Phys.org November 7, 2018 Researchers in Japan developed a terahertz pulse generator that delivered ultra-short and highly intense terahertz pulses across a pair of gold antennas. The pulses created an electric field in the material composed of germanium, antimony and tellurium (GST) sample, comparable to that of an electrically switched device. It greatly reduced the heat diffusion because of the extremely short duration of terahertz pulses enabling fine control over the rate and direction of GST crystallization. After a certain point when terahertz pulses were increased, crystal conductivity rapidly sped up instead of rising in line with the increase in […]
Tag Archives: Materials science
Uncovering secret structure to explosives
Lawrence Livermore National Laboratory October 17, 2018 In most high explosives, detonation is initiated through a process where pores get compressed by a shockwave. Researchers at the Lawrence Livermore National Laboratory found that in an explosive compound called HMX when pores are at the surface, they speed up the reaction, if a shockwave hits a number of surface pores at once, they bootstrap each other. While they showed that many small pores can work together to accelerate one another’s burning, they also were able to identify a threshold where pores become so small that the reaction is extinguished. This examination […]
Researchers switch material from one state to another with a single flash of light
SLAC National Accelerator Laboratory October 19,2018 In tantalum disulfide the charge density waves are all oriented in the same direction in the alpha state. A team of researchers in the US (MIT, SLAC National Accelerator, Harvard University) zapped a thin crystal of tantalum disulfide with a very brief laser pulse. They found that some of the waves flipped into a beta state with a different electron orientation, and the alpha and beta regions were separated by domain walls. A second flash of light dissolved the domain walls and returned the material to its pure alpha state. They could fine-tune the […]
Research on light-matter interaction could improve electronic and optoelectronic devices
Eurekalert October 10, 2018 To study low dimensional quantum materials and their quantum effects an international team of researchers (USA – Rensselaer Polytechnic Institute, Florida State University, UC Berkeley, Japan) built a device by stacking multiple atomically thin materials together, including graphene, boron nitride and tungsten diselenide. They showed that as the density of the exciton increases, more electrons and holes pair together, forming four-particle and even five-particle excitonic complexes. They revealed the true biexciton state, a unique four-particle complex responding to light and the nature of the charged biexciton, a five-particle complex. The research gives rise to fundamental understanding […]
Flowing salt water over this super-hydrophobic surface can generate electricity
Eurekalert October, 3, 2018 Researchers at UC San Diego created a surface so hydrophobic that it enables water (and any ions it carries) to flow faster when passing over it; it holds a negative charge, so a rapid flow of positive ions in salt water with respect to this negatively charged surface results in an electrical potential difference, creating an electrical voltage. The surface was made by etching tiny ridges into a silicon substrate and then filling the ridges with oil. The proof-of-concept work could lead to the development of new power sources for lab-on-a-chip platforms and other microfluidics devices…read […]
Scientists discover a ‘tunable’ novel quantum state of matter
Nanowerk September 12, 2018 An international team of researchers (China, USA – Boston College, Princeton University, Lawrence Berkeley National Laboratory, Taiwan) arranged atoms on the surface of crystals in many different patterns on ferromagnet to explore the associated phenomena. The electrons hovering above their atoms aligned in a straight line, with two-fold symmetry ignoring the lattice symmetry. When a magnetic field was applied they could turn one line in any direction they chose rotating the line of electrons just by controlling the magnetic field around them. Anisotropy was 100 times more than what theory predicts. The findings open enormous possibilities […]
Electromagnetic radiation protection shields developed
Phys.org September 7, 2018 Normally, heavy elements are used as the material for electromagnetic and magnetic shielding, as they efficiently absorb high-energy radiation. Bismuth is the best option in the ratio of the protection efficiency to mass-size parameters. An international team of researchers (Russia, Belarus) studied the dependency of the bismuth film microstructure and functional properties on the production process regimes and the initial electrolyte composition and determined that electrolyte mixing, temperature, and organic additives exert a noticeable influence on the electrode process of the discharge of Bi3+ions in acid perchlorate electrolyte. The research answers the question of how to […]
Cannibalistic materials feed on themselves to grow new nanostructures
Science Daily August 31, 2018 A team of researchers in the US (Oak Ridge National Laboratory, Pennsylvania State University, Drexel University) has shown that by thermal exposure and electron-beam irradiation, hexagonal TiC single adlayers form on defunctionalized surfaces of Ti3C2 MXene at temperatures above 500 °C, generating new 2D materials Ti4C3 and Ti5C4, with the substrate being the source material. The work could lead to the development of bottom-up synthesis methods using substrates terminated with similar hexagonal-metal surfaces, for controllable synthesis of larger-scale and higher quality single-layer transition metal carbides… read more. Open Access TECHNICAL ARTICLE
Engineered sand zaps storm water pollutants
Science Daily August 30, 2018 To provide a passive, low-cost means of oxidizing substituted phenols, aromatic amines, and other electron-rich organic compounds during infiltration of contaminated waters, an international team of researchers (USA – UC Berkeley, the Netherlands) coated sand with manganese oxide using a new approach involving the room-temperature oxidation of Mn2+ with permanganate. The coated sand effectively oxidized bisphenol A under typical infiltration conditions and sustained reactivity longer than previously described geomedia. The results suggest that it is possible to regenerate the oxidative capacity of manganese oxide-coated sands without excavating stormwater infiltration systems and manganese oxide geomedia may […]
Breaking down band structures
Nanowerk August 22, 2018 A systematic study of symmetry and topology in magnetic materials has been challenging given that there are 1651 magnetic space groups (MSGs). By using an efficient representation of allowed band structures, an international team of researchers (Japan, USA – Harvard University) obtained a systematic description of several basic properties of free electrons in all MSGs in three dimensions, as well as in the 528 magnetic layer groups relevant to two-dimensional magnetic materials. They computed constraints on electron fillings and band connectivity compatible with insulating behavior. Crystalline insulators and topological semimetals could be exploited to use the […]