Phys.org December 13, 2024 Thermoplastic elastomers (TPEs) are nanostructured, melt-processable, elastomeric block copolymers. When TPEs that form cylindrical or lamellar nanostructures are macroscopically oriented, their material properties can exhibit several orders of magnitude of anisotropy. Researchers at Princeton University demonstrated that the flows applied during the 3D printing of a cylinder-forming TPE enables hierarchical control over material nanostructure and function. 3D printing allowed control over the extent of nanostructural and mechanical anisotropy. They had tunable local and macroscopic mechanical responses. They achieved melt-reprocessability over multiple cycles, reprogramability, and robust self-healing via a brief period of thermal annealing, enabling facile fabrication […]
Tag Archives: Materials science
Scientists reveal superconductivity secrets of an iron-based material
Phys.org December 5, 2024 Although this high Tc is thought to be associated with electron–phonon coupling (EPC), the microscopic coupling mechanism and its role in the superconductivity remain elusive. An international team of researchers (USA – UC Irvine, Princeton University, China, Sweden) atomically resolved the phonons at the FeSe/STO interface and uncovered new optical phonon modes, coupling strongly with electrons, in the energy range of 75–99 meV. These modes were characterized by out-of-plane vibrations of oxygen atoms in the interfacial double-TiOx layer and the apical oxygens in STO. Their results demonstrated that the EPC strength and superconducting gap of 1 uc FeSe/STO […]
Straining a material’s atomic arrangement may make for cleaner, smarter devices
Phys.org December 5, 2024 Strong coupling between polarization (P) and strain (ɛ) in ferroelectric complex oxides offers unique opportunities to dramatically tune their properties. An international team of researchers (USA – Pennsylvania State University, Cornell University, Stanford University, University of Nebraska, Argonne National Laboratory, Belgium, Germany) demonstrated strain tuning of ferroelectricity in epitaxial potassium niobate (KNbO3) thin films grown by sub-oxide molecular beam epitaxy. While bulk KNbO3 exhibited three ferroelectric transitions and a Curie temperature (Tc) of ≈676 K, phase-field modeling predicted that a biaxial strain pushes its Tc > 975 K, its decomposition temperature in air, and for −1.4% […]
Enormous cache of rare earth elements hidden inside coal ash waste, study suggests
Phys.org November 19, 2024 The renewable energy industry is heavily reliant on rare earth elements. A team of researchers in the US (UT Austin, University of Kentucky, University of Wyoming, industry) estimated coal ash resources and potential for extraction of rare earth elements using data for the US. According to the data ~ 52 gigatons (Gt) of coal was produced in the US (1950–2021). Power plants account for most of the coal use. About 70% of coal ash was potentially accessible for rare earth element extraction (1985–2021) and was disposed in landfills and ponds with the remaining coal ash was used […]
How can electrons split into fractions of themselves?
MIT News November 18, 2024 Recent experiments on the moiré structure formed by pentalayer rhombohedral graphene aligned with a hexagonal boron nitride substrate report the discovery of a zero-field fractional quantum Hall effect. These “(fractional) quantum anomalous Hall” [(F)QAH] phases occur for one sign of a perpendicular displacement field, and correspond, experimentally, to full or partial filling of a valley polarized Chern-1 band. Such a band is absent in the noninteracting band structure. Researchers at MIT showed that electron-electron interactions play a crucial role, and presented microscopic theoretical calculations demonstrating the emergence of a nearly flat, isolated, Chern-1 band and […]
Physicists reveal how layers and twists impact graphene’s optical conductivity
Phys.org November , 2024 An international team of researchers (USA – Florida State University, China) explored the advantages of moiré superlattices in twisted bilayer graphene (TBG) aligned with hexagonal boron nitride (hBN) for passively enhancing optical conductivity in the low-energy regime. To probe the local optical response of TBG/hBN double-moiré lattices, they used infrared nano-imaging in conjunction with nanocurrent imaging to examine local optical conductivity over a wide range of TBG twist angles. They showed that interband transitions associated with the multiple moiré flat and dispersive bands produced tunable transparent IR responses even at finite carrier densities, which is in […]
Engineered bacterial protein offers efficient rare earth metal separation
Phys.org October 28, 2024 Elucidating details of biology’s selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for many modern technologies. Researchers at The Pennsylvania State University biochemically and structurally characterized Methylobacterium (Methylorubrum) extorquens LanD from a bacterial gene cluster for lanthanide uptake. The protein provided only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favored the largest lanthanide, LaIII. Selective dimerization enriched high-value PrIII and NdIII relative to low-value LaIII and CeIII in an all-aqueous process, achieved higher separation factors […]
New method successfully recycles carbon fiber composite into reusable materials
Phys.org October 31, 2024 Carbon fiber reinforced polymers (CFRPs, or composites) are increasingly replacing traditional manufacturing materials used in the automobile, aerospace, and energy sectors. With this shift, a team of researchers in the US (University of Southern California, University of Kansas) developed an end-of-life processes for CFRPs and demonstrated a strategy to upcycle pre- and postconsumer polystyrene-containing CFRPs, cross-linked with unsaturated polyesters or vinyl esters, to benzoic acid. The thermoset matrix was upgraded via biocatalysis utilizing an engineered strain of the filamentous fungus Aspergillus nidulans, which gave access to valuable secondary metabolites in high yields. Reactions were engineered to […]
Graphene-based memristors move a step closer to benefiting next-generation computing
Phys.org October 22, 2024 Memristors based on graphene is a promising alternative to contemporary field-effect transistor (FET) technology achieves higher integration density and lower power consumption. The use of graphene as electrodes in memristors could also increase robustness against degradation mechanisms. To realize this researchers in the UK have developed a process for direct growth of high-quality monolayer graphene on sapphire wafers in a mass-producible, contamination-free, and transfer-free manner using a commercially available metal–organic chemical vapor deposition (MOCVD) system. Using their process they developed graphene-electrode based memristors incorporating graphene electrodes at wafer scale. The memristor demonstrated promising characteristics in terms […]
Superconductivity offers new insights into quantum material MnBiâ‚‚Teâ‚„
Phys.org October 23, 2024 Topological superconductors hosting Majorana zero modes are of great interest for both fundamental physics and potential quantum computing applications. Researchers in the Netherlands investigated the transport properties of the intrinsic magnetic topological insulator MnBi2Te4 (MBT). They found that the presence of chiral edge channels, though with deviations from perfect quantization due to factors such as non-uniform thickness, domain structures, and the presence of quasi-helical edge states. The fabricated superconducting junctions using niobium led on MBT exfoliated flakes, which showed an onset of supercurrent with clear Josephson coupling. The interference patterns in the superconducting junctions revealed interesting […]