The Spallation Neutron Source and the High Flux Isotope Reactor, located at the Department of Energy’s Oak Ridge National Laboratory, are two of the world’s most powerful neutron research facilities. As 2023 comes to a close, ORNL highlights some of the facilities’ most impactful scientific achievements during fiscal year 2023 and looks forward to facility upgrades to further enable research addressing the most significant scientific challenges.
The United States has recognized the need to continue operating both facilities for many more decades, and with that, significant investments have been prioritized and various construction phases are well underway.
Nearing completion is the SNS Proton Power Upgrade, or PPU, project. In 2023, the SNS accelerator reached a new record-setting power level of 1.7 megawatts after the addition of newly installed cryomodules. The PPU project will ultimately double the design-level threshold from 1.4 megawatts to 2.8, which will enable new types of experiments and provide enough power to operate the Second Target Station, or STS. In addition to the PPU, significant progress has been made to the STS stub, a new tunnel that branches off the SNS’s linear accelerator that will provide neutrons to the STS.
On track for completion in 2024 is the exciting VENUS project. The new state-of-the-art neutron imaging instrument, being built at SNS, will provide researchers with new experiment capabilities that are currently not available in the U.S.
For more than 55 years, HFIR has been indispensable to the nation as an exclusive provider of medical isotopes and for its capabilities in neutron scattering and irradiated materials research. Major upgrades are in development that will extend the reactor’s lifetime for many more decades. The most immediate upgrades will include the HFIR Beryllium Reflector Replacement, and the Cold Guide Hall Extension project that will optimize current beamlines and provide extra space to build new cutting-edge neutron instruments.
This list of top scientific achievements includes journal articles reported in fiscal year 2023 (October 2022 to September 2023) that best showcase the impacts and scientific range of projects that utilized HFIR and SNS. Click on the name of the scientific journal for access to the peer-reviewed publication.
Uncovering and controlling electron charge waves in quantum materials
Nature — Quantum materials, showcasing competing phases, offer complex electromagnetic effects for quantum computing and energy applications. Rice University scientists used neutrons to study charge density waves, or CDW, a collective behavior of charged ions in iron-germanium. Neutrons’ charge-free magnetism facilitated studying intricate magnetic structures, unveiling CDW within a long-range magnetic phase. This discovery deepens insight into quantum effects, refining detection methods and advancing technology. Read more
Work was performed using CORELLI, SNS BL-9.
Spontaneous directional vibrations in cubic germanium-tellurium thermoelectric
Nature Materials — The high temperature thermoelectric material GeTe does not exhibit long-range disorder, but instead develops spontaneous anisotropic, or directional, atomic motions that disrupt thermal conductivity. Understanding dynamic disorder in materials could lead to more energy-efficient solid-state devices, like heat pumps, thermoelectric generators and refrigerators. This work resolves the long-standing disagreement between local and average structure probes. Read more
Work was performed using ARCS, SNS BL-18.
Putting a magnetic spin on neuromorphic computing
Advanced Materials — Neutron scattering helped demonstrate that spin-waves emitted from collective gyration modes in skyrmions form a long-range fractal network. This first direct observation of fractal structure in spin waves offers new insights into the nanoscale dynamics of skyrmions. Skyrmions and incoming spin waves could lead to developments in neuromorphic computing. Read more
Work was performed using GP-SANS, HFIR CG-2.
A new venue for antiferromagnetic spintronics
Advanced Materials — Nickel monosilicide was found to host a special antiferromagnetic state and is stable at very high temperatures, around 700 K. Studies show that the material can switch its magnetic states sharply under a small magnetic field. This makes Nickel monosilicide a good candidate for designing Magneto-resistive RAM devices and magnetic logic devices that use changes in magnetic resistance at moderate magnetic field strengths.
Work was performed using CORELLI, SNS BL-9.
Elucidating electrolyte−electrode interfaces for solid-state batteries with nanometer precision
ACS Energy Letters — Understanding solid-electrolyte interphase, or SEI, formations are crucial for developing safer, cost-effective, high-energy-density batteries. Neutrons revealed the formation of a thin 7-nanometer SEI as the mechanism that makes an ORNL-developed lithium-based solid electrolyte so efficient at charging and discharging. This study establishes a foundation for researching solid-state electrolyte materials in high-capacity, high-energy density batteries.
Work was performed using Liquids Reflectometer, SNS BL-4B.
Noncovalent Interactions Revealed by Neutron Diffraction
Angewandte Chemie International Edition — High-resolution single crystal neutron diffraction studies of non-covalent weak interactions in fluorinated chiral zinc complexes revealed the material’s precise hydrogen atom positions. The resulting unique carbon-hydrogen bond elongation aligns with density functional theory calculations. These findings have practical applications in designing molecules, binding small molecules to larger ones and understanding different reaction pathways.
Work was performed using TOPAZ, SNS BL-12.
Revealing the relationship between liquid fragility and medium-range order in silicate glass
Nature Communications — Fundamental aspects of the nature of glass transitions are unknown and have an impact on industrial glass production. Neutron studies on aluminosilicate glasses revealed correlations between “fragility” and medium-range distance structural order. Fragility in glass refers to glass formation, or the change of viscosity at the glass transition temperature. Understanding this relationship aids in designing glass formulations with optimized properties for melting, forming and relaxation.
Work was performed using NOMAD, SNS BL-1B.
Protein Arrangement in Metal-Organic Framework
Nature Communications — Small-angle neutron scattering was used to study molecular interactions of proteins encapsulated in metal-organic framework, or MOF, nanopores. The MOF features a unique bi-metal composition, high surface area and tunable pore size, making the material ideal for versatile applications such as gas storage, catalysis and drug delivery.
Hidden Local Symmetry Breaking for Understanding the Peculiar Magnetism in Co3Sn2S2
Journal of the American Chemical Society — Magnetic Weyl semimetals offer a promising frontier for condensed matter research and electronic devices. Neutron studies of a cobalt-tin-sulfure material revealed hidden symmetry breaking at the local scale along with ferromagnetic order that influences structural complexity, magnetism, and topological properties. This discovery clarifies previously puzzling magnetic behaviors, emphasizing the importance of understanding local structures for advancing topological semimetals and kagome magnets.
Understanding the Re-entrant Phase Transition in a Non-magnetic Scheelite
Journal of the American Chemical Society — Thallium ions (Tl+ 6s2) have unique lone pairs of electrons that play a crucial role in the reentrant phase behavior of TlReO4, and chemical doping can tune the behavior of these electrons. This discovery has broad implications for applications in catalysis and materials containing similar ions. Neutron scattering was used to uncover structural changes in thallium ions that revealed a link between Tl+ lone pairs and symmetry during heating.
Understanding fluoride salt intrusion in nuclear-grade graphite
Carbon — Neutron imaging unveiled molten salt infiltration in nuclear-grade graphite, revealing significantly lower salt coverage (0.98%) in historic-grade graphite compared to porous graphite with 20%. This nondestructive technique offers insights into salt distribution, advancing knowledge about the link between graphite microstructure and salt penetrability. These findings guide materials selection for molten salt reactors and enhancing reactor design.
Work was performed using MARS, HFIR CG-1D.
Diving into dynamic magnetism in synthetic honeycomb spin ice
Nature Communications — In the vertices of a honeycomb-shaped synthetic spin ice material, magnetic charges generate monopoles that move freely through the lattice. Unlike atomic spin ice, the artificial honeycomb material is thermally tunable and has a permalloy lattice that maintains perpetual dynamics without external forces. Neutron spin echo spectroscopy studies suggest that honeycomb spin ice dynamics involve quasi-particles, resembling both magnetic monopoles and magnons.
Work was performed using Neutron Spin Echo, SNS BL-15.
HFIR and SNS are DOE Office of Science user facilities.
UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. — Jeremy Rumsey