Phys.org November 6, 2024 Aquatic environments host various living organisms with active molecular systems that realize photosynthesis. Researchers in Japan addressed the significant challenges in using polymer networks as active mediators for photoinduced water splitting. They incorporated various features offered by artificial chloroplasts polymer networks for stepwise synthesis and integration during the hierarchical construction. The constituent molecules were closely arranged to smoothly operate forward reactions by polymer networks. The quantum efficiency of photoinduced H2 generation in gel systems was higher than that of conventional solution systems. Additionally, a thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) network of microgels could be used to integrate catalytic […]
Tag Archives: S&T Japan
New trigger proposed for record-smashing 2022 Tonga eruption—unstudied data from seismic wave points to early signals
Phys.org November 4, 2024 Researchers in Japan analyzed seismometer data recorded in Fiji and Futuna located over 750 km away. They extracted Rayleigh waves and estimated their powers and source directions, assuming retrograde particle motions. They found a Rayleigh wave from the HTHH’s direction about 15 min before the eruption onset. The arrival time difference of the Rayleigh wave between the two stations was consistent with that of the M5.8 earthquake during the eruption located beneath the HTHH. Referring to other seismic signals and satellite images, they concluded that the Rayleigh wave was the most significant eruption precursor with no […]
Successful development of a perfect diamagnetic conducting polymer
Phys.org October 28, 2024 Researchers in Japan synthesized Fe-doped polyaniline (D-PANI) in which they observed diamagnetism at T < 24 K under a weak external magnetic field. D-PANI was air-stable and showed the Peierls transition, as its resistivity increased rapidly at low temperatures, behaving as an electromagnetic insulator. It showed high sensitivity to magnetic fields, with its diamagnetic character changing under a relatively low magnetic field at 4 K. Its resistivity remained almost constant at high temperatures, and the nearest neighbor electron hopping conduction. Polarons in D-PANI showed perfect diamagnetism at low temperatures. After purification, D-PANI contained C, N, O, […]
New machine learning model quickly and accurately predicts dielectric function
Phys.org October 25, 2024 Fast and accurate prediction of dielectric function facilitates the development of novel dielectric materials, an ingredient of many cutting-edge technologies such as 6G networks. Researchers in Japan introduced a versatile machine-learning scheme implemented in Git hub for predicting dipole moments of molecular liquids to study dielectric properties. They attributed the center of mass of Wannier functions (called Wannier centers), to each chemical bond and created neural network models. They applied liquid methanol and ethanol to demonstrate that their neural network models successfully predicted the dipole moment of various liquid configurations in close agreement with DFT calculations. […]
Amorphous nanosheets created using hard-to-synthesize metal oxides and oxyhydroxides
Phys.org October 21, 2024 Amorphous 2D nanosheets have unique properties that are distinct from crystalline 2D nanosheets. However, compared with the vast library of crystalline 2D nanosheets, amorphous 2D nanosheets lack an efficient synthetic approach. Researchers in Japan developed a strategy that yields a library of 10 distinct amorphous 2D metal oxides/oxyhydroxides using solid-state surfactant crystals. A key feature of this process was a stepwise reaction using solid surfactant. The solid-state surfactant crystals have metal ions arranged in the interlayer space, and hydrolysis of the metal ions leads to the formation of isolated clusters in the surfactant crystals via limited […]
Magnetic octupoles help overcome problems with antiferromagnets
Phys.org October 17, 2024 The insensitive magneto-electric responses of antiferromagnets (AFMs) make controlling them in domain-wall devices challenging. An international team of researchers (Japan, USA – UCLA) demonstrated a current-driven fast magnetic octupole domain-wall (MODW) motion in Mn3X. The magneto-optical Kerr observation showed that the Néel-like MODW of Mn3Ge could be accelerated up to 750 m s-1 with a current density of only 7.56 × 1010 A m-2 without external magnetic fields. The MODWs showed high mobility with a small critical current density. They theoretically extended the spin-torque phenomenology for domain-wall dynamics from collinear to noncollinear magnetic systems. According to the researchers […]
Towards better solar cells: Exploring an anomalous phenomenon of electricity generation
Phys.org October 22, 2024 The photovoltaic effect can occur without metal/semiconductor or semiconductor/semiconductor interfaces in materials with spontaneous electric polarization due to a lack of spatial inversion symmetry known as bulk photovoltaic (BPV) effect which facilitates photoelectric conversion. Researchers in Japan reported an experimental demonstration of the BPV effect in α-In2Se3 films along the out-of-plane direction by using graphite films as transparent electrodes. A short-circuit current was detected under white light irradiation, and the sign was inverted upon inverting the direction of electric polarization, thus suggesting its origin to be the shift current, distinct from the effect occurring at the […]
Scientists use light to visualize magnetic domains in quantum materials
Phys.org October 11, 2024 Researchers in Japan visualized antiferromagnetic domains in a representative quasi-one-dimensional antiferromagnet using nonreciprocal directional dichroism, which differentiated the optical absorption of a pair of antiferromagnetic domains. Opposite antiferromagnetic domains, each about submillimeter in size, were found to coexist in a single-crystal specimen, and the domain walls ran predominantly along the spin chains. They showed that the domain walls could be moved by an applied electric field through a magnetoelectric coupling, and the direction of the domain walls was maintained during the motion. They explained the domain wall anisotropy by the quasi-one-dimensional nature of the exchange interactions. […]
Scientists demonstrate advanced low-coherence BOCDR system using periodic pseudo-random modulation
Phys.org October 1, 2024 Brillouin optical correlation-domain reflectometry (BOCDR) is a technique for measuring the distribution of strain and temperature along an optical fiber. However, it faces a trade-off between spatial resolution and measurement range. Researchers in Japan proposed low-coherence BOCDR based on periodic pseudo-random modulation to address this issue and demonstrated its proof-of-concept operation. First, the dependence of the light source output spectrum on modulation parameters was investigated showing the potential to resolve the trade-off between spatial resolution and measurement range. They also demonstrated the capability of measuring strain distribution along optical fibers without a variable delay line under […]
Solid electrolyte composed of nanoparticles shows promise for all-solid-state batteries
Phys.org October 2, 2024 Halide solid electrolytes are promising for improving the electrochemical performance of all-solid-state batteries. However, the state-of-the-art sodium-ion-conducting halides are not as high in conductivity as expected and lack reduction stability. Researchers in Japan found oxychlorides in a ternary system NaCl–TaCl5–Ta2O5 have high conductivities, formabilities, and oxidation and reduction stabilities. They mechanochemically prepared samples composed of NaCl and Ta2O5 nanoparticles embedded in an Na–Ta–Cl–O amorphous matrix, possessing ionic conductivities of 2.5 × 10–3 S cm–1 at 25 °C and electrochemical potential windows of 0.4–4.1 versus Na+/Na. Compression tests revealed that the nanoparticles in the oxychloride electrolytes improved […]