Brent Thomas Fultz - US grants

This is a Presidential Young Investigator Award to Dr. Fultz, whose research interests include electron microscopy, diffusion, and ordering kinetics in metallic alloys. Computer simulation of atomic relaxation in nonequilibrium metals, experimental Mossbauer spectroscopy, and x-ray analysis of rapidly-solidified alloys are part of his research program. The emphasis is on the kinetic paths that nonequilibrium metal alloys take as they progress towards equilibrium.

This research project is directed in two major thrust areas (i) processing of metal alloys and (ii) processing of semiconductor materials. A component connecting both of these areas is simulation and theory work aimed at predicting materials properties. The metal processing research employs ion beam mixing, shock consolidation, mechanical alloying, and synthesis of layered and metastable materials. The semiconductor processing research employs epitaxial growth on Si and GaAs, ion implantation, nucleation and growth on new phases such as amorphous carbon. The use of sophisticated electron microscopy apparatus is central to the research projects. Better understanding of the influence of interfaces, surfaces and grain boundaries on materials properties is a primary goal of this reserach.

Harry Atwater Abstract The acquistion of a quantitative high-resolution video imaging system is proposed. The system will be used in conjunction with existing transmission electron microscopes for (i) atomic-scale imaging of thin films and nanoparticles, (ii) energy-filtered imaging of thin films and nanoparticles, (iii) quantitative electron diffraction nmeasurements,a nd (iv) facilitating the teaching of electron microscopy and microanalyis of materials. ***

This research involves an experimental investigation of the thermodynamics of nanophase materials. Mechanical attriting is the technique employed to process various nanophase metallic systems. Associated effects of environmental factors during attriting are determined. Both positive and negative heats of mixing are represented in the materials' systems proposed. Grain boundary segregation tendencies are noted and related to the potential for grain growth during low temperature annealing and consolidation. Several experimental characterization methods are proposed to examine the chemistry on a nanoscale, including calorimetry, electron energy loss spectrometry (EELS), Mossbauer spectrometry, and small angle X-ray scattering (SAXS). %%% Nanostructured materials are a class of new materials whose properties are expected to be markedly changed by the consequences of the fine structure. This research explores factors affecting the stability of such materials.

9415331 Fultz In this research, Mossbauer diffraction is applied to powder structure characterization. Hyperfine interactions cause the scattering factor of an 57iron atom to change strongly for slightly different gamma ray energies. This could provide a basis for unique chemical selectivity in diffraction experiments. The chemical selectivity could be used to tune a gamma ray to the specific chemical environment of an 57iron atom and determine a specific diffraction pattern from that chemical environment alone. The experimental work attempts to measure the face-centered cubic and simple cubic diffraction patterns from two iron sites in DO3-ordered 57iron aluminide. Preliminary experimental results have been encouraging and have provided practical parameters for the this work. If these first experiments are successful, measurement will be made on the arrangements of antisite atoms in partially-ordered 57iron aluminide and in a B2 57iron - rhodium. In a parallel effort, the timing capabilities of the position-sensitive detector will be tested. If the detector can be operated with both time and positron resolution, later experiments may be performed at a synchrotron radiation facility. %%% To date, materials science has relied heavily on x-ray, electron, and neutron diffraction to characterize the structure of powders. Mossbauer diffraction, which occurs by scattering of gamma rays from nuclei, is explored as an additional useful technique for powder diffractometry. ***

9816617
Fultz

For 35 years, almost all applications of the Mossbauer effect in materials science have utilized its capabilities as a spectroscopy. Many investigators have identified and quantified spectral components from different crystallographic phases or chemical environments of the Mossbauer atom. Mossbauer scattering can also be coherent, however, enabling its use for a fourth type of diffraction experiment on materials (the other three being X-ray, electron, and neutron diffraction). The unique feature of Mossbauer diffraction is its spectroscopic selectivity. This program studies disorder in metallic alloys by the chemical environment selectivity of Mossbauer diffraction. The chemical sensitivity of Mossbauer spectrometry is used to select an atom in a particular chemical environment, and a diffraction pattern is then measured from atoms having that particular environment. An area detector based on a CCD camera is now available, and funds are requested for a new type of gas-filled area detector developed by a group in Frankfurt. Studies are on alloys of 57Fe3Al and 57FeRh having imperfect chemical order. In these studies, measurements are made of the spatial periodicities of irregular chemical environments (Fe sites other than the Fe sites of the DO3 and B2 ordered structures). With the Frankfurt detector, it should be possible to measure diffraction patterns from different Fe environments in a quasicrystalline Al-Cu-Fe alloy. If detector issues are resolved, some synchrotron experiments on Mossbauer diffraction will be performed during the course of this research. In the last couple of years, advances at third generation synchrotron sources have made it possible to measure nuclear excitations accompanied by phonon excitations. These inelastic spectra can be used to obtain the phonon partial densities of states of Fe atoms in the material. This work on inelastic nuclear resonant scattering will show how vibrations of Fe atoms contribute to the vibrational entropy of different alloy phases. Inelastic nuclear resonant scattering recently showed that the vibrational entropy of Fe3Al depends almost entirely on chemical short-range order (as opposed to long-range order). This proposal describes measurements to be made on how the vibrations of Fe atoms depend on chemical order in Pt3Fe and FeRh, how Fe vibrations depend on point defect concentrations in FeAl, and how Fe vibrations differ for quasicrystalline and crystalline Al-Cu-Fe.
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After approximately 25,000 publications on Mossbauer spectrometry studies of materials, the Mossbauer effect is well established and well suited for many studies in materials science. Its extension to inelastic nuclear resonant spectrometry should be useful for studies of atom vibrations in small samples such as thin films for which neutron methods are not practical. The complementary nature of the three diffraction methods (X-ray, electron, and neutron) has sustained their widespread use in materials science. There is room for a fourth method of Mossbauer diffractometry.

0076512
Johnson

This an award is for the acquisition of a modern sample preparation equipment to prepare with minimum damage specimens of complex materials for transmission electron microscopy (TEM). The equipment will provide new opportunities and advance the current capability of the TEM facility at Caltech acquired earlier with NSF support. The new sample preparation equipment will allow reliable and controlled specimen preparation, and the reduction of specimen contamination in the electron microscope. It will facilitate investigations of micromechanisms of deformation in bulk metallic glasses, interfacial phenomena in composites and other fundamental properties of a wide range of materials. The equipment will see heavy use for a broad range of materials investigations currently and for materials research at Caltech over the next decade.
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This an award is for the acquisition of a modern sample preparation equipment to prepare with minimum damage specimens of complex materials for transmission electron microscopy (TEM). The equipment will provide new opportunities and advance the current capability of the TEM facility at Caltech acquired earlier with NSF support. The new sample preparation equipment will allow reliable and controlled specimen preparation, and the reduction of specimen contamination in the electron microscope. It will facilitate investigations of micromechanisms of deformation in bulk metallic glasses, interfacial phenomena in composites and other fundamental properties of a wide range of materials. The equipment will see heavy use for a broad range of materials investigations currently and for materials research at Caltech over the next decade.
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The objective of this research is the development of reliable and accurate techniques for the determination of structural and vibrational properties of complex materials. A major goal of the study is to investigate the disorder in metallic alloys with the unique chemical environment selectivity of Mossbauer diffractometry. The unique feature of the technique is its capability to select iron atoms in a particular chemical environment, and obtain a diffraction pattern from those iron atoms alone. With the new Mossbauer diffractometer, it is possible to measure the periodicity of an irregular chemical site of iron atoms with 3 aluminum first-nearest neighbors in ordered FeAl. Studies will also be made on alloys of FeRh and PdFe with emphasis on investigating the inelastic spectra to obtain the phonon partial density of states of iron atoms. Extreme high pressures using diamond anvil cells will be used to investigate the influence of pressure on interatomic force constants. In a different style of experiment, the Mossbauer diffractometer will be used to study the spatial scale of thermal relaxations in magnetic nanoparticles. A specific experiment on thermal relaxations on hematite nanoparticles will be developed over the course of the work. Such results show how the vibrational entropy of alloys depends on interatomic separations, and can elucidate the reasons for the P(V,T) equation of state of iron alloys. The broader impact of the proposed work lies not only in developing reliable techniques for the structural determination of complex materials but also in obtaining detailed information on interactions in solids at the atomic level.

Thermodynamics and atom arrangements are at the core of materials science, and the proposed work will apply new experimental methods for studying them. The methods are specialized, but have unique capabilities for resolving a high level of detail about the structure and dynamics of materials. The structure of materials is the focus of the work on Mossbauer diffractometry. The entropy of materials is the focus of the work on inelastic nuclear resonant scattering. The basic issues in diffraction and scattering are also of broad academic interest in materials science.

The Spallation Neutron Source (the "SNS"), under construction in Oak Ridge, Tennessee with a budget of $B1.411, is the world's largest science construction project. In 2006 it will start to produce intense beams of neutrons to be used as probes of materials. The instruments that control these beams, and detect the neutrons scattered from specimens, are state-of-the-art. Neutron scattering experiments performed at the SNS will produce data of unprecedented detail on the positions and motions of atoms and spins in materials, molecules, and condensed matter. Under the IMR-MIP program at the NSF, a conceptual engineering design effort is being supported to build software for the analysis of data from the SNS and other neutron facilities in a system called DANSE - distributed data analysis for neutron scattering experiments. The DANSE project includes a central resources activity, and subprojects in the different subfields of neutron scattering science at different institutions around the U.S. The lead institution is the California Institute of Technology. The scientific subprojects are led by faculty at Michigan State Univ. (diffraction), at Iowa State Univ. (engineering diffraction), the University of Maryland (reflectometry), the University of Tennessee (small-angle scattering), and Los Alamos, and Caltech.
DANSE uses a new software architecture based on the data flow paradigm. Analysis is performed with reusable software components that can be connected across a network using standardized data streams. Components are integrated into a coherent interpretive framework using the open source language Python so that custom analysis procedures can be constructed easily at runtime. The architecture enables high performance computing on distributed resources and opens access to the future cyber infrastructure of grid-based computing. DANSE provides an unprecedented opportunity to merge data analysis, theory, and simulation into a uniform computing environment. The goals of the DANSE project are to build a software system that 1) enables new and more sophisticated science to be performed with neutron scattering experiments, 2) makes the analysis of data easier for all scientists, and 3) provides a robust software infrastructure that can be maintained in the future.


The Spallation Neutron Source (the "SNS"), under construction in Oak Ridge, Tennessee with a budget of $ 1,411,000,000, is the world's largest science construction project. In 2006 it will start to produce intense beams of neutrons to be used as probes of materials. The instruments that control these beams, and detect the neutrons scattered from the specimens under study, are state-of-the-art. Neutron scattering experiments performed at the SNS will produce data of unprecedented detail on the positions and motions of atoms in materials. The raw experimental data acquired with these instruments are not simple to interpret, and new software is required to transform the data into useful forms. Beyond such data reductions that are available today, there is an opportunity to interpret data using several major advances in computational materials science that have occurred over the past decade. Under the IMR-MIP program at the NSF, a conceptual engineering design effort is being supported to build a software system called DANSE - distributed data analysis for neutron scattering experiments. The DANSE project includes two parts. The first is a software engineering effort to build a framework that permits the interoperability of modular software components. The second is an effort by scientists
at different institutions around the U.S. to develop the software components needed for data analysis for the different subfields of neutron scattering research. The lead institution is the California Institute of Technology. The scientific subprojects are led by scientists at Michigan State University, Iowa State University, the University of Maryland, and University of Tennessee. The goals of the DANSE project are to build a software system that 1) enables new and more sophisticated science to be performed with neutron scattering experiments, 2) makes the analysis of data easier for all scientists, and 3) provides a robust software infrastructure that can be maintained in the future.

This is an award for the construction of a Distributed Data Analysis for Neutron Scattering Experiments (DANSE) at the Spallation Neutron Source. It is supported by the Instrumentation for Materials Research- Mid Scale Instrumentation project program in DMR, the Office of Multidisciplinary Activity in the Mathematical and Physical Sciences Directorate, as well as the Chemistry division in DMR and the Chemical Transport Division in Engineering Directorate. The goals of the DANSE project are to build a software system that 1) enables new and more sophisticated science to be performed with neutron scattering experiments, 2) makes the analysis of data easier for all scientists, and 3) provides a robust software infrastructure that can be maintained in the future. The DANSE project was prompted by the development of the Spallation Neutron Source (http://www.sns.gov) (SNS). In 2006 the SNS will start to produce intense beams of neutrons to be used as probes of materials, molecules, and condensed matter. Neutron scattering experiments performed at the SNS will produce data of unprecedented detail on the positions and motions of atoms and spins in materials, molecules, and condensed matter. The raw experimental data acquired using the SNS instruments are not simple to interpret, and new software is required to transform the data into useful forms. Using several major advances in computational materials science that have occurred over the past decade the DANSE project will provide new data reduction and interpretation capabilities beyond what are available today. The DANSE project includes a central resource activity centered at Caltech, and 5 components based at different institutions: diffraction led by Simon J.L. Billinge of Michigan State Univ., engineering diffraction led by Ersan Ustundag of Iowa State Univ. , reflectometry led by Paul Kienzle of the Univ. of Maryland, small-angle scattering led by Paul Butler of the Univ. of Tennessee, and inelastic scattering led by Frans Trouw of Los Alamos with B. Fultz.
Information about the project is available at http://wiki.cacr.caltech.edu/danse/index.php/Main_Page
The project is helping to organize the neutron scattering science community in the U.S., and has generated worldwide interest. DANSE is a natural application for grid-based computing, and the layered design of the DANSE framework was planned for migration to the TeraGrid, or a similar future cyber infrastructure. The DANSE framework could be adapted for data analysis in other fields of science. An outreach effort has been planned as collaboration with education professionals at Iowa State University.

DMR ? 1041426
Fultz, Brent T.

This award to Californaia Institute of Technology is from the Chemistry Division and the Division of Materials Research in The Mathematical and Physical Sciences and the Office of Cyberinfrastructure. The funds support entitled ?Workshop on Computational Scattering Science 2010? and will be held on July 6-9 at Argonne National Laboratory. The Workshop is to identify, and to reassess opportunities to connect the fields of scattering science and computational science. The goal is to develop a roadmap showing how modern computing can advance scattering science, to offer new opportunities for scientific discovery, and to identify opportunities. The workshop will also develop ideas to organize future software development, manage maintenance, upgrades, and user support at the Nation?s neutron and x-ray facilities. The outcome of the workshop will be a report that will critically assess strengths, weaknesses, and cost-effectiveness and present possible paths forward. The workshop will also identify the role of computational scattering science in education, and in promoting public awareness of scattering research in the U.S. Lowering the barrier for entry into scattering research will also be discussed. Finally, the workshop will help in the formation of a nucleus of a community for computational scattering science, and such a community is needed for optimizing the future effort in this field.

SUMMARY

The Office of Cyberinfrastructure, Division of Materials Research, and Chemistry Division contribute funds to this award.

This award supports a conceptualization effort to design a Sustainable Software Innovation Institute to elevate the level of scientific computing in X-ray and neutron scattering science. This conceptualization project will define the priorities of users and facilities to serve a significant fraction of the community of 14,000 annual users of X-ray and neutron scattering facilities in the U.S. The Institute aims to adapt modern methods of computational materials science to predict scattering from materials. It would incorporate these software tools into workflows for scattering scientists, giving them new pathways to scientific discovery.

Since 1980, the performance per dollar of computer hardware has increased by a factor of 100 every decade. Over the same time period, this million-fold improvement has been closely matched by the increased brilliance of X-ray sources, and in the past decade the performance of neutron sources has increased by a factor of ten. These improvements should be multiplied by comparable factors to account for improvements in software and methods of computational science, and for major improvements in optics and detectors for X-rays and neutrons. These enormous advances in computing and in scattering have occurred independently. Today there are exciting opportunities for combining them to do new science, and there is a growing body of work in computational scattering science that does so. Today this is only a small fraction of the work done by users of the synchrotron and neutron sources in the U.S., but it accounts for a disproportionately large fraction of high impact publications.

The conceptualization process will shape and assess envisioned activities of the Institute in the areas of workflow, uncertainty quantification, new avenues for discovery, and education.

An important activity of the Institute will involve developing new computational workflows that open channels for discovery in scattering science. This can be as direct as offering a common environment for comparing results from experiment to results from computational materials science. Computing also facilitates the combined analysis of information from different types of experiments, linked by an underlying model of the structure and dynamics of a material. Such a combined approach requires the assessment of uncertainties in the model using mathematical methods that are not yet standard practice in scattering science. This conceptualization project will develop a path to obtaining appropriate uncertainty analysis tools for a computationally enabled scattering science.

Workflows that include calculations of the structure and dynamics of materials can allow experimental results to be interpreted on a more fundamental level, letting scientists explore properties that are not measured directly by experiment opening new avenues to discovery.

This project supports aspects of the Materials Genome Initiative.

The Institute will bring materials simulation to train the next generation of scattering scientist. The Institute aims to broaden participation, particularly of women in computational science.

PART 1: NON-TECHNICAL SUMMARY

With increasing temperature, metallic iron expands a little bit, and it becomes less stiff. These properties of thermal expansion and thermal softening are similar in steels (which are mostly iron), and are important for the engineering of machines, infrastructure, or devices of any size. Perhaps surprisingly, in 2019 it is not known how to calculate the thermal expansion of iron (or its thermal softening). Some of the parts of the story, and some relations between them, are known in principle. For example, atoms vibrate more vigorously with increasing temperature, and small details about atom vibrations make a big difference in how iron expands and softens. A big challenge for iron, however, is that its magnetism also changes with temperature. The vibrations of iron atoms are affected by the change in magnetism, and proper calculations of these effects are only emerging today. This project will complete this story by experiments. It will measure the vibrations of iron atoms, obtaining the full spectrum of their vibrational frequencies. Measurements will be performed at temperatures from -258 C to +800 C, simultaneously at pressures varying from 1 atmosphere to 90,000 atmospheres. Obtaining high temperatures and high pressures simultaneously and precisely is the technical challenge. It will be undertaken with diamond anvil pressure cells. The vibrational spectra of very small samples (less than 0.1 mm in size) in the pressure cells will be measured with synchrotron radiation at the Advanced Photon Source at the Argonne National Laboratory. The PI expects to learn how the change in magnetism with temperature and pressure alters the thermal expansion of iron. Other materials such as Invar may be studied in a similar way if time permits. Some of the concepts about atom vibrations, and how they influence the thermodynamics of materials, are appropriate for video content. Some public video instruction is already available. It will be organized, and new content added, to make it useful for teaching. A high school intern will be mentored during the summer, and the PI will also help support Girls Who Code to teach computer programming to underrepresented students in Pasadena middle schools.


PART 2: TECHNICAL SUMMARY

This experimental project on bcc (alpha) iron will obtain thermodynamic quantities underlying the equation of state V(T,P) by measuring the entropy of vibrations at different combinations of P (pressure), T (temperature), and V (volume) in the sample. Diamond anvil cells are required to obtain the pressures, and the sample in the pressure cell must be heated or cooled. The main effort will be inelastic nuclear resonant x-ray scattering (NRIXS) of 57Fe, with samples at simultaneous pressure and temperature. NRIXS can determine the phonon density of states and hence the vibrational entropy. Simultaneous measurements of nuclear forward scattering will show changes in the magnetism, and diffraction will give the specific volume. Thermodynamic relationships can give the thermal expansion, beta, and the temperature dependence of the bulk modulus, dB/dT, but now the individual contributions from vibrations, magnetism and electrons can be identified separately, and usefully compared to the total entropy known from calorimetry. Both beta and dB/dT are interesting for iron because they should be altered by interactions between atom vibrations and magnetism. Support from ab initio theory is proposed through a collaboration. The PI now teaches his course on phase transitions in materials using a flipped classroom pedagogy. As part of this work, he will curate and develop video content to convey essential concepts in entropy, free energy and phase transformations in materials for distribution on public video platforms such as YouTube. A high school intern will be mentored during the summer. The PI will also support Girls Who Code to teach computer programming to underrepresented students in Pasadena middle schools.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.