mexico, USA. The purpose of this meeting is to discuss how the nanoscale arrangements of atoms in solids and molecules determine the properties of complex systems, from experimental as well as theoretical perspective. Examples of complex systems include strongly correlated electron systems such as superconducting cuprates and magnetostrictive (CMR) manganites, heavy fermion metals, relaxor ferroelectrics, catalysts, polymers and other soft or molecular compounds, and proteins.
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The subject of this conference is at the cutting edge of condensed matter and materials physics. Graduate students and postdoctoral fellows will be greatly stimulated and learn from attending this conference. We plan to spend 60 % of the grant on students and postdoctoral fellows who do not have other means of support. The rest will be spent for inviting young and promising researchers who will not be able to attend the conference without support.

The research goal of this project is to elucidate the remarkable structure-properties relationships for electronic complex oxides such as high-temperature superconductivity (HTSC) through the study of their local structure at a nanometer scale, and to provide the scientific basis for developing new materials with better properties. This will be achieved principally through neutron and x-ray scattering with the atomic pair-density function (PDF) analysis, applied for static and dynamic structures.

The broader impacts include the improvement the PDF method and further demonstration of its power as an alternative method of structural characterization. Products of this project, the improved software for the PDF determination, will be made available to general users. This will benefit the field of nanotechnology, catalyst research, ceramics research and materials science in general.

With support from the Chemistry Research Instrumentation and Facilities (CRIF) Program in the Division of Chemistry and the National Facilities Program in the Division of Materials Research, Linda Magid of the University of Tennessee in Knoxville is organizing a 3-day workshop at Florida State University. The workshop has the following three goals:

a) To inform the chemistry and chem-bio communities of opportunities at the Spallation Neutron Source (SNS) and at the Center for Nanophase Materials Science (CNMS), both at Oak Ridge National Lab (ORNL).
b) To query the community re: needs for instrumentation and sample environment development, among others.
c) To develop concept teams that would be responsible for developing science cases and funding proposals for instrumentation, sample environments, supporting lab facilities, best practices for education of new users, and fellowship programs.

This award will provide travel support and subsistence for 50 grad students, postdocs and/or junior faculty as well as 30 invited speakers. The Joint Institute for Neutron Sciences (JINS), and the National High Magnetic Field Laboratory at Florida State University are also providing partial support.

Beamlines at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) should be operational in 2006. Opportunities exist for scientific advances with neutron scattering and spectroscopic investigations there by chemists and by biologists working at the chemistry-biology interface. However, the number of active neutron users in the US among these communities is woefully small. This workshop will provide an opportunity to attract and inform potential new users in these communities.

This project is a workshop on Sample Environments for Neutron Scattering Experiments (SENSE). It is action-oriented, with the goals of (1) exploring the science drivers that impact issues concerning the development of advanced sample environments for neutron scattering - primarily focused on the Spallation Neutron Source (SNS) - and (2) developing a roadmap to address these needs. Scientists who are new to the use of neutron scattering are encouraged to attend a tutorial session at the beginning of a companion NSFCHEMBIO workshop targeted at the chemistry and biology communities. The SENSE workshop proper begins with a plenary session to consider the science case for advanced sample environments; that is, environments that provide control of the sample temperature, pressure, magnetic-field environment, and chemical environment. The workshop continues with a series of parallel oral presentations on scientific research and on the technical aspects of leading sample environments worldwide. This is followed by user-focused interactive sessions. The SENSE workshop also includes a tour of the NHMFL and joint sessions with the parallel NSFCHEMBIO workshop. Because the SENSE workshop is intended to launch the development of a science-driven roadmap for national sample-environment initiatives, it concludes with summaries by the workshop section chairs and "concept teams" and the identification of follow-up action items. In addition to engaging experts in the field, the SENSE workshop is involving the broader community, specifically including graduate students, postdocs, and junior faculty members, as well as scientists who are new to the technique of neutron scattering. Two of the plenary lecturers are women, and the organizers are also reaching out to several HBCUs.

Neutrons with low energies are useful probes of the properties of matter, being especially responsive to structural and dynamical properties on spatial scales ranging from atomic dimensions to micro-meters. These are scales characteristic of, for example, polymers, grains in metals and alloys, and living cells. Neutrons also provide unique probes of magnetic properties on similar scales. The properties of materials depend upon conditions in their environment, however. For example, the ambient temperature, pressure, and magnetic-field environment all affect the properties of physical materials. This is obvious near the melting or freezing point of a substance. Similarly, the properties of living cells are affected by temperature, pressure, and the chemical environments in which they find themselves. Up to this point, however, it has not generally been possible to provide sample environments that allow wide-ranging control of such parameters. The purpose of this workshop is to explore the needs of the various scientific communities for advanced sample environments and to develop a plan of action to enable them to be realized. This project is especially timely now, as the Spallation Neutron Source (SNS) approaches completion at Oak Ridge National Laboratory in 2006.

Nearly all materials properties are determined by electrons close to the Fermi level, usually within 100 meV. In order to probe the behavior of electrons in this energy range, one needs to employ spectroscopy with ultrahigh resolution. This project entails the acquisition of an ultrahigh-resolution photoemission spectrometer of the Scienta type, which offers the best resolution that is currently achievable. This instrumentation will be used to investigate the electronic states in a wide variety of advanced electronic materials, including complex transition metal oxides, thin film nanostructures, organic superconductors, and atomic-wire arrays. Coupled with other spectroscopic methods, such as inelastic neutron scattering for probing spin and lattice excitations, and optical spectroscopy and Electron Energy Loss Spectroscopy for charge dynamics, it will enable researchers to unravel the highly complex entanglement of the spin, charge, and lattice degrees of freedom in these exotic materials. The new instrumentation will be based on campus, not at the synchrotron, so that students and faculty can have easy access and copious amounts of high quality photoemission time. The proposed science and new infrastructure will provide an excellent setting for the education and training of internationally competitive students and postdocs.


Nearly all materials properties are determined by electrons close to the Fermi level, which represents the highest occupied energy level. Examples include electrical conductivity, magneto-resistance, superconductivity, and magnetism. In order to understand these important materials properties, one should probe the electrons near the Fermi level with ultrahigh resolution spectroscopy. From the late 1980s, Angular Resolved Photo-Emission Spectroscopy has been intensively applied to unravel the origins of superconductivity in high-temperature superconductors. In recent years the resolution of photoemission experiments has improved so much that electrons within a fraction of a milli-electronvolt around Fermi level can now be distinguished. Many of these potentially prize-winning studies have been published in highly prestigious journals because the ever increasing resolution unraveled novel properties that challenged the community and triggered new discovery. This project entails the acquisition of the world's best ultrahigh-resolution photoemission apparatus for the University of Tennessee. It will be used to study a wide variety of advanced electronic materials, including complex transition-metal oxides, thin film nanostructures, organic superconductors, and atom-wire arrays. A key aspect of the proposed research activities is that the powerful capabilities of this instrument will be combined with the local, complementary expertise and capabilities in neutron scattering and materials synthesis, thus providing researchers in East Tennessee with a competitive edge. The new instrumentation will be based on the Knoxville campus, not at a national synchrotron facility, so that students and faculty can have easy access and copious amounts of high quality photoemission time. The proposed science and infrastructure will also be accessible to the African American and Hispanic minority-student population at Florida International University and provide an excellent setting for the education and training of internationally competitive students and postdocs from diverse backgrounds.

The project entails cooperative research of complex ferroelectric oxides between the group from the University of Tennessee at Knoxville, USA, and the group from A. F. Ioffe Physico-Technical Institute, Russian Academy of Science, St. Petersburg, Russia. It addresses some of the most important unsolved and current problems in the field of ferroelectric materials. In particular it aims at 1) identification of the atomistic origin of a relaxor behavior in Pb-based magnesium-niobate perovskite, 2) examination of dynamic and structural instabilities leading to phase transitions in Na-based niobate perovskite, and 3) elucidation of the structural factors resulting in a relaxor transition in solid solutions of Na niobate perovskite. Advancing this knowledge would greatly facilitate development of lead-free relaxor piezoelectric materials. The main reason hindering the understanding of the atomistic mechanism of the relaxor behavior is strong displacive and chemical disorder in the local atomic structure which frustrates conventional structural and dynamical studies.
The project will leverage complementary research expertise of the two groups in applying neutron and X-ray scattering to study lattice dynamics and local atomic structure of the complex ferroelectrics. The US group will focus on powder samples and local structural methods whereas Russian group will be additionally examining single crystals. The local atomic structure will be studied by the atomic pair distribution function method that has proven to be very effective in determination of atomic displacements and disorder. Complementary detailed studies of lattice dynamics (phonons) in single crystals will be performed by the Russian researchers. The emphasis will be placed on understanding physics behind the giant dielectric response of lead-free relaxor-like solid solutions and critical dynamics and structural instabilities.
The project will have broad impact for society and industry by advancing knowledge for the development of environmentally benign piezoelectric ceramics. Traditional materials, based on lead can create health hazards. The results will be quickly disseminated to contribute to education and stimulate research and development. The collaborative framework of this project will allow training of graduate and undergraduate student in new experimental techniques and involve them into science and technology of ferroelectric materials. This approach will enhance quality of education and promote new ideas through the exchange visits and collaborative experiments.

0959465
Kelton
Washington U.

Technical Abstract:
This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

A team of scientists and students from Washington University in St. Louis, Iowa State University in Ames, Iowa, the University of Tennessee in Knoxville, Tennessee, and the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, will develop a novel facility for neutron scattering studies of high temperature liquids (NESL, Neutron ElectroStatic Levitation). The liquids will be levitated in high vacuum using electrostatic levitation, thus avoiding container contamination. Liquids and glasses are probably the least understood phases of matter, with many outstanding questions concerning their physical properties and atomic structures. An understanding of how they crystallize and, in some cases, become glasses with cooling is incomplete. Furthermore, novel phase behavior and phase transitions in liquids at temperatures below their melting temperatures (supercooled) are largely unexplored. Since most elements are liquids only at elevated temperatures and react strongly with container materials, experimental studies of their structures and properties are difficult or impossible to accomplish. NESL will allow structural and dynamical studies of high-temperature liquids, both above and below their equilibrium melting temperatures. NESL will be optimized for elastic and inelastic neutron scattering studies, and used on the recently completed SNS, the world's most intense pulsed accelerator-based neutron source. NESL will have a tremendous impact on fundamental and basic research, and will serve as a catalyst for expanded national and international collaborations. It will allow pioneering studies of evolving short and medium range order in and liquid dynamics, addressing fundamental questions that have profound applied as well as basic interest. When coupled with specialized ESL chambers at Washington University and Iowa State University, NESL will create a unique opportunity for coordinated structural and property studies of solids, liquids and metastable phases, for sample temperatures up to 3000K.

Layman Abstract:
This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

While liquids and glasses have been subjects of study for millennia, they are probably the least understood states of matter. Key questions center on their structure at an atomic level, and how this structure determines their properties and their ability to change to other states. For example, in 1721, Fahrenheit discovered that under proper conditions liquids can be held at temperatures below their melting temperature without crystallizing (a common example of crystallization is when liquid water turns into ice). Surprisingly, almost 300 years later we still don't completely understand the origin of this resistance to form the crystal phase, nor do we understand the atomic processes that occur during crystallization and their relations to the liquid atomic structure. In addition to discontinuous transformations like crystallization, if they are cooled fast enough, liquids can also solidify by a continuous process to become a glass, where the atoms are frozen into the structure of the liquid. While cooling through the glass transition has been a technique commonly used by glassblowers for centuries to make intricate and beautiful glass objects, the process is poorly understood, claimed to be the most challenging unsolved problem in the physics of materials. Neutron scattering studies of liquids offer a unique way to unravel these and related questions. However, a key problem is that the liquid cannot be held in a container, since contact with the container will induce crystallization before measurements of the supercooled liquid (i.e. liquid below its melting temperature) can be made. Building on their successes in the development of techniques for x-ray scattering studies of liquids, a team of scientists at Washington University in St. Louis, Iowa State University in Ames, Iowa, the University of Tennessee in Knoxville, Tennessee, and the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, will develop a facility that is unique in the world, to be used at the SNS for neutron scattering studies of levitated liquids, thus avoiding the need for a container. In addition to their importance to basic understanding, the capabilities that this facility offers will have profound practical technological importance, leading to refined methods for materials development.