Science Daily September 21, 2023 One of the hallmarks of Magnetic Weyl semimetals (mWSMs) is the emergence of large intrinsic anomalous Hall effect. On heating the mWSM above its Curie temperature, the magnetism vanishes while exchange-split Weyl point pairs collapse into doubly degenerate gapped Dirac states. Researchers in Japan found potential of these Dirac nodes in paramagnetic state for efficient spin current generation at room temperature via the spin Hall effect. They introduced Ni and In to separately substitute Co and Sn in a prototypal mWSMCo3Sn2S2 shandite film and tuned the Fermi level. Composition dependence of spin Hall conductivity for […]
Tag Archives: S&T Japan
Copper-doped tungstic acid nanocrystals transform infrared light conversion
Nanowerk September 13, 2023 The technology to utilize the full spectrum of solar radiation is still in its infancy as conventional methods constrain their all-solar response. Researchers in Japan have proposed using – submerged photosynthesis of crystallites (SPsC). They showed that strategic doping with copper and oxygen vacancies can induce opto-critical phases from the non-stoichiometric tungstic acids. These opto-critical phases enabled a dynamic equilibrium shift in lattice defect stabilization, facilitating an unprecedented whole solar wavelength response. The response manifested photo-assisted water evaporation, and photo-electrochemical characteristics. According to the researchers their strategy of harnessing all-solar energy, the one-pot SPsC strategy, may […]
A new design strategy for mechanoresponsive materials with high thermal tolerance
Phys.org September 11, 2023 Radical type mechanophores (RMs), molecules that can undergo small-scale chemical reactions upon exposure to a mechanical stimulus are studied due to their potential application in the fabrication of highly functionalized polymers. However, the lack of a rational design concept with pre-determined properties limits their development. Researchers in Japan have developed a rational design strategy of RMs with high thermal tolerance while maintaining mechanoresponsiveness. Through experimental and theoretical analysis, they found that the high thermal tolerance of RMs is related to the radical-stabilization energy (RSE) as well as the Hammett and modified Swain–Lupton constants at the para-position. […]
‘Countercation engineering’ for thermoresponsive graphene-oxide nanosheets
Phys.org August 31, 2023 Thermoresponsive graphene-oxide (GO) nanosheets have been widely employed to develop smart membranes/surfaces, hydrogel actuators, recyclable systems, and biomedical applications. Current synthetic strategies to generate thermoresponsive GO nanosheets have exclusively relied on the covalent or non-covalent modification of their surfaces with thermoresponsive polymers. Researchers in Japan discovered that GO nanosheets with Bu4N+ countercations became thermoresponsive in water without the use of any thermoresponsive polymers, inducing a reversible sol–gel transition via their self-assembly and disassembly processes. The resultant dispersion can be used as a direct writing ink for constructing a three-dimensionally designable gel architecture of the GO nanosheets. […]
Novel titanium dioxide catalyst shows promise for electrocatalytic carbon dioxide reduction
Phys.org September 5, 2023 CO2 can be selectively reduced by gold, lead, etc. supported on conductive carbon. However, the high pH in the vicinity of the electrode raises concerns about the catalyst and catalyst support degradation. Researchers in Japan used chemically stable titanium dioxide (TiO2) powder as an alternative to carbon. TiO2 maintained its particle shape and crystalline structure after in-liquid plasma treatment was used to improve its electrochemical properties. When its electrochemical properties were evaluated, they observed the disappearance of Ti4+ and Ti3+ redox peaks derived from TiO2 and a decrease in hydrogen overvoltage. The hydrogen overvoltage relationship suggested […]
A novel laser slicing technique for diamond semiconductors
Nanowerk August 1, 2023 Laser slicing is a technique of slicing materials along cracks formed by scanning a focused ultrashort-pulse laser beam inside the materials. Researchers in Japan proposed a novel slicing technique to fabricate diamond wafers and demonstrate slicing at the {100} surface. Cracks parallel to the {100} plane are needed to fabricate the wafer. However, crystal materials contain a cleavage plane at the {111} plane, which cracks easily. Typically, cracks propagate not only along the {100} plane, which was the intended slicing plane, but also along the {111} plane, which increased the kerf loss. To restrict these undesirable […]
Insights into designing advanced stimuli-responsive porous materials
Phys.org July 21, 2023 MOFs which possess a high degree of crystallinity and a large surface area with tunable inorganic nodes and organic linkers. The adsorption in MOFs changes the crystalline structure and elastic moduli. Thus, the coexistence of adsorbed/desorbed sites makes the host matrices elastically heterogeneous. To show the asymmetric role of elastic heterogeneity in the adsorption–desorption transition researchers in Japan constructed a minimal model incorporating adsorption-induced lattice expansion/contraction and an increase/decrease in the elastic moduli. They found that the transition was hindered by the entropic and energetic effects which become asymmetric in the adsorption process and desorption process, […]
Novel thermal sensor could help drive down the heat
Science Daily July 24, 2023 Excess heat from electronic or mechanical devices is a sign or cause of inefficient performance. In many cases, embedded sensors to monitor the flow of heat could help engineers alter electronic or mechanical devices behavior or designs to improve their efficiency. Researchers in Japan explored the way a heat flux sensor consisting of certain special magnetic materials and electrodes behaves when there are complex patterns of heat flow. They etched desired patterns into the resultant film, similar to how electronic circuits are made. They designed the circuits in a particular kind of way to boost […]
Researchers use liquid crystals that mimic beetle shell coloration units to create a more secure type of QR code
Phys.org July 14, 2023 Cholesteric liquid crystals (CLCs) are becoming increasingly popular due to their unique chiral structural color. Unlike ordinary CLCs materials, CLCs particles exhibit angle-independence, making them particularly noteworthy. However, currently, there are limited effective methods for controlling the structural color of CLCs particles, other than adjusting the concentration of chiral dopants or introducing stimuli-responsive groups. Researchers in Japan have developed a scalable and cost-effective process for preparing monodisperse CLCs particles via dispersion polymerization. By making CLCs into micrometer-sized monodisperse spheres, the helical pitch of CLCs could be varied according to its particle size, and the resulting structural […]
New material shows promise for next-generation memory technology
Nanowerk July 10, 2023 Phase change memory could potentially revolutionize data storage because of its high storage density, and faster read and write capabilities. But still, the complex switching mechanism and intricate fabrication methods associated with these materials have posed challenges for mass production. Unlike conventional amorphous-crystalline PCMs, NbTe4 demonstrates both a low melting point and a high crystallization temperature. This unique combination offers reduced reset energies and improved thermal stability at the amorphous phase. Researchers in Japan fabricated NbTe4 and evaluated its switching performance. It exhibited a significant reduction in operation energy compared to conventional phase-change memory compounds. The […]