EurekAlert February 15, 2021 An international team of researchers (UK, Greece, USA – Rice University, Italy) identified and investigated different geometries of line defects in graphene and molybdenum disulfide such as standing collapsed wrinkles, folded wrinkles, and grain boundaries that exhibit distinct strain and doping. They determined the influence of the defects on local stiffness. For wrinkles of similar height, the stiffness of graphene was found to be higher than that of molybdenum disulfide by 10–15% due to stronger in-plane covalent bonding. Defects in graphene predominantly show compressive strain and increased carrier density. Defects in molybdenum disulfide predominantly show tensile […]
Tag Archives: Advanced materials
Wafer-scale production of graphene-based photonic devices
Science Daily February 11, 2021 Graphene has been recently proposed to be integrated with silicon photonics to meet the challenges of next generation optical communication to increase the available bandwidth while reducing the size, cost, and power consumption of photonic integrated circuits. An international team of researchers (Italy, UK) focused on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. They reported on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency […]
Researchers from NUS create ‘whirling’ nano-structures in anti-ferromagnets
EurekAlert February 4, 2021 Special magnetic nano-patterns in anti-ferromagnets that are shaped as whirls or vortices would be quite useful, as they are very stable structures and can potentially be moved along magnetic ‘race tracks’ at speeds of a few kilometres per second. To realize anti-ferromagnetic whirls an international team of researchers (Singapore, UK, USA – University of Wisconsin) combined high-quality film synthesis from materials engineering, phase transitions from physics and topology from mathematics. To grow these materials they fired a laser at iron-oxide. By using ultra-short pulses of laser, they created a hot vapour of atomic particles that formed […]
Defects may help scientists understand the exotic physics of topology
Science Daily January 22, 2021 Researchers at the University of Illinois engineered metamaterials to include defects to show that defects and structural deformations can provide insights into a real material’s hidden topological features. They experimentally demonstrated that disclination defects can robustly trap fractional charges in topological crystalline insulators (TCI) metamaterials, and the trapped charge can indicate non-trivial, higher-order crystalline topology even in the absence of any spectral signatures. They uncovered a connection between the trapped charge and the existence of topological bound states localized at these defects. By testing the robustness of these topological features when the protective crystalline symmetry […]
Shapeshifting crystals: Varying stability in different forms of gallium selenide monolayers
Phys.org December 24, 2020 Gallium selenide monolayer has been recently discovered to have an alternative crystal structure and has diverse potential applications in electronics. Researchers in Japan studied the structural stability and electronic states of GaSe monolayer with trigonal-antiprismatic (AP) structure by first-principles calculations. The AP-phase GaSe monolayer was found stable, and the differences in energy and lattice constant were small when compared to those calculated for a GaSe monolayer with conventional trigonal-prismatic (P) structure which was found to be the ground state. Moreover, it was revealed that the relative stability of P-phase and AP-phase GaSe monolayers reverses under tensile […]
Stretching diamond for next-generation microelectronics
Science Daily December 31, 2020 An international team of researchers (Hong Kong, Taiwan, China, USA – UC Berkeley, Lawrence Berkeley National Laboratory, MIT) microfabricated single-crystalline diamond bridge structures with ~1 micrometer length by ~100 nanometer width and achieved sample-wide uniform elastic strains under uniaxial tensile loading at room temperature. They demonstrated deep elastic straining of diamond microbridge arrays. The ultra large, highly controllable elastic strains can fundamentally change the bulk band structures of diamond, including a substantial calculated bandgap reduction as much as ~2 electron volts. Their findings have shown the potential of strained diamonds as prime candidates for advanced […]
Active camouflage artificial skin in visible-to-infrared range
Phys.org December 2, 2020 Researchers in South Korea have developed a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with active cooling and heating. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt […]
Quantum nanodiamonds may help detect disease earlier
Science Daily November 25, 2020 Researchers in the UK investigated fluorescent nanodiamonds as an ultrasensitive label for in vitro diagnostics, using a microwave field to modulate emission intensity and frequency-domain analysis to separate the signal from background autofluorescence, which typically limits sensitivity. Focusing on the widely used, low-cost lateral flow format as an exemplar, they achieved a detection limit of 8.2 × 10−19 molar for a biotin–avidin model, 105 times more sensitive than that obtained using gold nanoparticles. Single-copy detection of HIV-1 RNA can be achieved with the addition of a 10-minute isothermal amplification step. This ultrasensitive quantum diagnostics platform […]
Grabbing Viruses Out of Thin Air
Asia Research News November 25, 2020 An international team of researchers (Japan, China, UK) review the state of the art of research on biosensor materials for virus detection. Topics covered include a general description of the principles for virus detection, a critique of the experimental work dedicated to various virus sensors, a summary of their detection limitations. They examined the piezoelectric sensors used for the detection of human papilloma, vaccinia, dengue, Ebola, influenza A, human immunodeficiency, and hepatitis B viruses. Magnetostrictive sensors for the detection of bacterial spores, proteins, and classical swine fever are covered. Progress related to early detection […]
Researchers decipher structure of promising battery materials
MIT News November 23, 2020 MOFs’ extraordinary combination of porosity and conductivity opened the possibility of new applications in batteries, fuel cells, supercapacitors, electrocatalysts, and specialized chemical sensors. Because of the chemical bonds within the MOFs it has been difficult to grow crystals that were large enough for study to figure out their exact molecular structure and how it influences the material’s properties. An international team of researchers (USA – MIT, University of Oregon, University of Connecticut, Purdue University, China, Sweden) has found a way to control the growth of crystals of several kinds of MOFs enabling the team to […]