Phys.org April 30, 2018 The ability to self-assemble, reconfigure and disassemble in response to chemical signals is a common trait in biological materials, but not in manmade ones. A team of researchers in the US (City University of New York, UC Irvine) started with the base molecule naphthalenediimide (NDI), which is an organic semiconductor, and selectively modified it on both sides by exposing to biochemical signals in the form of simple amino acids. This process allowed the formation and degradation of nanomaterials with wire-like features capable of conducting electrical signals. By using different amino acids, researchers were able to direct […]
Tag Archives: Materials science
Scientists find a new way to make novel materials by ‘un-squeezing’
Nanowerk May 1, 2018 A team of researchers in the US (NERL, University of Colorado, University of Connecticut, SLAC National Accelerator Laboratory) mixed high-density forms of manganese selenide and manganese telluride that have different crystal structures by sputtering in which fine sprays of atoms were freed from the surfaces of both starting materials and deposited as a thin film on a hot surface, where the new alloy crystallized and grew. The new alloy had the crystal structure of yet another mineral, wurtzite. Finding new routes to synthesize materials that nature cannot make would catalyze progress towards next-generation technologies… read more. […]
Energy conversion: Optical ‘overtones’ for solar cells
Science Daily April 19, 2018 In solar cells the spectral position of the window of light that can be efficiently converted is strongly related to its band-gap. Researchers in Germany measured the charge carrier density created by the absorption of multiple photons in perovskite nanocrystals. The efficiency of this process becomes drastically enhanced when the frequency of the primary light oscillation and frequency of the exciton at the band-gap become equal. The observation of this novel resonance phenomenon for optical excitations in excitonic semiconductors could pave the way for solar cells to more efficiently convert long-wavelength light into usable electric […]
New thermal coatings for spacecraft and satellites developed using metamaterials
Phys.org April 25, 2018 Optical solar reflectors (OSRs) made of quartz tiles designed to reject solar radiation and dissipate the heat that is generated on board satellites, are heavy, fragile, cannot be applied to curved surfaces and add significantly to assembly and launch costs. An international team of researchers (UK, Italy, Denmark) working on Horizon 2020 sponsored space technology project, developed a new meta-OSR coating enabled by the use of metal oxide that has very strong infrared emissivity while retaining a low absorption of the solar spectrum. A ‘smart’ radiator based on their metamaterial design allows tuning of the radiative […]
New research shows how paper-cutting can make ultra-strong, stretchable electronics
Nanowerk April 3, 2018 A team of researchers in the US (SUNY Buffalo, Temple University) inspired by kirigami used nanoconfinement engineering and strain engineering to create tiny sheets of strong yet bendable electronic materials made of a polymer, PthTFB. The nanosheets can be stretched up to 2000% with simultaneously high electrical conductivity, show remarkable electronic and mechanical reversibility and reproducibility under more than 1000 cycle. The conductivity of the nanosheets increases by three orders of magnitude due to the charge‐transfer complex formation between polymer chain and halogen, while the electrical conductance can be maintained over the entire strain regime. The […]
Crash! Scientists explain what happens when nanoparticles collide
Eurekalert April 4, 2018 To understand the forces that control energy transport at the nanoscale, researchers at SUNY Buffalo focused on small nanoparticles — those with diameters of 5 to 15 nanometers. They found that in collisions, particles of this size behave differently depending on their shape. Nanoparticles with crystal facets transfer energy well, making them an ideal component of materials designed to harvest energy; nanoparticles that are rounder in shape, with amorphous surfaces, adhere to nonlinear force laws making them especially useful for shock mitigation; the behavior of nanoparticles with sharp edges varies depending on sharpness of the edges […]
Engineers turn plastic insulator into heat conductor
Science Daily March 30, 2018 Previously engineered ultradrawn nanofibers from a standard sample of polyethylene could only dissipate heat along the length of each polymer chain. A team of researchers in the US (MIT, Argonne National Laboratory) developed a new way to engineer a polymer conductor using oxidative chemical vapor deposition, whereby two vapors are directed into a chamber and onto a substrate, where they interact and form a film creating rigid chains of polymers, rather than the twisted, spaghetti-like strands in normal polymers. 2 square centimeter samples they produced were able to conduct heat at about 2 watts per […]
Breakthrough in circuit design makes electronics more resistant to damage and defects
Physorg March 9,2018 An international team of researchers (USA – UT Austin, City College of New York, City University of New York, Israel) used nonlinear resonators to mold a band-diagram of the circuit array which was designed so that a change in signal intensity could induce a change in the band diagram’s topology. For low signal intensities, the electronic circuit was designed to support a trivial topology, and therefore provide no protection from defects. In this case, as defects were introduced into the array, the signal transmission and the functionality of the circuit were negatively affected… read more. TECHNICAL ARTICLE
The quantum states on the surface of conducting materials can strongly interact with light
Physorg March 9, 2018 Researchers in Singapore show that Dirac semimetals are unusual in that they possess a very optically active surface due to the peculiar Fermi arc states. Surface absorption depends heavily on the polarization of light, being 100 to 1,000 times stronger when light is polarized perpendicular—rather than parallel—to the crystal’s rotational axis. This strong anisotropy offers a way of optically investigating and probing the topological surfaces states of Dirac semimetals which could host unusual opto-electronic behavior that goes beyond conventional materials… read more. TECHNICAL ARTICLE
A treasure trove for nanotechnology experts
Eurekalert March 6, 2018 Starting from 108,423 unique, experimentally known 3D compounds, an international team of researchers (Switzerland, Lithuania) has identified a subset of 5,619 compounds that appear layered according to robust geometric and bonding criteria. Out of those 1,825 compounds are either easily or potentially exfoliable. For a subset of 258 compounds, they explored vibrational, electronic, magnetic and topological properties, identifying 56 ferromagnetic and antiferromagnetic systems, including half-metals and half-semiconductors. The research paves the way for groundbreaking technological applications… read more. TECHNICAL ARTICLE