It has long been known that the properties of materials are crucially dependent on the arrangement of the atoms that make up the material. For example, atoms that are further apart will tend to vibrate more slowly and propagate sound waves more slowly. Now, researchers from Brookhaven National Laboratory have used Sector 30 at the Advanced Photon Source to discover “topological” vibrations in iron silicide (FeSi). These topological vibration arise from a special symmetrical arrangement of the atoms in FeSi and endow the atomic vibrations with novel properties such as the potential to transmit sound waves along the edge of the materials without scattering and dissipation. Looking to the future one might envisage using these modes to transfer energy or information within technological devices.

Nearly 1800 miles below the Earth's surface, there are large, odd structures lurking at the base of the mantle, sitting just above the core. The mantle is a thick layer of hot, mostly plastic rock that surrounds the core; atop the mantle is the thin shell of the Earth's crust. On geologic time scales, the mantle behaves like a viscous liquid, with solid elements sinking and rising through its depths. These odd structures, known as ultra-low velocity zones (ULVZs), can be studied by measuring how they alter seismic waves that pass through them. But observing is not necessarily understanding. Indeed, no one is really sure what these structures are. Now, Earth scientists utilizing ultra-bright x-rays from the U.S. Department of Energy’s Advanced Photon Source, as well as other experimental techniques, say they know not just what ULVZs are made of, but where they come from.

Recent research efforts carried out at the U.S. Department of Energy’s Advanced Photon Source and National Synchrotron Light Source II have yielded new structural and energetic insights into quantum dot nanoparticles by pairing a new technique for precisely-generating cadmium selenide quantum dots with the x-ray scattering techniques.

There is a great need for rechargeable batteries that are safer and more efficient than the current standard, lithium-ion batteries. One promising area of research is in solid-state electrolytes such as superionic crystals, in which part of the material is solid and part is liquid at the same time, which allows electrical flow. These superionic crystals can also help harvest waste heat to produce electricity with thermoelectric modules. In this work, a superionic crystalline material, CuCrSe2, was bombarded with x-rays at the U.S. Department of Energy’s Advanced Photon Source, and with neutrons at the DOE’s Spallation Neutron Source, to reveal how the copper ions could behave as a liquid. With a better understanding of superionic materials, researchers can get closer to developing better and safer personal electronics.

Researchers used the APS to study a promising class of thermoelectric materials with the goal of converting waste heat into electricity, or replacing mechanical cooling systems that rely on fossil fuels with more environmentally friendly solid-state devices.

A growing body of evidence suggests an intimate connection between electronic nematic phases and high-temperature (high-Tc) superconductivity. Research carried out at the U.S. Department of Energy’s APS extends our knowledge about that phenomenon.

Revealing the Mechanism of an Otherworldly Metal-Insulator Transition: Hexagonal iron monosulfide (h-FeS), also known as troilite, features an intriguing crystal structure with multiferroic properties that make it a leading candidate for new technologies such as spintronics. Researchers used the U.S. Department of Energy’s APS to investigate that potential.

Buzz about Thermoelectrics Heats Up with Promising New Magnesium-Based Materials: Looking for the next leap in thermoelectric technologies, researchers using three U.S. Department of Energy research facilities gained new fundamental insights into two magnesium-based materials that have the potential to significantly outperform traditional thermoelectric designs and would also be more environmentally friendly and less expensive to manufacture.

Kitaev Quantum Spin Liquid Revealed by Phonons: An international research team using the U.S. Department of Energy’s Advanced Photon Source has demonstrated a new technique for detecting exotic quantum states in crystalline materials, demonstrating that phonons can be used to identify quantum spin liquids and other quantum states, providing scientists a powerful new tool for probing a wide variety of promising materials for these exotic phenomena.

Research Unearths Obscure Heat Transfer Behaviors: Researchers using data from investigations at two U.S. Department of Energy x-ray light sources including the Advanced Photon Source, have discovered a new physics principle governing how heat transfers through materials, and the finding contradicts the conventional wisdom that heat always moves faster as pressure increases.

Scientists have demonstrated that sparse concentrations of nanoparticles can impact the flow of heat energy through solid materials. While this early work was based around a simple ice model, it paves the way for research towards more advanced, complex and efficient thermal insulation materials.