Nanowerk July 13, 2023 Contrary to topological insulators, topological semimetals possess a nontrivial chiral anomaly that leads to negative magnetoresistance and host to both conductive bulk states and topological surface states with intriguing transport properties for spintronics. Researchers at the University of Minnesota fabricated highly ordered metallic Pt3Sn and Pt3SnxFe1-x thin films via sputtering technology. Systematic angular dependence (both in-plane and out-of-plane) study of magnetoresistance presented surprisingly robust quadratic and linear negative longitudinal magnetoresistance features for Pt3Sn and Pt3SnxFe1-x, respectively. They attributed the anomalous negative longitudinal magnetoresistance to the type-II Dirac semimetal phase (pristine Pt3Sn) and/or the formation of tunable […]
Tag Archives: Advanced materials
Physicists develop a metamaterial that can count
Phys.org July 3, 2023 Researchers in the Netherlands have designed irreversible metamaterials that count mechanical driving cycles and store the result into easily interpretable internal states. They extended the designs to aperiodic metamaterials that were sensitive to the order of different driving magnitudes and realized “lock and key” metamaterials that only reach a specific state for a given target driving sequence. The metamaterials were robust, scalable, and extendable, gave insight into the transient memories of complex media, and opened new routes towards smart sensing, soft robotics, and mechanical information processing. Video https://youtu.be/soO2OzbdRzU… read more. TECHNICAL ARTICLE
Scientists develop highly porous materials for electronic and photocatalytic applications
Phys.org July 3, 2023 Porous poly(aryl thioether)s offer stability and electronic tunability by robust sulfur-aryl conjugated architecture, but synthetic access is hindered due to limited control over the nucleophilic nature of sulfides and the air sensitivity of aromatic thiols. An international team of researchers (South Korea, Saudi Arabia) has developed a regioselective synthesis of highly porous poly(aryl thioether)s through polycondensation of perfluoroaromatic compounds with sodium sulfide. The temperature-dependent para-directing formation of thioether linkages led to a stepwise transition of the polymer extension into a network, thereby allowing fine control of the porosity and optical band gaps. The resulting porous organic […]
Researchers develop an extreme environment-resistant nanopaper
Phys.org June 21, 23 Researchers in China developed a kind of nacre-inspired bacterial cellulose (BC)/synthetic mica (S-Mica) nanopaper with excellent mechanical and electrical insulating properties that has excellent tolerance to extreme conditions. The nanopaper exhibited excellent mechanical properties, including high tensile strength (375 MPa), outstanding foldability, and bending fatigue resistance. S-Mica arranged in layers endowed the nanopaper with remarkable dielectric strength (145.7 kV mm−1) and ultralong corona resistance life. The nanopaper was highly resistant to alternating high and low temperatures, UV light, and atomic oxygen… read more. TECHNICAL ARTICLE
This salty gel could harvest water from desert air
MIT News June 15, 2023 Hygroscopic hydrogels are emerging as scalable and low-cost sorbents for atmospheric water harvesting, dehumidification, passive cooling, and thermal energy storage. However, devices using these materials still exhibit insufficient performance, partly due to the limited water vapor uptake of the hydrogels. Researchers in Germany synthesized hygroscopic hydrogels with extremely high salt loadings by tuning the salt concentration of the swelling solutions and the cross-linking properties of the gels. This resulted in unprecedented water uptakes at relative humidity. At 30% RH, the uptake exceeded previously reported water uptakes of metal–organic frameworks by over 100% and of hydrogels […]
New material transforms light, creating new possibilities for sensors
Phys.org June 12, 2023 Hybrid structures formed between organic molecules and inorganic quantum dots can accomplish unique photophysical transformations by taking advantage of their disparate properties. However ,the electronic coupling is typically weak, leading photoexcited charge carriers to spatially localize to the dot or to a molecule at its surface. A team of researchers in the US (University of Utah, University of Colorado, UC Riverside, UT Austin) has shown that by converting a chemical linker that covalently binds anthracene molecules to silicon quantum dots from a carbon–carbon single bond to a double bond, they accessed a strong coupling regime where […]
Lightning Bolt Deposits a Strange Mineral Never Seen on Earth Before
Science Alert April 15, 2023 Phosphate minerals such as those in the apatite group tend to be the dominant forms of phosphorus in minerals on the Earth’s surface. Phosphate can be reduced to phosphides during high-energy events, such as lightning and impacts. An international team of researchers (Italy, USA – University of South Florida) has shown that, in addition to formation of metal phosphides, a new compound was formed by lightning in a fulgurite from New Port Richey, Florida.. A calcium phosphite material, ideally CaHPO3, was found in spherules mainly consisting of iron silicides that formed by lightning-induced fusion of […]
The quantum spin liquid that isn’t one
Phys.org April 18, 2023 For two decades, it was believed that a possible quantum spin liquid was discovered in a synthetically produced material. In this case, it would not follow the laws of classical physics even on a macroscopic level, but rather those of the quantum world. An international team of researchers (Austria, Spain) has shown that the promising material, κ-(BEDT-TTF)2Cu2(CN)3, is not the predicted quantum spin liquid, but a material that can be described using known concepts. They were able to precisely map the spin-gapped phase through the Mott transition by ultrahigh-resolution strain tuning. Through transport experiments they revealed […]
Scientists use computational modeling to design “ultrastable” materials
MIT News April 4, 2023 High-throughput screening of hypothetical metal-organic framework databases can uncover new materials, but their stability in real-world applications is often unknown. Researchers at MIT leveraged community knowledge and machine learning models to identify MOFs that are thermally stable and stable upon activation. They separated the MOFs into their building blocks and recombined them to make a new hypothetical MOF database of over 50,000 structures with orders of magnitude more connectivity nets and inorganic building blocks than were present in prior databases. This database showed a 10-fold enrichment of ultrastable MOF structures that were stable upon activation […]
Experiment unlocks bizarre properties of strange metals
Science Daily March 13, 2023 An iternational team of researchers (Japan, USA – University of Cincinnati, Rutgers University) fired gamma rays at an alloy of ytterbium to observe its unusual electrical behavior. They studied the charge fluctuations of the strange metal phase of β-YbAlB4 as a function of temperature and pressure they found that the usual single absorption peak in the Fermi-liquid regime splits into two peaks upon entering the critical regime. The team interpreted this spectrum as a single nuclear transition, modulated by nearby electronic valence fluctuations whose long time scales are further enhanced by the formation of charged […]