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January 2014

Mastering Materials Far from Equilibrium

EFRCs and the Fifth Grand Challenge

Tyler Josephson & Eyas Mahmoud

A cartoon showing stable, low-energy (blue) and unstable, high-energy (red) states and the approach to a non-equilibrium state (point of arrow) from the equilibrium state (lowest energy).

Non-equilibrium conditions are what allow planes to fly, soda to be carbonated, and steel to remain unrusted, but many natural and artificial processes prefer to be at equilibrium conditions, which is the most stable state of a system. However, the most desirable state is often far from these equilibrium conditions. Recognizing the importance of non-equilibrium processes in energy, the U.S. Department of Energy (DOE) identified the Fifth Grand Challenge for science in the 21st century to be: How do we characterize and control matter awayespecially very far awayfrom equilibrium?

As scientists better understand the properties of non-equilibrium systems, we learn how to control them to produce robust electronics, self-assembly technologies for biologically inspired molecular-machines, radiation-resistant materials, efficient solar energy capture and storage, and much more. Researchers at DOE-sponsored Energy Frontier Research Centers (EFRCs) have been exploring these exotic, non-equilibrium conditions, and in this article, we highlight several diverse examples of recent progress.

Improving the safety of nuclear reactors with advanced materials. Nuclear reactors and their waste create inherently non-equilibrium conditions, and the materials involved must withstand intense temperatures and radiation doses while maintaining their structural integrity and mechanical strength. Several EFRCs have been studying materials under these conditions to improve future nuclear technologies and disaster response. Researchers at the Materials Science of Actinides (MSA) EFRC identified the ways in which nanostructured monazite, a potential storage form for highly radioactive waste, amorphized or lost crystallinity and became weaker when exposed to high-energy ions and recrystallized when exposed to high-energy electrons. Nuclear waste often emits both kinds, and the MSA Center proposes that radiation-tolerant materials could be designed such that different types of radiation offset crystallization and amorphization.

Researchers at the Center for Materials at Irradiation and Mechanical Extremes (CMIME) have found that controlling the spread of defects caused by radiation is key to improving material resistance to radiation. Recently, they synthesized composites of a model system of copper and niobium in alternating nanolayers, so that defects formed by irradiation move to a nearby copper-niobium interface instead of aggregating to form voids, which lead to mechanical weakening. By improving the fundamental understanding of these non-equilibrium processes at interphase boundaries in nanocomposites, new radiation-resistant materials are being developed for long-term waste storage and robust nuclear plant construction.

Engineering molecular environments to achieve novel material properties. Accumulation of static electricity on polymers is a serious technological problem responsible for shocks and explosions, as well as damage to satellites and other electronic equipment totaling billions of dollars each year. At the core of this problem are radicals and static discharge, both of which involve non-equilibrium states. Researchers at the Non-Equilibrium Energy Research Center (NERC) have discovered that adding small amounts of radical-scavenging molecules, including vitamin E, can prevent the accumulation of charge in these polymers, reducing the failure of electronic circuitry.

Researchers at NERC have also found a way to alter the chemical properties of organic molecules at non-equilibrium conditions by engineering their surrounding molecular environment, thus manipulating their equilibrium properties. By tethering organic molecules onto the surface of non-spherical nanoparticles, they showed that regions of high curvature on a surface are preferentially charged in an acidic solution. Understanding this relationship between curvature and local electrostatics allows for fine control of nanoscale self-assembly that can be used to direct the shapes of adsorbing biomolecules for applications in pharmaceuticals, energy, and electronics.

Non-equilibrium principles applied to solar cells and hydrogen. Flames create highly non-equilibrium conditions with extreme temperature gradients, short-lived chemical intermediates, and complex fluid dynamics. The Combustion Energy Frontier Research Center (CEFRC) studies the physics, chemistry, and materials science of nanoparticles produced inside flames. They recently demonstrated a new technique that combines nanoparticle synthesis with thin-film formation for dye-sensitized solar cells. By injecting small amounts of a titanium material into the fuel mixture of a flame, TiO2 nanoparticles are produced inside the extreme conditions of the flame, and they impinge on a rotating disk to form a thin film in a single-step procedure. Through this technique, properties of solar cells can be controlled by varying different experimental parameters such as flame geometry, composition, temperature, nanoparticle size, and the presence and concentration of metal dopants.

Moving to more extreme conditions, researchers at the Energy Frontier Research Center in Extreme Environments (EFree) studied the properties of solid hydrogen at 300 gigapascals of pressure, which is nearly the pressure at the earth's core and is more than 1 million times atmospheric pressure. Using theoretical calculations and recent experimental results, they found that hydrogen, a gas under everyday conditions, forms a stacked honeycomb-like structure resembling graphene layers. They showed how hydrogen metallizes, forming first a directionally dependent, transparent metal, quite different from alkali metals, to which it was formerly assumed to be similar. If graphene-structured hydrogen layers could be stabilized at ambient conditions, they would possibly have exotic properties, such as high-temperature superconductivity.

Outlook. Non-equilibrium systems are more than carbonated soda and rust-proof steel, but nuclear energy, solar cells, and states of materials never before observed. The examples above are just a few examples of how DOE-funded research on non-equilibrium conditions has led to fruitful results for radiation-resistant materials for nuclear fuel storage, static-resistant polymers that can save billions of dollars a year because of electric equipment damage, and efficient solar cells from flame-directed nanoparticle synthesis. Even more amazing discoveries lie ahead as scientists continue to investigate these exotic conditions.

More Information

Lu F, Y Shen, X Sun, Z Dong, RC Ewing, and J Lian. 2013. "Size Dependence of Radiation-induced Amorphization and Recrystallization of Synthetic Nanostructured CePO4 Monazite." Acta Materialia 61:2984-2992. DOI: 10.1016/j.actamat.2013.01.058

Han W, MJ Demkowicz, NA Mara, E Fu, S Sinha, AD Rollett, Y Wang, JS Carpenter, IJ Beyerlein, and A Misra. 2013. "Design of Radiation Tolerant Materials via Interface Engineering." Advanced Materials 25(48):6975-6979. DOI: 10.1002/adma.201303400

Nikraz S and H Wang. 2013. "Dye Sensitized Solar Cells Prepared by Flames Stabilized on a Rotating Surface." Proceedings of the Combustion Institute 34(2):2171-2178. DOI: 10.1016/j.proci.2012.06.069

Walker DA, EK Leitsch, RJ Nap, I Szleifer, and V Grzybowski. 2013. "Geometric Curvature Controls the Chemical Patchiness and Self-assembly of Nanoparticles." Nature Nanotechnology 8:676-681. DOI: 10.1038/nnano.2013.158

Baytekin HT, B Baytekin, TM Hermans, B Kowalczyk, and BA Grzybowsk. "Control of Surface Charges by Radicals as a Principle of Antistatic Polymers Protecting Electronic Circuitry." Science 341(6152):1368-1371. DOI: 10.1126/science.1241326

Cohen RE, II Naumov, and RJ Hemley. 2013. "Electronic Excitations and Metallization of Dense Solid Hydrogen." Proceedings of the National Academy of Sciences of the United States of America 110(34): 13757-13762. DOI: 10.1073/pnas.1312256110

Acknowledgments

Lu et al.: This work was supported as part of the Materials Science of Actinides, an Energy Frontier Research Center funded by the DOE, Office of Science, Office of Basic Energy Sciences.

Han et al.: This work was supported by the Center for Materials in Irradiation and Mechanical Extremes, an Energy Frontier Research Center funded by DOE, Office of Science, Office of Basic Energy Sciences.

Nikraz and Wang: This work was supported by the Combustion Energy Frontier Research Center, an Energy Frontier Research Center funded by DOE, Office of Science, Basic Energy Sciences.

Walker et al.: This work was supported by the Non-equilibrium Energy Research Center, an Energy Frontier Research Center funded by DOE, Office of Science, Office of Basic Energy Sciences. DAW acknowledges support provided by the National Science Foundation MRSEC program at Northwestern University and the Ryan Fellowship program.

Baytekin et al.: This work was supported by the Non-Equilibrium Energy Research Center, an Energy Frontier Research Center funded by DOE, Office of Science, Office of Basic Energy Sciences. TMH acknowledges a grant from the Human Frontier Science Program.

Cohen et al.: This work was supported by the EFree, an Energy Frontier Research Center funded by DOE, Office of Science, Basic Energy Sciences (RE Cohen and II Naumov), and the U.S. National Science Foundation and DOE/National Nuclear Security Administration (RJ Hemley).

About the author(s):

  • Tyler Josephson is a Ph.D. candidate at the University of Delaware and is a student in the Catalysis Center for Energy Innovation. He is advised by Dion Vlachos. He is using computational tools to fundamentally understand solvent effects in reactions used to produce fuels and chemicals from biomass. Tyler holds a B.S. in Chemical Engineering from the University of Minnesota.

  • Eyas Mahmoud is a Ph.D. candidate at the University of Delaware and is a student in the Catalysis Center for Energy Innovation. He is advised by Raul Lobo. Eyas is working on developing renewable routes to chemicals such as plasticizers and polyesters. One specific area of interest is the renewable chemical manufacture for the production of p-xylene, a feedstock for polyester and polyethylene terephthalate plastics. Eyas holds a B.S.E. in Chemical and Biomolecular Engineering from the University of Pennsylvania.

More Information

Lu F, Y Shen, X Sun, Z Dong, RC Ewing, and J Lian. 2013. "Size Dependence of Radiation-induced Amorphization and Recrystallization of Synthetic Nanostructured CePO4 Monazite." Acta Materialia 61:2984-2992. DOI: 10.1016/j.actamat.2013.01.058

Han W, MJ Demkowicz, NA Mara, E Fu, S Sinha, AD Rollett, Y Wang, JS Carpenter, IJ Beyerlein, and A Misra. 2013. "Design of Radiation Tolerant Materials via Interface Engineering." Advanced Materials 25(48):6975-6979. DOI: 10.1002/adma.201303400

Nikraz S and H Wang. 2013. "Dye Sensitized Solar Cells Prepared by Flames Stabilized on a Rotating Surface." Proceedings of the Combustion Institute 34(2):2171-2178. DOI: 10.1016/j.proci.2012.06.069

Walker DA, EK Leitsch, RJ Nap, I Szleifer, and V Grzybowski. 2013. "Geometric Curvature Controls the Chemical Patchiness and Self-assembly of Nanoparticles." Nature Nanotechnology 8:676-681. DOI: 10.1038/nnano.2013.158

Baytekin HT, B Baytekin, TM Hermans, B Kowalczyk, and BA Grzybowsk. "Control of Surface Charges by Radicals as a Principle of Antistatic Polymers Protecting Electronic Circuitry." Science 341(6152):1368-1371. DOI: 10.1126/science.1241326

Cohen RE, II Naumov, and RJ Hemley. 2013. "Electronic Excitations and Metallization of Dense Solid Hydrogen." Proceedings of the National Academy of Sciences of the United States of America 110(34): 13757-13762. DOI: 10.1073/pnas.1312256110

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.