Phys.org May 9, 2022 A team of researchers in the US (University of Minnesota, UMass Amherst, UC Santa Barbara) has invented a device called catalytic condenser that allowed them to tune the number of electrons at the surface of the catalyst converting one metal to behave like another. They fabricated the catalytic condenser by combining nano-scale film of alumina with graphene, which could be electronically tuned. The condenser uses a combination of nanometer films to move and stabilize electrons at the surface of the catalyst. The power of the device to stabilize electrons is tunable with varying composition of a […]
Tag Archives: Materials science
Hidden distortions trigger promising thermoelectric property
Science Daily May 9, 2022 Conventional structure transitions occur from a low symmetry state to a higher symmetry state upon warming. An international team of researchers (USA – Northwestern University, Brookhaven National Laboratory, Germany) found an unexpected local symmetry breaking in the tetragonal diamondoid compound silver gallium telluride. Upon warming, it evolved continuously from an undistorted ground state to a locally distorted state while retaining average crystallographic symmetry. This is a rare phenomenon previously referred to as emphanisis. The distorted state, caused by the weak orbital hybridization of tetrahedral Ag atoms, resulted in their displacement of the tetrahedron center and […]
Team demonstrates rare form of electricity in ultra-thin material
Phys.org April 27, 2022 Molybdenum disulfide (MoS2) is known as one of the most promising and robust 2D electronic materials. However, despite theoretical predictions, no ferroelectricity has been experimentally detected in MoS2. An international team of researchers (USA – University of Nebraska, industry, China, France, Luxembourg) has reported the experimental observation of a stable room-temperature out-of-plane polarization ordering in 2D MoS2 layers, where polarization switching is realized by mechanical pressure induced by a tip of a scanning probe microscope. Using this approach, they created the bi-domain polarization states, which exhibit different piezoelectric activity, second harmonic generation, surface potential, and conductivity. […]
Lasers trigger magnetism in atomically thin quantum materials
Science Daily April 20, 2022 Recently two-dimensional moiré superlattices have emerged as a promising platform for quantum engineering. The power of the moiré system lies in the high tunability of its physical parameters by adjusting the layer twist angle, electrical field, moiré carrier filling and interlayer coupling. An international team of researchers (USA – University of Washington, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, Hong Kong, Japan) found that optical excitation can highly tune the spin–spin interactions between moiré-trapped carriers, resulting in ferromagnetic order in WS2 /WSe2 moiré superlattices. Near the filling factor of −1/3, as the excitation power […]
Optimizing silicon structure to reduce reflection
Nanowerk April 14, 2022 Researchers in China examined changes in the porous structure of silicon to make it less reflective and thus a better material for solar absorbing technology. Currently, the reflectivity of porous silicon prepared using electrochemical methods is around 5 to 10 per cent, with the lowest reflectivity being 4.7 per cent for light in the wavelength range of 300 to 1000 nanometres. They calculated and compared the surface reflectivity of porous silicon structures with different pore sizes. They discovered that the porous silicon structure when prepared under the optimal corrosion parameters can achieve an average reflectivity as […]
Scientists bioprint tissue-like constructs capable of controlled, complex shape change
Phys.org March 31, 2022 The development of hydrogel-based 4D bioinks, especially those allowing living cell printing, with easy preparation, defined composition, and controlled physical properties is critically important for 4D bioprinting. Researchers at the University of Illinois have developed a single-component jammed micro-flake hydrogel (MFH) system with heterogeneous size distribution, which differs from the conventional granular microgel as a new cell-laden bioink for 4D bioprinting. The cytocompatible MFH features scalable production and straightforward composition with shear-thinning, shear-yielding, and rapid self-healing properties. It can be smoothly printed into stable 3D bioconstructs, which can be further cross-linked to form a gradient in […]
Engineering the quantum states in solids using light
Science Daily March 30, 2022 In previous experiments, the light intensity for realizing Floquet state (where the original quantum state is replicated when light is irradiated on matters) in solids was enormous due to the high frequency of light. An international team of researchers (South Korea, Japan) succeeded in the experimental realization of the steady Floquet state in a graphene Josephson junction (GJJ) by irradiating continuous microwaves on it. The intensity of the light was decreased to one trillionth the value of previous experiments, significantly reducing the heat generation and enabling continuously long-lasting Floquet states. They also developed a novel […]
Study shows how superconductivity can be switched on and off in superconductors
Phys.org March 30, 2022 Recent experiments have suggested that superconductivity in metallic nanowires can be suppressed by the application of modest gate voltages. The source of this gate action has been debated and either attributed to an electric-field effect or to small leakage currents. An international team of researchers (Switzerland, Italy, USA – IBM, NY) has shown that the suppression of superconductivity in titanium nitride nanowires on silicon substrates does not depend on the presence or absence of an electric field at the nanowire but requires a current of high-energy electrons. The suppression is most efficient when electrons are injected […]
Extracting mechanical work from superfast-expanding hydrogels
Nanowerk March 12, 2022 Superabsorbent polymer gels can absorb large amounts of water (100–1000× their dry weight). However, gels that are both superabsorbent and able to expand rapidly have not yet been realized. Researchers at the University of Maryland created such gels by in situ foaming of a monomer solution (acrylic acid and acrylamide) using a double-barreled syringe which has acid and base in its two barrels. The gas generated by the acid–base reaction, was stabilized by an amphiphilic polymer in one of the barrels. The monomers are then polymerized by UV light to form the gel around the bubbles, […]
Quantum information: Light from rare-earth molecules
Nanowerk March 11, 2022 Rare-earth ions (REIs) are promising solid-state systems for building light–matter interfaces at the quantum level. However, few crystalline materials have shown an environment quiet enough to fully exploit REI properties. Molecular systems can provide such capability but generally lack spin states and they show broad optical lines that severely limit optical-to-spin coherent interfacing. An international team of researchers (France, Germany) found that europium molecular crystals exhibit linewidths in the tens of kilohertz range, orders of magnitude narrower than those of other molecular systems. They harnessed this property to demonstrate efficient optical spin initialization, coherent storage of […]