Phys.org January 12, 2022 Conductive MOFs possess rich compositions with complex architectures, but remain unexplored as nanocrystals, hindering their incorporation into scalable devices. MOFs form via a series of chemical reactions that join metal ions with linker molecules. Researchers at the University of Oregon made iron triazolate nanoparticles by adding a third ingredient, molecules that mimic the linkers, but that can only bind to something on one end. They act like dead-ends for the growing MOF, ensuring it stays small. They behaved differently at different sizes and temperatures. They could tune the materials to behave a certain way, by adjusting […]
Tag Archives: Materials science
Nanotube Fibers Stand Strong – But for How Long Under Stresses and Strains?
SciTech Daily December 29, 2021 By combining atomistic models with kinetic Monte Carlo simulations, researchers at Rice University have shown that a pristine carbon nanotube under ambient working conditions is essentially indefatigable accumulating no structural memory of prior load; over time, it probabilistically breaks, abruptly. However, by using coarse-grained modeling they demonstrated that any practical assemblies of nanotubes, e.g., bundles and fibers, display a clear gradual strength degradation in cyclic tensile loading due to recurrence and ratchet-up of slip at the tube-tube interfaces, not occurring under static load even of equal amplitude. They hope to give researchers and industry a […]
Magnetic ‘hedgehogs’ could store big data in a small space
Nanowerk December 17, 2021 An international team of researchers (USA- Ohio State University, Mexico) used a magnetic microscope to visualize the patterns formed in thin films of manganese germanide. The magnetism in this material follows helices, like the structure of DNA which leads to numerous patterns. The images revealed that in certain parts of the sample, the magnetism at the surface was twisted into a pattern resembling the spikes of a hedgehog, about 50 nanometers in size. The hedgehog patterns could be shifted on the surface with electric currents or inverted with magnetic fields. This foreshadows the reading and writing […]
Redrawing the lines: Growing inexpensive, high-quality iron-based superconductors
Phys.org December 17, 2021 The technique of ion irradiation to enhance the dissipation-free supercurrent in the presence of a magnetic field for type II superconductors is complicated and expensive. An international team of researchers (Japan, USA – Florida State University) has developed an inexpensive, scalable way to produce high-temperature superconductors using grain boundary engineering techniques. They grew iron-based superconductors (FBS) called “potassium-doped BaFe2As2 (Ba122) using molecular beam epitaxy, in which the superconductor is grown on a substrate. It had high pinning efficiency without artificial pinning centers (APCs). Measurements of the thin film’s electrical resistivity and magnetic properties showed that the […]
Soft semiconductors that stretch like human skin can detect ultra-low light levels
Science Daily December 15, 2021 An international team of researchers (USA – Georgia Institute of Technology, Chile) has demonstrated a new level of stretchability for a photodetector made from a synthetic polymer and an elastomer that absorbs light to produce an electrical current. It is up to 200% more stretchable than its original dimension without significantly losing its electric current. They found the right combination of chemical compounds to produce a super-soft material with the ability to generate and conduct electricity when exposed to light and the right ratio for all parts of the semiconductor layer to maintain high performance […]
N-type conductive tin sulfide thin films: Towards environmentally friendly solar cells
Science Daily December 13, 2021 An international team of researchers (Japan, USA – National Renewable Energy Laboratory) has fabricated n-type conductive SnS thin films by impurity doping. Conventional SnS thin films are usually p-type conductive. Thus, SnS thin-film solar cells have been fabricated using a pn heterojunction with p-type SnS thin film and other n-type semiconductor thin films, such as CdS. However, the conversion efficiency of such heterojunction devices is approximately 5%. The SnS thin-film solar cells employing a pn homojunction, which uses SnS thin films for both p-type and n-type layers, is expected to exhibit higher conversion efficiency. Utilizing […]
New copper surface eliminates bacteria in just two minutes
Phys.org December 13, 2021 The ions released from the metal’s surface are toxic to bacterial cells. But this process is slow when standard copper is used. Researchers in Australia used a special copper mold casting process to make the alloy, arranging copper and manganese atoms into specific formations. The manganese atoms were then removed from the alloy using dealloying leaving pure copper full of tiny microscale and nanoscale cavities in its surface. The resulting copper is composed of comb-like microscale cavities and within each tooth of the comb structure are much smaller nanoscale cavities; it has a massive active surface […]
Transforming materials with light
Nanowerk December 8, 2021 Although there are strategies to drastically alter electronic and magnetic properties by optically inducing non-trivial band topologies, emergent spin interactions and superconductivity, methods of coherently engineering optical properties on demand are far less understood. An international team of researchers (Caltech, UC Santa Barbara, South Korea) has demonstrated coherent control and giant modulation of optical nonlinearity in a van der Waals layered magnetic insulator, manganese phosphorus trisulfide (MnPS3). They observed a coherent on–off switching of its optical second harmonic generation efficiency on the timescale of 100 femtoseconds with no measurable dissipation. At driving electric fields of the order […]
New ultrahard diamond glass synthesized
Phys.org November 24, 2021 An international team of researchers (China, USA – Carnegie Institution for Science, Germany, Sweden) has synthesized millimetre-sized samples of transparent, nearly pure sp3 amorphous carbon by heating fullerenes at pressures close to the cage collapse boundary. The material synthesized consists of many randomly oriented clusters with diamond-like short-/medium-range order and possesses the highest hardness, elastic modulus and thermal conductivity observed in any known amorphous material. It also exhibits optical bandgaps tunable from 1.85 eV to 2.79 eV. The ultrahard form of carbon glass with a wealth of potential practical applications for devices and electronics. The use of new […]
‘Super jelly’ can survive being run over by a car (with Video)
Phys.org November 25, 2021 The way materials behave is dependent upon the way molecules are joined by crosslinkers. Researchers in the UK used barrel-shaped molecules called cucurbiturils as crosslinking molecule, like molecular handcuff, which hold two guest molecules that prefer to stay inside the cavity for longer than normal keeping the polymer network tightly linked, allowing for it to withstand compression even at 80% water content. They found that the compressive strength could be easily controlled by simply changing the chemical structure of the guest molecule inside the cavity. To make their glass-like hydrogels, the team chose specific guest molecules […]