Nanowerk April 22, 2023 Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. Researchers in South Korea proposed a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. They constructed metasurface with rotatable unit cells (UCs) that […]
Category Archives: Advanced materials
Researchers uncover kinky metal alloy that won’t crack at extreme temperatures at the atomic level
Phys.org April 22, 2024 Refractory alloys are very resistant to heat and wear but are not ductile or resistant to fracture. A team of researchers in the US (UC Berkeley, Lawrence Berkeley National Laboratory, UC Irvine, Pacific Northwest National Laboratory) examined the strength and fracture toughness of the Single-phase body-centered cubic (bcc) refractory alloy, NbTaTiHf, from 77 to 1473 kelvin. Whereas the glide and intersection of screw and mixed dislocations promoted strain hardening controlling uniform deformation, the coordinated slip of <111> edge dislocations with {110} and {112} glide planes prolonged nonuniform strain through formation of kink bands. These bands suppressed […]
New adhesive tape picks up and sticks down 2D materials as easily as child’s play
Science Daily February 9, 2024 The use of graphene and other 2D materials to create electronic and optoelectronic devices has been limited by the lack of effective large-area transfer processes. An international team of researchers (South Korea, Japan) has developed a method that uses functional tapes with adhesive forces controlled by ultraviolet light. The adhesion of the tape was optimized for the transfer of monolayer graphene, providing a yield of over 99%. Once detached from the growth substrate, the graphene/tape stack enables easy transfer of graphene to the desired target substrate. The method could be used to transfer other 2D […]
Newly developed material gulps down hydrogen, spits it out, protects fusion reactor walls
Phys.org December 14, 2023 An international team of researchers (USA, South Korea, France, Germany) investigated tantalum (Ta) coating deposited by cold spray technology on 316L stainless steel substrate as a potential plasma-facing material surface. High fluence low energy deuterium plasma irradiation experiments and subsequent thermal annealing cycles associated with thermal desorption spectrometry (TDS) demonstrated superior structural stability of the Ta coating. TDS experiments revealed the outgassing of deuterium (as measure of its retention) for cold spray Ta coatings to be three times higher than bulk Ta and two orders of magnitude greater than bulk polycrystalline W. X-ray photoelectron spectroscopy revealed […]
Novel liquid metal circuits for flexible, self-healing wearables
Nanowerk October 2, 2023 Present integrated stretchable electronics easily suffer from electrical deterioration and face challenges in forming robust multilayered soft-rigid hybrid configurations. Researchers in Singapore have developed a bilayer liquid-solid conductor (b-LSC) with amphiphilic properties that reliably interfaces with both rigid electronics and elastomeric substrates. The top liquid metal could self-solder its interface with rigid electronics at a resistance 30% lower than the traditional tin-soldered rigid interface. The bottom polar composite comprising liquid metal particles and polymers could not only reliably interface with elastomers but also help the b-LSC heal after breakage. The b-LSC fabrication could be scaled up […]
Researchers improve the performance of semiconductors using novel 2D metal
Phys.org August 18, 2023 Metal contacts to MoS2 field-effect transistors play a determinant role in the device electrical characteristics and need to be chosen carefully. However, they suffer from high contact resistance because of the Schottky barrier and the Fermi level pinning effects that occur at the contact/MoS2 interface. To overcome this issue an international team of researchers (the Netherlands, India) investigated 2D metallic TiSx (x ∼ 1.8) as top contacts for MoS2 FETs using atomic layer deposition for the synthesis of both the MoS2 channels as well as the TiSx contacts and assessed the electrical performance of the fabricated […]
New paint gives extra insulation, saving on energy, costs, and carbon emissions
Phys.org August 14. 2023 Space heating and cooling consume ~13% of global energy every year. To thermally isolate the space of concern and minimize the heat exchange with the outside environment has been recognized as one effective solution. Researchers at Stanford University developed a universal category of colorful low-emissivity paints to form bilayer coatings consisting of an infrared (IR)-reflective bottom layer and an IR-transparent top layer in colors. High mid-infrared reflectance (up to ~80%) was achieved, which is more than 10 times as conventional paints in the same colors, efficiently reducing both heat gain and loss from/to the outside environment. […]
Bacteria as blacksmiths – new method to assemble unconventional materials
Nanowerk July 27, 2023 When in equilibrium, thermal forces agitate molecules, which then diffuse, collide, and bind to form materials. However, the space of accessible structures in which micron-scale particles can be organized by thermal forces is limited, owing to the slow dynamics and metastable states. Active agents in a passive fluid generate forces and flows, forming a bath with active fluctuations. Two unanswered questions are whether those active agents can drive the assembly of passive components into unconventional states and which material properties they will exhibit. Researchers in Austria showed that passive, sticky beads immersed in a bath of […]
Can rainbows monitor the environment?
Nanowerk July 31, 2023 Surface enhanced Raman scattering (SERS) is becoming a highly topical technique for identifying and fingerprinting molecules. Crucial for SERS is the need for substrates with strong and reproducible enhancements of the Raman signal over large areas and with a low fabrication cost. An international team of researchers (UK, Germany, the Netherlands, Belgium) found that dense arrays of plasmonic nanohelices have excellent SERS properties. As an illustration, they presented two new ways to probe near-field enhancement generated with circular polarization at chiral metasurfaces, first using the Raman spectra of achiral molecules (crystal violet) and second using a […]
New textile unravels warmth-trapping secrets of polar bear fur
Science Daily April 10, 2023 There are evidence that polar-dwelling animals have evolved a different mechanism of thermoregulation by using optical polymer materials to achieve an on-body “greenhouse” effect. Researchers at UMass Amherst designed a bilayer textile to mimic these adaptations. They showed that two ultralightweight fabrics with complementary optical functions, a polypropylene visible-transparent insulator and a nylon visible-absorber–infrared-reflector coated with a conjugated polymer, performed the same putative function as polar bear hair and skin, respectively. While retaining familiar textile qualities, these layers suppressed dissipation of body heat and maximized radiative absorption of visible light. Under moderate illumination of 130 […]