Condensed-Matter and Materials Physics The Science of the World Around Us (2007) / Chapter Skim
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11 Tools, Instrumentation, and Facilities for Condensed-Matter and Materials Physics Research
11 Tools, Instrumentation, and Facilities for Condensed-Matter and Materials Physics Research
Pages 193-238
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As CMMP researchers seek to answer fundamental questions about materials, they will continue to design 193
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Likewise, techniques designed to synthesize high-quality materials with precisely controlled structures underpin many great CMMP discoveries. By pushing the boundaries of materials fabrication and measurement forward, experimental CMMP researchers have uncovered new phenomena that were often unanticipated.
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There is a need for keeping the infrastructure supporting CMMP research at universities up to date and for providing modern instruments for the training of the next generation of researchers. Instrumentation in CMMP Research CMMP researchers have a track record of developing new measurement tools that have enabled advances not only within CMMP, but also in other areas that encompass the physical, chemical, biological, and medical sciences.
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of neutrons and the efficiency with which the scattered neutrons are detected are key factors that determine the performance of a neutron source. The third-generation neutron sources (for example, the Spallation Neutron Source [SNS]
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. With the use of tomographic techniques, information about the interior of samples can now be learned without the need to section them destructively for analysis with transmission electron microscopy (TEM)
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Computation in CMMP Research As the materials and phenomena of interest have become increasingly com plex, computation has emerged as an essential tool in the process of interpreting experimental data and analyzing theoretical models. Over the past decade or two, computational CMMP has developed fully into a branch of study in its own right, on a par with experimental and theoretical CMMP.
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Figure 11.1 shows an example of the rich variety of ground-state orderings that have been observed in models of the cuprates with the DMRG method. Methods for the direct solution of the underlying quantum mechanical equa tions allow quantitative, material-specific, first-principles prediction of structure and properties.
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The direct solution of the underlying quantum mechanical equations also plays a key enabling role in the design of new materials. In this work, the target is particular structures and properties, requiring the solution of the "inverse problem" to find a corresponding material.
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Similar principles can be applied to the design of heterogeneous materials and devices. Much of the important physics in materials systems takes place at length scales well beyond which fully first-principles methods are practical.
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As impressive as such simulations are, they are still far short of macroscopic scales: a solid cube 1 micron on a side contains over a thousand times more atoms. Within the past decade, priority has been given to developing truly multiscale methods for modeling materials properties, with seamless integration of atomic scale, intermediate length scale, and continuum methods.
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Lastly, the push to integrate simulations into new materials design should intensify, with work continuing in parallel both on realiza tions for particular systems and on the development of broadly applicable tools based on knowledge gained from these collaborations. Centers and Facilities in CMMP Research Both the complexity of scientific challenges and the resources required to con duct a successful CMMP research program have increased in recent years.
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Current multi investigator research centers, such as Materials Research Science and Engineering Centers, which replaced the MRLs in the mid-1990s, and the Science and Technol ogy Centers, are highly utilized by CMMP researchers. These centers are focused on collaborative, interdisciplinary projects as well as on education and public outreach.
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now invests a significant portion of its resources toward funding large-scale facilities: the synchrotron facilities at Cornell University and at the University of Wisconsin-Madison, a beam line at the neutron-scattering facility at the National Institute of Standards and Technology, and the National High Magnetic Field Laboratory at Florida State University. NSF DMR should set budget priorities between single PIs and small groups, centers, and facilities.
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The interdisciplinarity of CMMP research is reflected in part by the demo graphics of investigators supported by NSF DMR and by DOE Basic Energy Sci ences. Figure 11.5 shows the demographics of materials researchers supported by NSF DMR; besides physicists, this enterprise involves engineers, chemists, bi ologists, mathematicians, and researchers in other disciplines.
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In turn, the committee consid ers here light sources, neutron sources, electron microscopy, high-magnetic-field facilities, nanocenters and materials synthesis, and high-performance computing facilities. Prioritized recommendations are provided for each class of facility (see the respective "Recommendations" subsections below)
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The importance of light sources will increase over the next decade, and indeed they are indispensable to meeting all of the CMMP grand challenges simply because of the power of images obtained at the length scales ultimately responsible for macroscopic physical phenomena and underpinning the functionality of materials, devices, and organisms. In the coming decade, the committee therefore looks for ward to the continuation, among other things, of diffraction studies to locate atoms in new materials and novel nanostructures with, for example, impact on the energy problem and future information technology; high-resolution photoemission to probe emergent quantum phenomena in transition metal oxides; and time-resolved studies of dynamical processes in biology.
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Light sources are primarily used for hard x-rays for scattering experiments. Spectroscopy is the second more popular use, with most of the use occurring at the National Synchrotron Light Source and the Advanced Light Source (ALS)
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NOTE: NSLS, National Synchrotron Light Source; SSRL, Stanford Synchrotron Radiation Laboratory; ALS, Advanced Light Source; APS, Advanced Photon Source. SOURCE: Department of Energy.
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FIGURE 11.8 The total number and location of third-generation synchrotron beam ports around the world. SOURCE: Department of Energy.
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to medicine, but also for spectroscopy, especially in conjunction with high magnetic fields; • New special-purpose sample environments, ranging from sample stages that incorporate scanning probe microscope drivers to pressure cells and series-connected hybrid magnets. Application areas opened by these sample environments range from the engineering of micro- and nanomechanical systems to Earth and planetary sciences, where high-pressure environments occur naturally but cannot be accessed directly; • Concepts for low-cost ($5 million to $10 million)
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This means that prioritization for these facilities is especially important. Recommendations for Light Sources in CMMP Research Informed by presentations and discussion at the CMMP 2010 Facilities Work shop (see Appendix C)
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214 C o n d e n s e d - M at t e r and M at e r i a l s P h ys i c s FIGURE 11.9 Increased x-ray brilliance, which measures the flux of photons per unit of phase space volume, can be achieved by combinations of increases in raw beam power and improvements in beam coherence. NOTE: VUV, vacuum-ultraviolet.
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. The consortium should formulate a light source technology roadmap and make recommendations on the R&D needed to reach milestones on the roadmap for a new generation of light sources, such as seeded x-ray free-electron lasers, energy-recovery linear-accelerator-driven National Research Council, Free Electron Lasers and Other Advanced Sources of Light: Scientific Research Opportunities, Washington, D.C., National Academy Press, 1994.
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The sponsoring agencies of the consortium should fund the R&D needed to reach the milestones on the roadmap. Recommendation: DOE should exploit fully the existing third-generation synchrotrons; this means utilizing the remaining straight sections at the N ational Synchrotron Light Source, Stanford Positron Electron Accelerating Ring, Advanced Light Source, and Advanced Photon Source, and recapitaliz ing obsolete beam lines at all four facilities.
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Neutron spin echo techniques provided new insights into polymer chain dynamics and transitions. There can be no doubt that neutron sources and related major facilities will make major contributions to all of the grand challenge areas identified in this report.
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11-10 a, b motion of hydrogen atoms will continue to be unmatched for studies of hydrogen storage materials, catalysts, polymers, and biomaterials. Current Status of Neutron Sources The neutron community in the United States is entering an exciting period.
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In addition, the rate of growth of neutron sources in the Asia-Pacific region will likely surpass the capabilities in the United States within the next decade. For example, China is building three new neutron sources, the Japan Proton Ac celerator Research Complex is being completed in Japan, there is a major reactor upgrade in Korea, and a new Australian research reactor has recently started up.
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. This would double the number of beam lines that can be supported, enabling a much broader scientific program and providing the optimal route to a significant number of additional high-flux beam lines (about 25)
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In order for projects that involve the use of neutrons to be carried out, faculty must have their own grants to support graduate students and postdoctoral assistants; • Full staffing of beam lines; the current level of three to four staff scientists per instrument needs to increase to at least five to better utilize the invest ment in the instrumentation; • Continued funding to permit full operating time of facilities in order to accommodate all very highly rated proposals; • Significant investment in ancillary equipment or sample environments, for example, samples in extreme environments of temperature, pressure, and magnetic field; and • Substantial investment in software development, including data analysis, vi sualization, modeling, and so on. The project on Distributed Data Analysis for Neutron Scattering Experiments (DANSE)
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Recommendations for Neutron Sources in CMMP Research Recommendation: DOE should complete the instrument suite for the SNS at Oak Ridge National Laboratory, together with provision of state-of-the-art ancillary equipment for these instruments, in order to gain the maximum benefit from the recent investment in the SNS. Recommendation: DOE should construct the second target station at SNS as the top priority for major capital investment for neutron sources, since it will facilitate a wide range of new science and will provide qualitatively different capabilities for cold neutron studies.
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New techniques include tomography as well as holography for magnetic materials and dopant profiles. Electron microscopy is well positioned to address a wide range of important, upcoming characterization challenges in CMMP.
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The smaller base of users of e lectron-beam sources reflects the fact that electron microscopes are comparatively widespread, and the national facilities offer significant opportunities to the more sophisticated users: atomic resolution imaging at LBNL, in situ studies such as radiation effects at ANL, and microanalysis and spectroscopy at ORNL. Yet the largest usage, perhaps as high as 80 to 90 percent of the aggregate workload, of electron microscopy takes place at smaller, local facilities or in the laboratories of individual PIs, because of the ubiquitous use of electron microscopy for CMMP materials characterization.
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array could break through the 0.1 nanometer resolution barrier. NOTE: OÅM, One-Angstrom Microscope; ORNL, Oak Ridge National Laboratory; STEM, Scanning Transmission Electron Microscope; BNL, Brookhaven National Laboratory; TEM, Transmission Electron Microscope; ARM, Atomic Resolution Microscope.
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The project is part of DOE's 20-year roadmap of Facilities for the Future of Science, and after its completion in 2009, the instrument will be made available to the scientific user community at the National Center for Electron Microscopy. The vision for the TEAM project is the idea of providing a sample space for electron-scattering experiments in a tunable electron optical environment by re moving some of the constraints that have limited electron microscopy until now.
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Recommendations for Electron Microscopy in CMMP Research Recommendation: DOE and NSF should support the CMMP community's needs for electron microscopy instrumentation at universities on a competi tive basis. Cutting-edge electron microscopy technique development (such as the DOE TEAM project)
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Furthermore, CMMP research provides advanced materials, including superconductors with better performance, special conductors, and high-strength alloys. These materials form the critical components for magnets used in applications ranging from atomic particle accelerators to medical magnetic resonance imaging (MRI)
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Depending on the application, the quality and usefulness of a facility are determined also by factors such as the homogeneity of the field, the diameter of the magnet bore, or the availability of an environment amenable to low-noise measurements. Furthermore, for much of CMMP research, another important factor is the simultaneous access to low sample temperatures, that is, a large ratio of magnetic-field strength to temperature.
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This would allow the investigation of the neutron and x-ray scattering properties of materials in high magnetic fields. Currently, there are interesting design proposals to add hybrid magnets of fields of about 30 T to beam lines at the SNS at ORNL, and at the APS at ANL.
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This is a theme that needs to be extended and broadened in the next decade in order for the United States to recapture its leadership in the area of the discovery of new materials. In this subsection, nanocenters are discussed and the model is considered for the design and discovery of new materials of interest to CMMP researchers, such as bulk crystals, novel thin films, and superlattices.
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In addition to the NSF NNIN program, DOE has established Nanoscale Science Research Centers at five national laboratories: the Center for Nanophase Materials Sciences at ORNL, the Molecular Foundry at LBNL, the Center for Integrated Nan otechnologies jointly operated by Sandia National Laboratories and Los Alamos National Laboratory, the Center for Nanoscale Materials at ANL, and the Center for Functional Nanomaterials at Brookhaven National Laboratory. These centers are largely dedicated to materials synthesis, fabrication, and characterization.
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The NIST Center for Nanoscale Science and Technology has separate divisions that emphasize scientific programs and user sup port. The NIST scientific programs focus on solving major measurement-related obstacles in the path from discovery to production.
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Balance must be sought be tween support of the individual investigators and small groups of investigators relative to centers, instrumentation, and major facilities investments. Recommendations for Materials Synthesis and Nanocenters in CMMP Research Nanoscience is a core discipline whose advances will affect all of the other challenges, from emergent phenomena (Chapter 2)
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In understanding how such resources address the needs of CMMP researchers, it is important to note that large-scale computation is an important component of many scientific fields that share these resources. Below, the com mittee describes the major U.S.
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(Right) National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory.
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Support for computational facilities from sources such as the NSF Major Research Instrumentation program should be encouraged, and budgeting for computer equipment in theoretical and computational CMMP FIGURE 11.16 FY 2006 Department of Defense high-performance computing requirements, alloca tions, and utilization breakdown for individual "computational technology areas." Computational Chemistry, Biology, and Materials Science (CCM) is third from the left; other areas are Computational Structural Mechanics (CSM)
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to probe the structure and properties of materials over a wide range of length scales is essential for continued progress in CMMP research. The new-generation facilities (light and neutron sources, magnetic-field facilities, and electron micro scopes)
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