HIGHLIGHTS

The Stewardship Science Academic Programs (SSAP) Symposium for 2026 took place 0n February 23-24 at the Bethesda North Marriott Hotel and Conference Center in Bethesda, MD.  Each year, this event provides an opportunity for SSAP Center directors and grant holders to present updates in their programs and for students to showcase their work in the poster session, the Symposium’s signature event.

The keynote addresses for this year’s Symposium were presented by Dr. David LaGraffe, Colonel USA (retired), who is the Principal Assistant Deputy Administrator for the NNSA Office of Research, Development, Test, and Evaluation, and Dr. Sarah Nelson, the Assistant Deputy Administrator for the NNSA Office of Experimental Sciences.  Both keynote speakers focused on the role that NNSA plays in providing for the nation’s nuclear deterrent, as well as the ongoing opportunities for meaningful work in fundamental science in support of the NNSA mission.

CDAC Director Russell Hemley provided an update on the Center’s progress over the past two years, and emphasized the numerous ways in which CDAC has evolved since 2003, when the Center was first founded, particularly in the increasing synergy of experiment and theory.  Dr. Hemley also discussed new initiatives in the Center that will address the goals of the Genesis Mission.

CDAC graduate students presented 11 posters at this year’s Symposium, and addressed scientific work from all three Scientific Thrusts.

Audrey Berlin (Utah)
Mineral Physics Insight Into Deformation of Iron Across Temperature, Pressure, and Strain-Rate Space

Devi Dutta Biswajeet (UIC)
CVDiamond :  Artificial Intelligence Agent for Diamond CVD Synthesis

Grady Clopton (UIUC)
Multiscale Modeling of Swift Heavy Ion Track Formation in Redox Active Materials

Farid Fattahpour (UIC) 
First-Principles Modeling of Lattice Anharmonicity in High-Temperature Diffusion

Sumner Gubisch (George Washington) 
Material Selection of Thermoelectric Materials for Laser Powder Bed Fusion

Clayton Halbert (UIC)
High Pressure Structure of Bi_0.5Sb_1.5Te₃ at Ambient and Superconducting Temperatures

Masashi Kimura (Buffalo) 
Effects of Anharmonicity on Superconducting Y-Ca-H Systems

Angela Pak (UIUC)
First-Principles Characterization of the Native Defect Landscape Across Half-Heusler Chemistries

Benjamin Singsun (UIC) 
High P-T Reactions of KBH₄ + H₂ :  Search for Novel High-Density Borohydrides

Max Zipperer (Carnegie Mellon)
Investigating Damage Initiation in Shock Loaded Titanium via Novel High-Energy Diffraction Microscopy Developments

Charlie Zoller (UIC)
Optical Properties of Aluminum at High Pressures and Temperatures

The complete agenda, along with copies of presentation slides for all presentations, is available on the symposium website.

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With its significantly increased flux, the recent upgrade at the Advanced Photon Source (APS-U) has improved the quality of data available from a wide range of x-ray diffraction and spectroscopy experiments, and has also enabled new classes of experiments.  Among the techniques that have benefited the most from APS-U have been imaging experiments, which rely on a tightly focused beam for sub-micron resolution.  This is particularly important for samples at high pressure in the diamond anvil cell, which experience non-hydrostatic stress that can ultimately affect the structure and properties of materials.

A recent collaborative effort between LLNL, HPCAT, GSECARS (APS Sector 13), and the CDAC group at UIC has utilized newly-enabled scanning x-ray diffraction microscopy (SXDM) and x-ray diffraction imaging (XDI) methods combined with 4-probe resistivity measurements to study the superconducting hydride (La,Y)H₁₀. An open question in understanding the near-room temperature superconducting behavior observed in the rare earth hydrides is the extent to which sample heterogeneity affects the observed superconducting transition temperature.  These imaging techniques are the ideal tool for resolving such local effects, which typically are not observed by bulk techniques such as x-ray diffraction.

Imaging results (see Figure) show clear coexistence of cubic and hexagonal phases of (La,Y)H₁₀ between 136 and 168 GPa, spatially resolved at the micron scale, and illustrate structural inhomogeneity in the sample.  Resistivity measurements show that the superconducting transitions occur at 244 K for the cubic phase and near 220 K for the hexagonal phase and illustrate a direct correspondence between structural domains and superconducting behavior.  [Marathamkottil, A. H. M., et al., X-ray diffraction and electrical transport imaging of superconducting hydride (La,Y)H₁₀.  Nature Communications 16, 11222 (2025)].

See the UIC Today Press Release

See the story on the UIC Chemistry LinkedIn Page

See the press release from Argonne National Laboratory

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The 24th International Conference on the Science of Compression in Condensed Matter (SCCM 2025), hosted by the American Physical Society Topical Group on Compression of Condensed Matter, was held from June 22-27, 2025 at the Washington Hilton Hotel in Washington, DC. For the first time, the conference addressed all timescales of compression, from static to dynamic to shock. In addition to a complete range of technical sessions, a series of tutorials were presented by experts in the various topical areas covered by the meeting.  SCCM 2025 also included a poster session and an Early Career Student Symposium. The complete program is available here.

CDAC Director Russell Hemley delivered the first presentation of the meeting, New Materials With Extreme Properties and Performance From Compression of Condensed Matter in the Plenary Session, “The Magical World of Static and Dynamic Compression.”  CDAC Partner Dana Dlott also presented a plenary lecture, High Throughput Tabletop Shock Experiments With Applications to Energetic Materials in the session “All About Energetic Materials.”

CDAC was well represented at the meeting across a wide variety of topical areas.  Presentations including authors affilliated with CDAC are listed below, with CDAC presenters in bold, and CDAC coauthors in parentheses:

A01-1  Russell Hemley :  New Materials With Extreme Properties and Performance From Compression of Condensed Matter

G01-1  Dana Dlott :  High Throughput Tabletop Shock Experiments With Applications to Energetic Materials 

L02-1  Zhuanling Bai :  High Pressure Effects on an Octa-Hydrated Curium Complex : An Experimental and Theoretical Investigation 
(M. Reddington, E. Zurek)

H08-2  Hannah Bausch  :   Thermoelasticity of MgO up to 400 GPa Using Shock-Ramp Compression on the Z Machine
(T. Abbott, S. Jacobsen)

L08-2  Peter Celliers  :  Entropy Differences Between H₂ and D₂ and the Phase Diagram of Hydrogen Isotopes
(R. Hemley)

Z05-3  Alisha Clark  :  Insights Into the Fate of Volatile Species During the Planetary Life Cycle from Dynamic Compression Experiments
(T. Abbott, S. Jacobsen)

H02-4  Dana Dlott :  Hot-Spot Growth in Plastic-Bonded Explosives (PBX) Seen With High Time and Space Resolution

D02-2  Anukriti Ghimire  :  Phase Boundaries, Isotope Effect, and Superconductivity of Lithium Under Pressure
(E. Zurek)

Poster 72 Lindsay Harrison :  Effect of Water on Shockless Ramp Compression of SiO₂ to Upper Mantle Pressure
(S. Jacobsen)

Poster 66  Masashi Kimura  :  Effects of Anharmonicity on Superconducting Y-Ca-H Systems
(E. Zurek)

Poster 23  Ravhi Kumar  :  Enhancement of Seebeck Coefficient and Thermoelectric Efficiency in Mn-Doped SnTe Under Compression

V06-2  Eduardo de Toledo Poldi  :  Compression of Kiatev Quantum Spin Liquid Candidate Na₃Co₂SbO₆ to Megabar Pressures
(Z. Liu, R. Kumar, R. Hemley)

W-06  Danae Polsin  :  The Electride Nature of Ramp-Compressed Sodium in the Terapascal Regime
(E. Zurek)

Jo5-4  Stefano Racioppi  :  Powder X-ray Diffraction Assisted Evolutionary Algorithm for Crystal Structure Prediction
(E. Zurek)

K02-3  Roma Ripani  :  Compression of Hydrazine to Above 200 GPa
(F. Safari, M. Ahart, Z. Liu, S. Gramsch, R. Hemley)

N01-3   Siva Valluri :  Role of Nanostructural Features in Shock-Initiated Reactivity of Milled Composite
(D. Dlott)

V06-1  Kui Wang  :  Superconductivity and Novel Electron Transport of Elemental Superconductors Under Pressure
(R. Hemley)

L03-4  Charles Zoller  :  High Pressure Behavior of the D₂/H₂ – CO₂ System
(M. Ahart, R. Hemley)

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Nanomaterials—materials with two dimensions below 100 nanometers and a thickness of just a few atoms—can exhibit extraordinary properties for technologies like advanced batteries, catalysis, and quantum computing. Most materials today, however, are made from just one or two elements, limiting how adaptable and robust they can be. High-entropy materials, on the other hand, combine five or more different elements together in a homogeneous substance with a defined crystal structure. This chemical diversity, known as configurational entropy, is predicted to make these materials exceptionally stable and resistant to degradation. But making high-entropy materials that remain stable on the nanoscale has been incredibly challenging. In reality, these complex structures often break apart or separate into different phases, especially when trying to make them just a few atoms thick. This has held back their promise in real-world applications.

A paper published recently in the journal Science involving a CDAC collaboration now reports that novel pressure-induced entropic transformations in new high-entropy oxide nanoribbon material lead to resilience even in the harshest environments : temperatures up to 1,000°C, pressures up to 12 GPa, and prolonged exposure to strong acids and bases for up to 7 days.

In this work, a group of researchers from the University of Illinois Chicago, focusing on finding the right chemistry for high entropy oxide stability, has now devised a template-based approach for nanoparticle synthesis using metal sulfide flakes. These flakes acted as a seed for the controlled growth of high-entropy oxide nanoribbons (1D-HEO), preventing phase separation and ensuring all five metal elements remained evenly mixed (Fig. 1, Top).  Through targeted adjustments in the the reaction conditions, the synthesis process resulted in over two orders of magnitude improved control on the width of the nanoribbons—from nanometers to tens of micrometers—while maintaining exceptional uniformity.  This approach not only resulted in a new nanomaterial, but it also allowed an investigation of the formation process and structural evolution in real time. Structural studies using X-ray diffraction to confirm the 1-D structure (Fig. 1, Middle) were carried out at ambient pressure at Northwestern University, while the HPCAT sector at the Advanced Photon Source provided facilities for high pressure diffraction measurements.  Computational simulations of this complicated chemistry provided crucial information on the evolution and transformations of the HEO nanoribbons.

High-pressure experiments reveal an intriguing transformation of the 1D-HEO nanoribbons from orthorhombic to cubic structures at 15 gigapascals followed by the formation of fully amorphous HEOs above 30 gigapascals, which are recoverable to ambient conditions (Fig. 1, Bottom). These transformations introduce additional entropy (structural disorder) into the system at high pressure, in addition to the configurational entropy arising from the number of different transition metals mixing on the one metal site in the structure. This finding offers a way to create low-dimensional, resilient, and high-entropy materials.

The nanoribbons produced by this synthetic route are not only more resilient than conventional materials but also highly promising for practical applications. Unlike traditional high-entropy materials that require expensive high-temperature casting, these nanoribbons can be 3D-printed or spray-coated—a scalable, cost-effective approach for real-world uses, from ultra-robust coatings to next-generation energy storage. This work was a collaborative study, led at University of Illinois Chicago, with a team spanning mechanical engineering, chemistry, physics, and civil and materials engineering, with partners from Stockholm University, the University of Washington, and Argonne National Laboratory.

Shahbazi, H., et al. Resiliency, morphology, and entropic transformations in high-entropy oxide nanoribbons.  Science  388, 950-956 (2025). [DOI : 10.1126/science.adr5604]

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CDAC Academic Partner Steven Jacobsen (Northwestern University) presented a plenary lecture and graduate student Hannah Bausch presented a poster detailing her research at the recent Z Fundamental Science Program (ZFSP) Workshop, held August 6-9, 2024 in Albuquerque, NM, home of Sandia National Laboratories and Sandia’s Z Machine. The purpose of this annual workshop is to showcase recent shock compression work performed on Sandia’s Z machine within the ZFSP and to provide guidelines from Z facility personnel on the preparation of proposals for instrument time to carry out basic research in the area of dynamic compression with pulsed power sources.

Steve’s presentation was entitled “Origin of the Ultra-Low Velocity Zones Atop Earth’s Core-Mantle Boundary.”  Hannah’s poster was entitled “Shock-Ramp Compression of (Mg,Fe)O up to Earth’s Core Conditions. CDAC-supported work at Northwestern employs Sandia’s Z machine with specially designed pulse sequences and unique experimental configurations to reach thermodynamic states that are not accessible with either static compression or other dynamic compression methods.  Steve’s and Hannah’s work addresses the properties and evolution of complex structures at Earth’s core-mantle boundary region that have been observed through anomalies in seismic data.

For more on the ZFSP and to view the workshop agenda, see the workshop website.

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Developing equations of state (EOS) for mixtures of gases presents a variety of technical challenges arising from the differences in the physical properties of the components. In the case of the H₂-He system, despite the apparent chemical simplicity of these two-electron systems, the behavior of their mixtures is complicated by nonideal mixing and phase transitions in H₂ at high pressures.

In new work carried out through a collaboration between Sandia National Laboratories and UIC, accurate pressure-density EOS for hydrogen-helium mixures have been determined to 44 GPa, representing greater than fourfold compression. Data obtained using both hypervelocity gas guns and Sandia’s Z machine on precompressed samples, in combination with Brillouin spectroscopy on samples under pressure in the diamond anvil cell,¹ have resulted in equations of state for H₂-He mixtures with less than 10% uncertainty in the density (Fig. 1). This allows discrimination between various possible equation of state models for H₂-He mixtures as well as the benchmarking of proposed planetary models. This work has important implications for understanding the dynamics of gas giant planets and their satellites, as well as the development of experimental techniques on shock compression platforms.

The lead author on this work is  Sakun Duwal, a former CDAC graduate student and now a Principal Technical Staff Member in the Dynamic Material Properties (DMP) Department at Sandia National Laboratories. The DMP research program  is led by Chris Seagle, also a former CDAC graduate student, from the University of Chicago.

¹  Zoller, C. M., M. Ahart, S. Duwal, R. C. Clay III, C. T. Seagle, Y. J. Ryu, S. Tkachev, S. Chariton, V. Prakapenka, and R. J. Hemley, Accurate equation of state of H₂-He binary mixtures up to 5.4 GPa. Physical Review B 108, 224112 (2023).
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Duwal, S., R. C. Clay III, M. D. Knudson, J. Boerner, K. Cochrane, J. Usher, D. Dolan, B. Farfan, C. de La Cruz, J. Banasek, C. T. Seagle, R. Hacking, S. Payne, C. Zoller, M. Ahart, and R. J. Hemley, Extreme compression of planetary gases: High-accuracy pressure-density measurements of hydrogen-helium mixtures above fourfold compression. Physical Review B, 109, 104102 (2024).

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Microcrystalline zirconium carbide exhibits lattice expansion due to defect accumulation in two distinct regimes, which differs from the behavior of oxide materials such as CeO₂. This contrasting behavior is observed across different grain sizes.

CDAC graduate student Jacob Minnette, from the group of Academic Partner Maik Lang at the University of Tennessee, along with collaborators from the Lang group, Oak Ridge National Laboratory, HPCAT, and the GSI Helmholzzentrum and the Technische Universität in Darmstadt, Germany, have published the results of important new work on the behavior of zirconium carbide under heavy ion irradiation. This paper is highlighted on the cover of the issue of the Journal of Applied Physics in which it appears.

Zirconium carbide (ZrC) is a material that falls within the broader classification of ultra-high temperature ceramic (UHTC) compounds. These materials possess thermomechanical properties that are of interest for a wide variety of emerging energy and aerospace technologies, which often have operating conditions characterized by extreme conditions. In this work, ZrC was studied with synchrotron X-ray diffraction after exposure to energetic heavy ions. Investigations of materials under such intensely ionizing radiation enables a glimpse of their behavior in conditions far from thermodynamic equilibrium.

The effect of irradiation on such ceramic materials is typically concentrated within small point-like defects that lead to crystal lattice swelling and the accumulation of strain, which reaches a saturation limit above a critical ion fluence. In ZrC exposed to 946 MeV Au ions, an unexpected and complex multi-stage defect accumulation trend comprising of initially rapid lattice swelling takes place, followed by saturation, before a secondary linear swelling regime is observed. Lattice swelling then continues to increase linearly under irradiation up to the highest fluence evaluated in this study, 6×10¹³ ions/cm².

The origin of this behavior likely originates from the hypostoichiometric nature of ZrC, which is typical of many UHTC compounds. This swelling mechanism was consistently observed for samples prepared with different synthesis methods and is distinct from what is observed with cerium dioxide irradiated under identical conditions (Fig. 1). This study highlights the fact that materials can respond very differently to extreme environments, and that studying defect accumulation under energetic heavy ion irradiation is an important step in the development of more robust materials for energy-related applications.

Minnette, J., E. Williams, W. Cureton, A. Solomon, E. O’Quinn, M. Kurley, R. D. Hunt, C. Park, I. Schubert, C. Trautmann, and M. Lang, Response of ZrC to swift heavy ion irradiation. Journal of Applied Physics, 134, 185901 (2023).

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The Center is pleased to report that as of September 1st, 2022, the following papers have been cited 5,563 times since CDAC was founded in 2003:

1. Ahart, M., M. Somayazulu, P. Dera, H.-k. Mao, R. E. Cohen, R. J. Hemley, R. Yang, H. P. Liermann, and Z. Wu, Origin of morphotropic phase boundaries in ferroelectrics. Nature 451, 545-548 (2008). —839 citations.
2. Somayazulu, M., M. Ahart, A. K. Mishra, Z. M. Geballe, M. Baldini, Y. Meng, V. V. Struzhkin and R. J. Hemley, Evidence for Superconductivity Above 260 K in Lanthanum Superhydride at Megabar Pressures. Physical Review Letters 122, 027001 (2019). —823 citations.
3. Mao, W. L., H.-k. Mao, P. Eng, T. P. Trainor, M. Newville, C. C. Kao, D. Heinz, J. Shu, Y. Meng and R. J. Hemley, Bonding changes in compressed superhard graphite. Science 302, 425-427 (2003). —653 citations.
4. Li, Q., Y. Ma, A. R. Oganov, H. Wang, H. Wang, Y. Xu, T. Cui, H.-k. Mao, and G. Zhou, Superhard monoclinic polymorph of carbon. Physical Review Letters 102, 175506 (2009). —561 citations.
5. Gregoryanz, E., C. Sanloup, M. Somayazulu, J. Badro, G. Fiquet, H.-k. Mao and R. J. Hemley, Synthesis and characterization of a binary noble metal nitride. Nature Materials 3, 294-297 (2004). —550 citations.
6. Young, A. F., C. Sanloup, E. Gregoryanz, S. Scandolo, R. J. Hemley and H.-k. Mao, Synthesis of novel transition metal nitrides IrN2 and OsN2. Physical Review Letters 96, 155501 (2006). —543 citations.
7. Liu, H., I. I. Naumov, R. Hoffmann, N. W. Ashcroft, and R. J. Hemley, Potential high-Tc superconducting lanthanum and yttrium hydrides at high pressure. Proceedings of the National Academy of Sciences USA 114, 1704505114 (2017). —530 citations.
8. Angel, R., M. Bijak, J. Zhao, G. D. Gatta, and S. D. Jacobsen, Effective hydrostatic limits of pressure media for high-pressure crystallographic studies. Journal of Applied Crystallography 40, 26-32 (2007). —506 citations.
9. Zhang, W., A. R. Oganov, A. F. Goncharov, Q. Zhu, S. E. Boulfelfel, A. O. Lyakhov, E. Stavrou, M. Somayazulu, V. B. Prakapenka, and Z. Konôpková, Unexpected stable stoichiometries of sodium chlorides. Science 342, 1502-1505 (2013). —433 citations.
10. Struzhkin, V. V., B. Militzer, W. L. Mao, H.-k. Mao and R. J. Hemley, Hydrogen storage in clathrates. Chemical Reviews 107, 4133-4151 (2007). —402 citations.

Altogether nearly 1800 papers have been published as a direct result of CDAC funding. View all of them here.

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