Nanowerk August 22, 2022 Extensive studies on the structure and relaxation dynamics of glasses have constructed the current classical picture: glasses consist of some ‘soft zones’ of loosely bound atoms embedded in a tightly bound atomic matrix. Recent experiments have found an additional fast process in the relaxation spectra, but the underlying physics of this process remains unclear. Researchers in China combined extensive dynamic experiments and computer simulations and found that the fast relaxation is associated with string-like diffusion of liquid-like atoms, which are inherited from the high-temperature liquids. Even at room temperature, some atoms in dense-packed metallic glasses can […]
Category Archives: Materials science
The best semiconductor of them all?
MIT News July 21, 2022 Among the ultrahigh–thermal conductivity materials, cubic boron arsenide (c-BAs) is predicted to exhibit simultaneously high electron and hole mobilities of >1000 centimeters squared per volt per second. Using the optical transient grating technique, a team of researchers in the US (MIT, University of Houston, UT Austin, Boston College) experimentally measured thermal conductivity of 1200 watts per meter per kelvin and ambipolar mobility of 1600 centimeters squared per volt per second at the same locations on c-BAs samples at room temperature despite spatial variations. Ab initio calculations show that lowering ionized and neutral impurity concentrations is […]
Biodegradable electronic ink for recyclable printed electronics
Nanowerk June 22, 2022 A team of researchers in the US (UC Berkely, Lawrence Berkely National Laboratory) has developed recyclable conductive composites that are introduced for printed circuits formulated with polycaprolactone (PCL), conductive fillers, and enzyme/protectant nanoclusters. Circuits can be printed with flexibility (breaking strain ≈80%) and conductivity (≈2.1 × 104 S m−1). These composites are degraded at the end of life by immersion in warm water with programmable latency. Approximately 94% of the functional fillers can be recycled and reused with similar device performance. The printed circuits remain functional and degradable after shelf storage for at least 7 months […]
Scientists poke holes in liquid to keep airplanes from freezing on a rainy day
Phys.org June 22, 2022 If the nature of the surface is such that it repels liquid, the very act of replenishing the film by spraying liquid on the surface may create vulnerable dry spots due to droplet collisions with the film. The formation of a stable dry spot has only been studied in the inviscid case. An international team of researchers (Russia, Canada) examined the break-up of viscous films, and demonstrated the importance and role of the viscous dissipation in both film and droplet. They proposed a new model to predict the necessary droplet energy to create a dry spot. […]
New, highly tunable composite materials—with a twist
Phys.org June 14, 2022 Researchers at the University of Utah found that they can design “twisted bilayer composite,” from a range of composite materials from moiré patterns created by rotating and stretching one lattice relative to another. As the twist angle and scale parameters vary, these patterns yield myriad microgeometries. Their electrical and other physical properties can change depending on whether the resulting moiré patterns are regularly repeating or non-repeating. According to the researchers their mathematical framework allows for changes in optical, electrical, magnetic, diffusive, and thermal properties with very small changes in the twist angle. New materials can be […]
Clean doping strategy produces more responsive phototransistors
Phys.org June 7, 2022 An international team of researchers (China, USA – SUNY Buffalo) studied and demonstrated the implementation of neutron-transmutation doping (NTD) to manipulate electron transfer. NTD is a controllable in-situ substitutional doping method that utilizes the nuclear reactions of thermal neutrons with the nuclei of the atoms in semiconductors. It provides a new way to dope 2D materials intentionally without extra reagents and it can be introduced into any step during the fabrication of 2D-materials-based devices, or even used post-fabrication. They successfully narrowed the bandgap and increased the electron mobility of SN-doped layered InSe, reflecting a significant improvement. […]
Shining light on a fluid completely changes its dielectric permittivity
Nanowerk June 3, 2022 Researchers in Japan have developed a liquid whose dielectric permittivity can range from 200 to 18,000 in just half a minute when light is shone on it. They combined two molecules – a liquid crystal that has two phases, one with a low and one with extremely high dielectric permittivity. The second molecule is light sensitive. When blue light was shined on the combined molecule, it switched from the low-dielectric-permittivity phase to the high one; when green light was shined on the fluid it reversed the situation, causing it to return to the low-dielectric-permittivity phase. They […]
New route to build materials out of tiny particles
Phys.org May 27, 2022 Creating materials with structure that is independently controllable at a range of scales requires breaking naturally occurring hierarchies. Breaking these hierarchies can be achieved via the decoupling of building block attributes from structure during assembly. An international team of researchers (the Netherlands, USA (University of Michigan, University of Pennsylvania, Canada) demonstrated that shape and interaction decoupling occur in colloidal cuboids suspended in evaporating emulsion droplets. The resulting colloidal clusters serve as “preassembled” mesoscale building blocks for larger-scale structures. They showed that clusters of up to nine particles form mesoscale building blocks with geometries that are independent […]
A new strategy for active metasurface design provides a full 360-degree phase tunable metasurface
Phys.org May 2, 2022 Active metasurfaces have been proposed as one attractive means of achieving high-resolution spatiotemporal control of optical wavefronts, having applications such as LIDAR and dynamic holography. An international team of researchers (South Korea, USA – University of Wisconsin) has developed an electrically tunable metasurface design strategy that operates near the avoided crossing of two resonances, one a spectrally narrow, over-coupled resonance and the other with a high resonance frequency tunability. It displayed an upper limit of 4π range of dynamic phase modulation with no significant variations in optical amplitude, by enhancing the phase tunability through utilizing two […]
A novel insulating state emerges in a 2D material
Nanowerk April 23, 2022 Within the Transition-metal dichalcogenides (TMD) family, iridium ditelluride (IrTe2) is ideally suited for the systematic study of competing factors that can affect a material’s electronic properties. An international team of researchers (USA – Lawrence Berkely National Laboratory, SLAC National Accelerator Laboratory, UC Berkeley, Sandford University, South Korea, Egypt) synthesized bilayer and monolayer IrTe2 samples and characterized their atomic and electronic structures. The analysis of the material showed that monolayer IrTe2 develops a large band gap that’s an order of magnitude larger than is typical for TMD systems, transforming the material into an insulator through the removal […]