MIT News September 30, 2019 Shape-morphing structured materials have the ability to transform a range of applications. However, their design and fabrication remain challenging due to the difficulty of controlling the underlying metric tensor in space and time. A team of researchers in the US (MIT, Draper Laboratory, Boston University) exploited a combination of multiple materials, geometry and 4D printing to create structured heterogeneous lattices that overcome this problem. The printable ink’s elastic modulus and coefficient of thermal expansion can be precisely controlled. Multiplexed bilayer ribs were designed to control extrinsic curvature and enable wide range of 3-dimensional shape changes […]
Category Archives: Advanced materials
New liquid crystals allowing directed transmission of electricity synthesized
Science Daily October 1, 2019 Researchers in Germany have synthesized novel liquid crystals in which the molecules align in a self-assembly process to form columns when it is cooled slowly. The columns conduct electrical energy by electrons along their whole length. The materials can serve as organic, liquid crystalline “power cables” and provide targeted electricity transmission in electronic components. The liquid crystalline power cable will heal entirely by itself if it ruptures. If a single molecule is stimulated by exposure to UV light, it will glow in response. If the concentration of the molecule increases, this effect disappears only to […]
Researchers synthesize ‘impossible’ superconductor
Phys.org October 1, 2019 The superconductors known today can only work at very low temperatures and extremely high pressures. As an alternative to metallizing hydrogen, an international team of researchers (China, USA – SUNY Stony Brook) placed a microscopic sample of the metal cerium into a diamond anvil cell, along with a chemical that releases hydrogen and heated with a laser. The cerium sample was squeezed between two flat diamonds to enable the pressure needed for the reaction. As the pressure grew, cerium hydrides with a progressively larger proportion of hydrogen formed in the reactor – CeH2, CeH3, etc. Through […]
MIT engineers develop “blackest black” material to date
MIT News September 12, 2019 The material reported by researchers at MIT is made from vertically aligned carbon nanotubes that the team grew on a surface of chlorine-etched aluminum foil. The foil captures at least 99.995 percent of any incoming light, making it the blackest material on record. They suspect that it may have something to do with the combination of etched aluminum, which is somewhat blackened, with the carbon nanotubes. In an exhibit called Redemption of Vanity they demonstrated the material by making a brilliantly faceted 16.78 carat diamond appear as a flat, black void by coating it with […]
Pearls: New light on enhancing lightweight armor for soldiers
Science Daily September 16, 2019 The bulk of the material created by researchers at SUNY, Buffalo, is ultrahigh molecular weight polyethylene, or UHMWPE, which is used to make products like artificial hips and guitar picks. Their design is based on the mother of pearl, which mollusks create by arranging a form of calcium carbonate into a structure that resembles interlocking bricks. Like mother of pearl, the researchers designed the material to have an extremely tough outer shell with a more flexible inner backing that is capable of deforming and absorbing projectiles. The material is stiff, strong, tough and has high […]
Researchers use laser light to transform metal into magnet
Phys.org September 16, 2019 Up to now, researchers have only been capable of manipulating the properties already found in a material using light. An international team of researchers (Denmark, Singapore) has shown that when the material is irradiated with laser light, plasmons in the metal disk begin to rotate in either a clockwise or counterclockwise direction. However, these plasmons change the quantum electronic structure of a material, which simultaneously alters their own behavior, catalyzing a feedback loop. Feedback from the plasmons’ internal electric fields eventually causes the plasmons to break the intrinsic symmetry of the material and trigger an instability […]
Conductivity at the edges of graphene bilayers
EurekAlert September 11, 2019 At the edges of graphene bilayers atoms can exist in a quantum spin Hall state (QSH) depending on spin-orbit coupling (SOC). While the QSH state is allowed for ‘intrinsic’ SOC, it is destroyed by ‘Rashba’ SOC. Researchers in India have shown that the interaction between the two types of SOC are responsible for variations in the ways in which graphene bilayers conduct electricity. For nanoribbons of bilayer graphene, whose edge atoms are arranged in zigzag patterns, the bands of electron energies which are allowed and forbidden are significantly different to those found in monolayer graphene. This […]
Engineers Build a Device That Effectively Transforms CO2 Into Liquid Fuel
Science Alert September 8, 2019 Usually people reduce carbon dioxide in liquid electrolyte like salty water. The dissolved salts help convert the gas into a molecule that stores energy. Formic acid is sifted out of the thick briny soup. An international team of researchers (USA – Rice University, Harvard University, Northeastern University, Brookhaven National Laboratory, Saudi Arabia) reports that continuous electrocatalytic conversion of CO2 to pure liquid fuel solutions in cells which utilize solid electrolytes, where electrochemically generated cations (such as H+) and anions (such as HCOO−) are combined to form pure product solutions without mixing with other ions. They […]
Molecule properties change through light
Phys.org September 9, 2019 Researchers in Germany have developed and manufactured a novel molecule called 3-methoxy-9-fluorenylidene which is based on a fluorine scaffold with a methoxy group attached in the shape of a rotational tail. They figured out that the molecule’s magnetic properties are determined by the orientation of the methoxy group, which changes its conformation depending on the kind of light that hits it. It can be used to switched on and off magnetism; it is not brittle like conventional magnets, but flexible and can be processed like plastics. Using this group of atoms, we can study the spin […]
New metamaterial morphs into new shapes, taking on new properties
Science Daily September 11, 2019 Most reconfigurable materials can toggle between two distinct states and require a persistent external stimulus to change from one shape to another and stay that way. Using two-photon lithography a team of researchers in the US (Caltech, GeorgiaTech) designed a silicon-coated lattice with microscale straight beams that bend into curves under electrochemical stimulation, taking on unique mechanical and vibrational properties. They built in defects in the architected material system, based on a pre-arranged design. The material has potential for energy storage systems, provides a novel pathway for development of next generation smart batteries with both […]