EurekAlert March 4, 2020 Accurate predictions of the temperature when embrittlement occurs is crucial to design conducting polymers that are used in next-generation flexible electronics. An international team of researchers (USA – Pennsylvania State University, Germany) found a way to measure glass transition temperatures by keeping track of the mechanical properties as embrittlement occurs, laying the foundation for understanding the relationship between the glass transition and structure. Follow-up studies then determined the glass transition for 32 different polymers by measuring mechanical properties as a function of temperature. They showed the simple relationship between the chemical structure and the glass transition […]
Category Archives: Materials science
New encapsulation technique protects electronic properties of sensitive materials
Science Daily January 29, 2020 Indium selenide and gallium selenide are emerging two-dimensional semiconductors with appealing electronic properties. However, they are sensitive to air and device fabrication processes which induce structural damage and hamper their intrinsic properties. An international team of researchers (USA -Columbia University, Germany, Japan) has demonstrated an encapsulating technique where two layers of hBNhexagonal boron nitride (hBN) entirely covers the 2D layers of InSe and GaSe passivating them from the environment and isolating them from the charge disorder at the SiO2 surface. They demonstrated a strong and reproducible photo response and long-term stability. The technique can open […]
Scientists develop ceramic materials that are IR-transparent
Nanowerk December 30, 2019 An international team of researchers (Ukraine, Russia, China) developed Y2O3-MgO nanocomposite ceramics with uniform distribution of two phases, microhardness over 11 GPa, and average grain size of 250 nm. It is capable of transmitting over 70% of IR-range with wavelength up to 6,000 nm. The IR transparency increases with the increasing of sintering temperatures, and top values are reached at 1,300-1,350 °C. This is due to the increase of sample density, grain growth, and the reduction of grain boundary length. Due to the submicron size of the grains and their even distribution in the whole volume […]
An alloy that retains its memory at high temperatures
Science Daily December 3, 2019 In the conventional high-temperature shape memory alloy Ti-Ta, the formation of this phase compromises completely the shape memory effect. Addition of other elements to form Ti-Ta-X alloys often modifies the transformation temperatures. Researchers in Germany used transparent descriptors derived from first-principles calculations to search for new ternary Ti-Ta-X alloys that combine stability and high temperatures. They suggest four alloys with these properties, namely Ti-Ta-Sb, Ti-Ta-Bi, Ti-Ta-In, and Ti-Ta-Sc. Their predictions for the most promising of these alloys, Ti-Ta-Sc, are subsequently fully validated by experimental investigations showing no traces of omega phase after cycling. Their computational […]
Controlling the optical properties of solids with acoustic waves
Science Daily December 2, 2019 So far moderately large changes in the exitons control parameters — temperature, pressure, electric and magnetic fields that can tune excitonic properties have only been achieved under equilibrium conditions and at low temperatures. An international team of researchers (Switzerland, Spain, Germany, USA- Simons Foundation Flatiron Institute, France) has demonstrated the control of excitonic properties using acoustic waves in titanium dioxide at room temperature. To do this, the researchers launched a high-frequency (hundreds of gigahertz), large-amplitude acoustic wave in the material using ultrashort laser pulses. This strategy allows for the dynamical manipulation of the exciton properties […]
New spin directions in pyrite an encouraging sign for future spintronics
Science Daily November 12, 2019 Generating and manipulating out-of-plane spins without applying an external electric or magnetic field has been a key challenge in spintronics. Researchers in Australia demonstrate for the first time that pyrite-type (Pyrite is an iron-sulfide mineral that displays multiple internal planes of electronic symmetry) crystals can host unconventional energy- and direction-dependent spin textures on the surface, with both in-plane and out-of-plane spin components, in sharp contrast to spin textures in conventional topological materials. The findings provide a platform for experimentalists to detect and exploit unconventional surface spin textures in future spin-based nanoelectronic devices…read more. Open Access […]
Cracking the mystery of nature’s toughest material
Science Daily October 23, 2019 Nacre (mother-of-pearl) that lines the insides of mussel and other mollusk shells is known as nature’s toughest material. An international team of researchers (USA – University of Michigan, Australia, Germany) found that nacre is made of microscopic bricks made of a mineral called aragonite, laced together with a mortar made of organic material. The tablets remain separate, arranged in layers. When stress is applied to the shells, the mortar squishes aside and the tablets lock together, forming a solid surface. When the force is removed, the structure springs back, without losing any strength or resilience. […]
Refrigerator works by twisting and untwisting fibres
Physics World October 14, 2019 An international team of researchers (China, USA – UT Dallas, Georgia Southern University, industry, Brazil) studied the cooling effects of twist and stretch changes in twisted, coiled and supercoiled fibres of natural rubber, nickel-titanium and polyethylene fishing line. In each material, they observed a surface cooling as high as 16.4 °C, 20.8 °C, and 5.1 °C respectively. Analysis revealed changes in molecular structures associated with the transition from low to high entropy phases. They built a device from a three-ply nickel-titanium wire cable, which cooled a stream of running water by as much as 7.7 […]
‘The Alexa of chemistry’: NSF puts VCU and partners on fast track to build open network
EurekAlert September 12, 2019 Currently, there is no shared network or central portal where molecular scientists and engineers can harness artificial intelligence and data science tools to build models to support their needs. There is no standard way to represent — or predict — molecular performance. Under the NSF Convergence Accelerator program it has funded a multi-university pilot project seeking to use artificial intelligence to help scientists come up with the perfect molecule for everything from a better shampoo to coatings on advanced microchips. They will develop a central platform for collecting data, creating molecular imprints and developing algorithms for […]
At the edge of chaos, powerful new electronics could be created
Science Daily September 3, 2019 An international team of researchers (The Netherlands, USA – Pennsylvania State University, Spain, UK) observed a structural transition in the ferroelastic material barium titanate. The unit cells in these crystals are elongated creating an elastic strain that reduces the crystal stability. Increasing the temperature increases the entropy in the material. Cooling the material reduces the periodicity of the domains by repeated halving. They have shown that the behaviour observed in the ferroelastic barium titanate is generic for ferroic materials. Doubling of domains creates a structure similar to the bifurcating dendrites connecting the pyramidal cells in […]