Nanowerk January 6, 2023 To explore how coal can be converted into valuable materials like graphite researchers at Ohio University simulated the substances in computer software. They created a simplified “coal” that consisted of only carbon atoms in random position and exposed them to pressure and high temperature — about 3,000 Kelvin. They formed sheets, but the carbon atoms didn’t entirely develop simple, six-carbon rings. A fraction of the rings had five carbons; others had seven. While six-carbon rings were flat, five- and seven-membered carbon rings puckered. The conditions in these simulations caused the sheets to curve in on themselves […]
Category Archives: Materials science
Electronic bridge allows rapid energy sharing between semiconductors
Phys. org January 4, 2023 A team of researchers in the US (SLAC National Accelerator Laboratory, Stanford University, UC Berkeley) studied devices consisting of stacked monolayers of WSe2 and WS2. They found that the WSe2 layer heated up, as expected, and the WS2 layer also heated up in tandem, suggesting a rapid transfer of heat between layers. By contrast, when they didn’t excite electrons in the WSe2 and heated the heterostructure using a metal contact layer instead, the interface between WSe2 and WS2 transmitted heat very poorly, confirming previous reports. It was surprising to see the two layers heat up […]
Researchers show a new way to induce useful defects using invisible material properties
Nanowerk December 23, 2022 Researchers at the University of Illinois constructed a Dirac material consisting of a chain of magnetic-mechanical resonators and demonstrated that when any of these “atoms” was mechanically excited the excitation spread to the rest of the crystal, just like electrons injected into a semiconductor. After demonstrating that a completely uniform Dirac metamaterial does not allow mechanical excitations to pass through, they introduced a specific set of nonlinearities into the system. This new property added sensitivity to the level of the mechanical excitation and could subtly change the resonance energy of the magneto-mechanical atoms. With the right […]
Materials science: A rough start can lead to a strong bond
Science Daily December 21, 2022 Researchers in Japan developed a cheap and simple process to create nanoscale structures on the surface of galvanized steel, which is commonly used in the automotive industry, that provided a more conducive interface for attaching injection-molded polymers. They used hot water treatment (HWT) to produce a nanoscale needle-like structure on the zinc coating surface to enhance the joining strength and obtained strong joints of galvanized high-strength steel (GHSS) and polybutylene terephthalate (PBT) with minimal damage to the zinc coating. The effects of HWT conditions on the tensile shear strength were evaluated and the optimized strength […]
Scientists turn single molecule clockwise or counterclockwise on demand
Phys.org December 21, 2022 Complexes containing rare-earth ions attract great attention for their technological applications ranging from spintronic devices to quantum information science. While charged rare-earth coordination complexes are ubiquitous in solution, they are challenging to form on materials surfaces that would allow investigations for potential solid-state applications. A team or researchers in the US (Argonne National Laboratory, Ohio University, University of Illinois) has demonstrated formation and atomically precise manipulation of rare-earth complexes on gold surface. Although they are composed of multiple units held together by electrostatic interactions, the entire complex rotates as a single unit when electrical energy is […]
Unexpected speed-dependent friction with graphene
Nanowerk, December 6, 2022 Graphene is being examined with a view to potential use as a lubricating layer. If it is applied to a platinum surface, it has a significant impact on the measurable friction forces. An international team of researchers (Israel, Switzerland) has reported that, in this instance, the friction depends on the speed at which the tip of an atomic force microscope (AFM) is moved across the surface. In conjunction with the platinum substrate, graphene no longer forms only the hexagonal honeycomb pattern of carbon atoms and instead forms Moiré superlattices. The surface is then no longer completely […]
How to fire projectiles through materials without breaking anything
Nanowerk November 28, 2022 Researchers in Austria bombarded ultrathin materials with highly charged ions to explain why sometimes the projectile penetrates the material layer without any noticeable change in the material and sometimes the material layer around the impact site is also completely destroyed. They found that it is not the momentum of the projectile that is mainly responsible for the holes, but its electric charge. When an ion with multiple positive charge hits the material layer, it attracts a larger number of electrons and takes them with it leaving a positively charged region in the material layer. Graphene’s high […]
Electrokinetic mining technology for recovering rare earth elements from weathering crusts
Phys.org November 17, 2022 Ion-adsorption deposits, which form within weathering crusts, supply more than 95% of the scarce global heavy rare earth elements (HREE) demand. Deposits are currently mined via ammonium-salt-based leaching techniques that are responsible for severe environmental damage and show low recovery efficiency. Researchers in China have designed an innovative rare earth elements (REE) mining technique, electrokinetic mining (EKM), which enabled green, efficient and selective recovery of REEs from weathering crusts. Its feasibility was demonstrated via bench-scale, scaled-up and on-site field experiments. Compared with conventional techniques, EKM achieved ~2.6 times higher recovery efficiency, an ~80% decrease in leaching […]
New strategy to effectively prevent component failures in metals
Phys.org November 11, 2022 Eliminating grain boundaries (GBs) is a primary approach to resisting high-temperature creep in metals which is responsible for component failures at high temperatures. Researchers in China found that grain boundaries in the nanograined single-phased alloy could be effectively stabilized through structural relaxation, and the creep performance of the alloy could be significantly enhanced at elevated temperatures. They demonstrated a creep resistance, with creep rates of ~10–7 per second under gigapascal stress at 700°C (~61% melting point), outperforming that of conventional superalloys. They plan to extend this principle to other engineering alloy families for high-temperature applications, including […]
Discovery of a fundamental law of friction leads to new materials that can minimize energy loss
Nanowerk November 3, 2022 By performing measurements on bulk graphite, and on epitaxial graphene films on SiC with different stacking orders and twisting, as well as in the presence of intercalated hydrogen an international team of researchers (USA – New York University, Italy, Czech Republic) found that the interfacial transverse shear modulus was critically controlled by the stacking order and the atomic layer–substrate interaction. They demonstrated that the modulus is a pivotal measurable property to control and predict sliding friction in supported two-dimensional materials. Their experiments demonstrated a reciprocal relationship between friction force per unit contact area and interfacial shear […]