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Summary Modern materials science builds on knowledge from physics, chemistry, biology, mathematics, computer and data science, and engineering sciences to enable us to understand, control, and expand the material world. Although it is anchored in inquiry-based fundamental science, materials research (MR) is strongly focused on discovering and producing reliable and economically viable materials, from super alloys to polymer composites, that are used in a vast array of products essential to todayâs societies and economies. This report is the result of an in-depth consensus study requested and sup- ported by the National Science Foundation (NSF) and the Department of Energy (DOE), aimed at documenting the status and promising future directions of materi- als research in the United States in the context of similar efforts worldwide. This is the second major survey of the broad area of MR; the first was published in 1990 (Materials Science and Engineering for the 1990s: Maintaining Competitiveness in the Age of Materials, National Academies Press, Washington, D.C.). In 2010, a focused study (Condensed-Matter and Materials Physics: The Science of the World Around Us, National Academies Press, Washington, D.C.) was published. The current re- port reviews the progress and achievements in materials research and changes in the materials research landscape over the past decade; research opportunities for investment for the period 2020-2030; impacts that materials research has had and is expected to have on emerging technologies, national needs, and science; and challenges the enterprise may face over the next decade. 1
2 F r o n t i e r s o f M at e r i a l s R e s e a r c h A remarkable number of paradigm-changing advances have been made in materials research over the past decade, and the pace of discovery is accelerating. Moreover, the tools that support that researchâincluding capabilities for materi- als characterization, synthesis and processing, and computational modelingâhave advanced considerably, enabling previously unachievable insights. The science and engineering are exciting, the prospects for creating and controlling new materi- als are high, and the pathway to important applications is very encouraging. This positive view is tempered somewhat by the prospect that many of the advances that can now be foreseen require resources that are by no means guaranteed, and by the reality that international competition, particularly from China and from Asia more generally, is threatening U.S. leadership in materials research. Certain areas of materials research emerge from this survey as particularly important. Computational materials science and engineering is just one such area. Integrating computational methods (including data science, machine learning, and informatics) with materials characterization and synthesis and processing methods is accelerating the discovery of designer materials and their use in products. This momentum extends into digital manufacturing, wherein additive manufacturing and other processes connect materials synthesis directly with fabrication. Materials for quantum information science (QIS) have emerged as another very high prior- ity direction for the next decade. QIS comprises not only quantum computing but also storage, quantum sensing, and communication technologies, and draws on advances in superconductors, semiconductors, magnets, and two-dimensional (2D) and topological materials. Materials science and technology from across the entire spectrum of materials has enormous potential for impacting the quality and sustainability of Earthâs envi- ronment. One such area that has seen recent progress is in designing new materials to catalyze a range of important chemical reactions. For example, researchers have learned a lot about the role of surface conditions on efficient catalysis, such as in plasma-assisted hot electron catalysis. Future research could certainly improve sustainable manufacturing of materialsâfor example, choice of raw materials, energy-efficient manufacturing methods, and recyclability. This opportunity calls especially for cooperation between universities, national laboratories, and industry, a need that appears multiple times in this report. Continued investment in research infrastructure at all levels is essential for the health of the U.S. materials science enterprise. This includes assets ranging from instrumentation at university laboratories to the largest facilities in our national laboratories. This infrastructure constitutes a treasure for U.S. materials research, and it must be sustained at world leadership levels for the health and productivity of the field.
Summary 3 ILLUSTRATIVE ADVANCES FROM THE PAST DECADE The past decade has seen extraordinary advances in materials research, and these advances cut across the full range of materials classes. For example, grapheneâwhich received only modest attention in the last decadal survey of the disciplineâhas since spawned an exciting field of other 2D materials. Perhaps more importantly, graphene inspired work on new physical phenomena, with potential utility in many electronics applications such as solar cells, transistors, camera sensors, digital screens, and semiconductors. Another surprise of the past decade has been the evolution of additive manufacturing (AM), which while available for decades, has now emerged as an important process that can be used for both mass production as well as for one-off fabrication on demand. A few other major materials advances from the past decade include affordable light-emitting diode (LED) lighting, flat panel displays, and improved batteries. Some important developments were the product of pure discovery-driven science (e.g., topological insulators), while others arose through concerted techno- logical efforts (e.g., Gorilla Glass), and still others represent some combination of the two (e.g., AM and vitrimers). Two major government initiativesâthe Materials G Â enome Initiative (MGI) and the National Nanotechnology Initiative (NNI)â played important roles in stimulating materials research in the United States. Exciting advances were achieved over the past decade in metals, bulk metal- lic glasses, high-performance alloys, ceramics and glasses, among other classes. Composite and hybrid materials have found high-value applications owing to their abilities to withstand harsh environments; as bulk, composite, and coating materi- als; and for their functionality in devices. Advances in coating technologies have led to increased reliability and their use in thermal and environmental protection systems. Layered material systems are replacing advanced monolithic materials in a growing number of applications where the unique properties and functionality of each layer provides dramatically increased performance and life. Great advances have been seen in polymers and in biomaterials of many kinds, and in soft matter such as colloids and liquid crystals. Superconductivity has remained a fertile field, while the area of quantum ma- terials more generallyâincluding materials such as quantum-spin liquids, strongly correlated thin films and heterostructures, novel magnets, graphene and other very thin materials, and topological materialsâis advancing rapidly. ILLUSTRATIVE RESEARCH OPPORTUNITIES Building on these recent advances, the study also found many examples of compelling materials research opportunities anticipated to arise in the coming
4 F r o n t i e r s o f M at e r i a l s R e s e a r c h decade. These exciting opportunities span the full range of materials classes and hold the promise of many valuable applications. Our fundamental understanding of metals and alloys will continue to advance through increasingly coupled experimental and computational modeling, with real- time characterization of materials as their conditions and behavior change. New directions will also come from innovations in the design, composition, processing, and fabrication methods that take advantage of advanced capabilities in materials manufacturing. High-entropy alloys (which have five or more elements present at comparable concentrations) will continue to offer considerable promise in the next decade. Such materials offer the possibility of overcoming dilemmas and barriers associated with traditional alloys, such as strength-ductility trade-offs. A second nontraditional area of metals that seems poised for advances is that of nanostruc- tured metallic alloys, whose morphology and intricate structure is controlled at the nanoscale (e.g., nanotwinned metals). Much of the research in semiconductors and other electronic materials will continue to be driven by the information and computation technology industries, moving toward increasingly complex monolithic integration devices, more highly functional microprocessors, and chips that take full advantage of three-dimensional (3D) layouts. Included will be materials for new devices that combine the functions of memory and logic, and other devices with energy-efficient architectures capable of executing machine learning and other algorithms that significantly differ from traditional computer logic and architectures. Research that will enable more effi- cient power management, at many scales of power and voltage, will also continue to be a major focus. Two-dimensional materials, including graphene, offer opportunities for explor- ing the nature of surface electronic states. By layering such materials, the weak interplay between layers and the presence of designed defects presents a rich area for discovery, with potential opportunities for electronic and optical applications. Topological materials, whose properties are determined by topological properties of their excitation spectra, will continue to offer a wide range of areas for explora- tion, with the potential for a host of applications. Some of the opportunity areas identified for ceramics are energy-efficient pro- cesses for their creation, which will enable the production of denser and ultra-high- temperature ceramics. Increased capabilities for characterization and processing are opening new opportunities in glass research, leading perhaps to their service as solid electrolytes for energy storage and for nonlinear optical devices. Composite materials will become increasingly tailored for more advanced ap- plications, extending well beyond the structural roles they traditionally have per- formed. Areas of promise include incorporating biomaterials as constituents and developing materials with properties that can change in a desirable and predictable
Summary 5 manner over time. In the area of hybrid materials, perovskites will continue to draw significant interest, largely because of their potential advantages for single- junction solar cells. Hybrid nanocomposites, because of their constituent particlesâ good optical and high carrier-mobility properties, offer promise for applications in optoelectronics and photovoltaic conversion technologies. Architected and metamaterials are of interest principally because of their de- signed structures, typically at the micro- or nanoscale levels, which offer a wide range of enhanced functionality to the devices in which they are incorporated. Lightweighting, through the designed distribution of a materialâs composite cells, offers opportunities for a host of technologies in aerospace, transportation, and energy generation, among others. Multifunctional materials, such as those that provide both structure and also thermal management, enhanced communication, or sensing capabilities, are an increasingly important segment of this materials class. Metamaterials are another important class, whose structure provides specific functional responses, and they offer tremendous opportunities in many different technologies such as energy-efficient light sources, sensing applications, thermal engineering, and microwave technology. This discussion of promising research op- portunities is only illustrative. The full report provides further detail about these directions, plus additional ones. While there is considerable, justifiable motivation and excitement for new research in polymers, biomaterials and other forms of soft matter, as well as, elec- tronic, photonic, and hybrid materials, it needs to be clear that more traditional areas of materials research offer important opportunities, too. It should be noted here that Key Findings and Recommendations are meant to designate a higher level of generality, but by no means a higher level of importance, than Findings and Recommendations. Key Finding: Research into metals, alloys, and ceramics continues to provide fundamental understanding of atomic-scale processes that govern synthesis- microstructure-property relations in many classes of materials. Armed with this understanding and state-of-the-art synthesis, characterization, and com- putational tools, scientists can realize novel alloys and micro/nanostructures with extraordinary properties. Traditional areas of materials research can have surprising new developments, for example, in multicomponent, high-entropy alloys and inorganic glasses. Key Recommendation: Federal funding agencies (National Science FoundaÂ tion, Department of Energy, Department of Defense) should maintain robust Â programs to support, and in some cases expand, fundamental Â esearch in r long-established areas such as metals, alloys, and ceramics.
6 F r o n t i e r s o f M at e r i a l s R e s e a r c h Key Finding: Quantum materials science and engineering, which can in- clude superconductors, semiconductors, magnets, and two-dimensional and topological materials, represents a vibrant area of fundamental research. New understanding and advances in materials science hold the promise of enabling transformational future applications, in computing, data storage, communi- cations, sensing, and other emerging areas of technology. This includes new computing directions outside Mooreâs law, such as quantum computing and neuromorphic computing, critical for low-energy alternatives to traditional processors. Two of NSFâs â10 big ideasâ specifically identify support of quantum materials (see The Quantum Leap: Leading the Next Quantum Revolution and Midscale Research Infrastructure). Key Recommendation: Significant investments by, and partnerships among, the National Science Foundation, Department of Energy (DOE), National Institute of Standards and Technology, Department of Defense (DoD), and Intelligence Advanced Research Projects Activity will accelerate progress in quantum materials science and engineering, so crucial to our future economy and homeland security. U.S. agencies with a stake in advanced computing, under the possible leadership of DOEâs Office of Science and National Nuclear Security Administration laboratories and DoD research laboratories (Army Research Laboratory, Naval Research Laboratory, and Air Force Research Laboratory), should undertake to support new initiaÂ tives to study the basic materials science of new computing paradigms durÂ ing the next decade. To remain internationally competitive, the U.S. materiÂ als research community must continue to grow and expand in these areas. DEMAND FROM THE ULTIMATE APPLICATIONS Fundamental connections exist between the broad field of materials research and the needs and interests of the industrial sector. Looking just at national secu- rity as an example, materials research has led to new materials that provide better armor that weighs less, to batteries that deliver more power to the warfighter in the field, and to materials better able to withstand extreme conditions, such as ultra-high-temperature materials for hypersonic flight and propulsion systems operating above 2000Â°C. In energy-related industries there is growing demand for high-performance materials that are able to perform under a variety of extreme operating environ- ments. Two examples of demanding applications are lightweight, high-strength, high-toughness materials for aerospace and terrestrial transportation applications and structural materials and fuel systems for advanced fission or fusion energy systems capable of extraordinary resistance to high radiation doses. More generally,
Summary 7 energy challenges span production, distribution, transduction, and utilization. Materials such as improved photovoltaics and advanced batteries contribute fun- damentally. Energy utilization can be improved through materials development such as better catalytic materials. Another wide-ranging demand is for materials needed to move, store, pump, and manage heat. Greater than 90 percent of the energy used by humans for elec- tricity, for heating and cooling applications, and for transportation originates from thermal processes. Consequently, even small efficiency improvements in the abil- ity to control and convert thermal energy has a significant impact on the worldâs energy use. Throughout the materials research community there is a broadly voiced desire for greater interactions among universities, private enterprise, and national labo- ratories. Efforts to streamline cooperation and flow of information among these major engines of creativity and innovation in materials science and technology will pay dividends. The continuous and desirable interplay of basic science stimulat- ing practical advances and technological challenges stimulating new fundamental research should be reinforced at every opportunity. The United States needs to ensure that it is translating basic discoveries into practical technologies. These considerations lead to a recommendation for a new sort of funding mechanism designed to stimulate faculty, students, industrial scientists, and engineers to engage in intimate teamwork. Key Finding: Many of the real-world challenges and opportunities in materi- als research occur at the intersections among traditional disciplines, and at the interfaces between fundamental and applied research. Pure science is stimu- lated by proximity to applied research. Collaboration and information transfer among different disciplines and among academia, industry, and government laboratories greatly increase the likelihood of successfully meeting these chal- lenges and capitalizing on these opportunities. Key Recommendation: Government agencies, led by the Office of Science and Technology Policy, should work with high priority to foster commuÂ nication among materials research stakeholders through the support of interdisciplinary research and the development of modalities for freer flowÂ ing interactions among universities, private enterprise (including start-up ventures), and national laboratories. Key Recommendation: The White House Office of Science and Technology Policy should provide leadership in the development of awards that enable diverse funding agencies to work together when needed to facilitate colÂ laboration among university and industry researchers.
8 F r o n t i e r s o f M at e r i a l s R e s e a r c h Key Recommendation: The National Science Foundation (NSF) should deÂ velop a new type of center that will enable, and indeed stimulate, students, faculty, and industrial scientists and engineers to work side by side. Such a Discovery to Translation Materials Research Center would create a unique learning and research environment. The effort should be supported by several NSF directorates and should continue for a minimum of a decade. The concept of a Discovery to Translation Materials Research Center would complement NSFâs existing Materials Research Science and Engineering Centers, which promote fundamental research, and its Engineering Research Centers, which promote technology development, by bringing both into functional synergy in an unprecedented manner. The desire to connect basic materials research more cooperaÂively with technology should in no way be taken as lack of support for t high-risk, fundamental research, which continues to be of critical importance. Key Finding: Materials science and technology has an enormous impact on the quality and sustainability of Earthâs environment across the entire spectrum of materials types. This is another important opportunity for university, national laboratory, and industry cooperation. Key Recommendation: Research in numerous directions that improve susÂ tainable manufacturing of materials, including choices of feedstocks, energy efficiency, recyclability, and more, is urgently needed. Creative approaches for funding materials research toward sustainability goals should be deÂ veloped by the National Science Foundation, Department of Energy, and other agencies. INFRASTRUCTURE NEEDS Many of the advances in materials research over the past decade are a conse- quence of continued investments and improvements in the tools used to conduct this research. However, to unlock the promise of the many emerging opportunities, the study identified a number of structural steps that are necessary to facilitate the greatest effectiveness of materials research in the United States. The past decade has seen significant advances in the characterization, synthesis and processing, and computational capabilities available to materials researchers, enabling previously unachievable materials insights. Characterization has been advanced especially through tools such as transmission electron microscopy, atom probe tomography (APT), scanning probe microscopy, ultrafast probes, and 3D- and 4D-characterization capabilities (where 3D is our common three-dimensional space with length, width, and depth, and 4D adds the dimension of time). Precision
Summary 9 synthesis promises to transform materials science in a revolutionary way. A number of methods and tools are enabling new capabilities in precision synthesis. The state of the art now allows researchers to control, with fidelity and exactness, the place- ment and arrangement of atoms, molecules, and defectsâwith the latter being of importance because they often control material properties. In the area of computational capabilities, researchers have seen significant im- provements in modeling materials on multiple length scales, enabling (for example) the calculation of material properties with high fidelity. These computationally derived results are being used to predict structure-property relationships for many material types, discover new structures, and enhance the interpretation of experi- mental data. In addition to physics-based models, data-driven machine learning has been used to explore materials compositional space, identify new structures, discover quantum phases, and identify phases and phase transitions. Another major enabling advance has been through the confluence of com- putational design of material properties, fabrication processes with nanometer to micrometer control, and experimental characterization methods with equally fine resolution. The integration of these capabilities has made it possible to create novel bulk materials with radically superior properties via architectural control at the ap- propriate scales. In much the same way that arches, columns, beams, and buttresses revolutionized the construction of buildings, towers, and bridges in past centuries, the materials community is now exploiting material architecture to expand the material design space in multiple dimensions, independently manipulate material properties that are currently coupled, and develop materials with vastly superior properties than can be achieved with solid objects. The large amounts of data generated at some of the major U.S. materials facilities has led to a strong interest in coupling these experiments with modeling and simulation capabilities. Several agencies have developed advanced computational facilities that play major roles in predictive modeling of functional materials and also in coherently understanding materials across many length scales. Capabilities for assessing and characterizing materials, processing and syn- thesizing those materials, and modeling and simulating their properties are at the heart of materials research. The network of instruments and facilities that provide researchers the ability to carry out these investigationsâfrom the individual investiÂ ator, through midscale instrumentation facilities and science research g centers, to national facilitiesâis the infrastructure that supports the entire mate- rials research enterprise. Enormous demand on research infrastructure exists in all subfields of materials research, and over the past 10 years the ever-rising costs of acquiring and main- taining state-of-the-art research infrastructure, combined with a lack of adequate funding avenues for instrumentation, have culminated in a critical situation for all of materials science and engineering in the United States.
10 F r o n t i e r s o f M at e r i a l s R e s e a r c h For the most part, the federal agencies, private foundations, and industry that fund most university research do not provide funding for the instrumenta- tion that is needed to carry out that work. NSF is the major exception, sponsor- ing research instrumentation through its Major Research Instrumentation (MRI) program. But that program is not large enough to address the current needs across materials research and engineering. DoDâs Defense University Research I Â nstrumentation Program (DURIP) can help in principle, but the level of its typi- cal grant is too low for a large portion of the instruments used in materials science and engineerÂng. DOE operates impressive scattering facilities that are integral to i several fields of materials research, just as the National Institute of Standards and Technology (NIST) Center for Neutron Research and the National Aeronautics and Space Administrationâs (NASAâs) portion of the International Space Station (ISS) support some key materials research. However, those sorts of national facili- ties, while essential for our continued progress in materials research, cannot satisfy the need for research infrastructure at universities, where much of the nationâs forefront research in materials is carried out. In many cases, it is critical to have instrumentation on campusâfor example, a research project that involves synthesis of new materials typically requires a constant and immediate feedback loop be- tween synthesis, structure, and property measurements that may go through many cycles within a short period of time. It is not feasible to carry out this research by relying on remote facilities. This is true for most materials research. As a result of the lack of funding options, the burden to support research in- strumentation has been shifted largely to the universities. The typical result is that universities support new research instrumentation as part of a package to attract young experimentalists. But the consequence of that model is a lack of funding to sustain and upgrade the instrumentation over time. The model also leads to downward pressure on hiring of young people. Key Finding: Infrastructure at all levels, from midscale instrumentation for materials characterization, synthesis, and processing with purchase costs of $4 million to $100 million in universities and national laboratories to large-scale research centers like synchrotron light sources, free electron lasers, neutron scattering sources, high field magnets, and superconductors is essential for the health of the U.S. materials science enterprise. Midscale infrastructure, in par- ticular, has been sorely neglected in recent years, and the cost of maintenance and dedicated technical staff has increased enormously. Key Recommendation: All U.S. government agencies with interests in maÂ terials research should implement a national strategy to ensure that univerÂ sity research groups and national laboratories have local access to develop, and continuing support for use of, state-of-the-art midscale instruments
Summary 11 and laboratory infrastructure essential for the advancement of materials research. This infrastructure includes materials growth and synthesis faciliÂ ties, helium liquefiers and recovery systems, cryogen-free cooling systems, and advanced measurement instruments. The agencies should also continue support of large facilities such as those at Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, Argonne National Laboratory, SLAC National Accelerator Laboratory, National Synchrotron Light Source II (Brookhaven National Laboratory), and National Institute of Standards and Technologyâand engage and invest in long-range planning for upÂ grades and replacements for existing facilities. Key Finding: Progress in 3D characterization, computational materials sci- ence, and advanced manufacturing and processing have enabled an increas- ing digitization across disciplines of materials research and has in some cases dramatically accelerated and compressed the time from discovery to inclusion in new products. Key Recommendation: Federal agencies (including the National Science Foundation and Department of Energy) with missions aligned with the advancement of additive manufacturing and other modes of digitally conÂ trolled manufacturing should by 2020 expand investments in materials reÂ search for automated materials manufacturing. The increased investments should be across the multiple disciplines that support automated materials synthesis and manufacturing. These range from the most fundamental reÂ search to product realization, including experimental and modeling capaÂ bilities enabled by advances in computing, to achieve the aim that by 2030 the United States is the leader in the field. Key Finding: The Materials Genome Initiative, and the earlier Integrated Computational Materials Engineering approach, recognized the potential of integrating and coordinating computational methods, informatics, materials characterization, and synthesis and processing methods to accelerate the dis- covery and deployment of designer materials in products. The translation of these methodologies to specific industries has resulted in numerous success- ful applications that have reduced the development time with corresponding cost savings. Key Recommendation: The U.S. government, with National Science FounÂ dation, Department of Defense, and Department of Energy coordinating, should support the quest to develop new computational and advanced data- analytic methods, invent new experimental tools to probe the properties
12 F r o n t i e r s o f M at e r i a l s R e s e a r c h of materials, and design novel synthesis and processing methods. The efÂ fort should be accelerated from todayâs levels through judicious agency investments and continue over the next decade in order to sustain U.S. competitiveness. NATIONAL COMPETITIVENESS OF U.S. MATERIALS RESEARCH The importance of materials research to a countryâs economic well-being and security is now a given, and countries the world over pursue national programs to support materials research and to facilitate the transition of that research to the marketplace. As part of this study of progress in materials research, an examina- tion was made of the contribution of materials research to the world economy and materials programs and investment in a select number of countries. One salient result of that examination is that many countriesâ programs are more focused and more directly tied to economic development than the program of the United States. Asian countries, most notably China and South Korea, now invest a greater fraction of their gross domestic product (GDP) in materials research than do the United States and European countries. Key Finding: Intense competition among developed and developing nations for leadership in the modern economic drivers, including smart manufacturing and materials science, will grow over the coming decade. Key Recommendation: The U.S. government, with input from all agencies supporting materials research, should take coordinated steps beginning in 2020 to fully assess the threat of increased worldwide competition to its leadership in materials science and in advanced and smart manufacturing. The assessment program, which should be established on a permanent basis, should also define a strategy by 2022 to combat this threat. Materials research is a critical underpinning to economic growth as well as national competitiveness, wealth and trade, health and well-being, and national defense. The impact that materials research has had on emerging technologies, na- tional needs, and science has been important to date, and it is expected to become even more so as the United States moves through the digital and information age and faces current and future global challenges. Many of the worldâs larger nations and economies have recognized this relationship, and recent trends show that today many nations have developed and articulated national investment strategies to en- sure robust progress in materials research for national competitiveness in a global
Summary 13 economy. The impact that materials research has had on emerging technologies, national needs, and science has been important to date, and as the United States moves through the digital and information age and faces current and future global challenges, this impact is expected to become even more important.