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CaSrxCu3−xTi4O12 Ceramic Oxide Modified with Graphene Oxide and Reduced Graphene Oxide for Supercapacitor Applications

This study investigates CaCu3−xSrxTi4O12 (CCSTO) systems synthesized using the solid-state method, with x compositions of 0.00, 0.15, and 3.00. The samples were modified using 6 wt% graphene oxide (GO) and reduced GO (rGO) prepared via Hummer’s method to evaluate their performance as electrodes in supercapacitors. The results indicate that the addition of 6wt% rGO to CCTO (CCTO-6rGO) led to an improvement in specific capacitance, reaching 237.76 mF·g−1 at a scan rate of 10 mV/s, compared to 29.86 mF·g−1 for pure CCTO and only 7.83 mF·g−1 for CCTO-6GO, suggesting that rGO enhances charge storage. For the CCTO15Sr samples, CCTO15Sr-6rGO exhibited the highest specific capacitance, with 321.63 mF·g−1 at 10 mV/s, surpassing both pure CCTO15Sr (80.19 mF·g−1) and CCTO15Sr-6GO (25.73 mF·g−1). These results stem from oxygen and metal vacancies, which aid charge accumulation and ion diffusion.

Scientists get a first look at the innermost region of a white dwarf system

Some 200 light years from Earth, the core of a dead star is circling a larger star in a macabre cosmic dance. The dead star is a type of white dwarf that exerts a powerful magnetic field as it pulls material from the larger star into a swirling, accreting disk. The spiraling pair is what’s known as an “intermediate polar” — a type of star system that gives off a complex pattern of intense radiation, including X-rays, as gas from the larger star falls onto the other one.

Now, MIT astronomers have used an X-ray telescope in space to identify key features in the system’s innermost region — an extremely energetic environment that has been inaccessible to most telescopes until now. In an open-access study published in the Astrophysical Journal, the team reports using NASA’s Imaging X-ray Polarimetry Explorer (IXPE) to observe the intermediate polar, known as EX Hydrae.

The team found a surprisingly high degree of X-ray polarization, which describes the direction of an X-ray wave’s electric field, as well as an unexpected direction of polarization in the X-rays coming from EX Hydrae. From these measurements, the researchers traced the X-rays back to their source in the system’s innermost region, close to the surface of the white dwarf.

Single-photon switch could enable photonic computing

There are few technologies more fundamental to modern life than the ability to control light with precision. From fiber-optic communications to quantum sensors, the manipulation of photons underpins much of our digital infrastructure. Yet one capability has remained frustratingly out of reach: controlling light with light itself at the most fundamental level using single photons to switch or modulate powerful optical beams.

Now, researchers at Purdue University have achieved this long-sought milestone, demonstrating what they call a “photonic transistor” that operates at single-photon intensities.

Their findings, published in the journal Nature Nanotechnology, report a nonlinear refractive index several orders of magnitude higher than the best-known materials, a leap that could finally make photonic computing practical.

Potentially distinct structure in Kuiper belt discovered with help of clustering algorithm

A vast region of our solar system, called the Kuiper belt, stretches from the orbit of Neptune out to 50 or so astronomical units (AU), where an AU is the distance between Earth and the sun. This region consists mostly of icy objects and small rocky bodies, like Pluto. Scientists believe Kuiper belt objects (KPOs) are remnants left over from the formation of the solar system.

Now, a new preprint paper on arXiv describes a newly identified region that appears to be completely distinct from other parts of the Kuiper belt—but some uncertainty remains.

Final experimental result for the muon still challenges theorists

For experimental physicists, the latest measurement of the muon is the best of times. For theorists there’s still work to do.

Colliding 300 billion muons over four years at the Fermi National Accelerator Laboratory in the U.S., the Muon g-2 Collaboration —a group of over 200 researchers—has measured the magnetic strength of the muon to unprecedented precision: accurate to 127 parts per billion.

These final results on the muon’s magnetic moment—measured by its frequency of the moment’s wobbling in an external magnetic field—are the end of a chain of experimental efforts going back 30 years and have been published in the journal Physical Review Letters.

Laser-induced break-up of C₆₀ fullerenes caught in real-time on X-ray camera

The understanding of complex many-body dynamics in laser-driven polyatomic molecules is crucial for any attempt to steer chemical reactions by means of intense light fields. Ultrashort and intense X-ray pulses from accelerator-based free electron lasers (FELs) now open the door to directly watch the strong reshaping of molecules by laser fields.

A prototype molecule, the famous football-shaped “Buckminsterfullerene” C₆₀, was studied both experimentally and theoretically by physicists from two Max Planck Institutes, the one for Nuclear Physics (MPIK) in Heidelberg and the one for the Physics of Complex Systems (MPI-PKS) in Dresden in collaboration with groups from the Max Born Institute (MBI) in Berlin and other institutions from Switzerland, U.S. and Japan.

For the first time, the experiment carried out at the Linac Coherent Light Source (LCLS) of the SLAC National Accelerator Laboratory could image strong-laser-driven molecular dynamics in C₆₀ directly.

Atoms passing through walls: Quantum tunneling of hydrogen within palladium crystal

At low temperatures, hydrogen atoms move less like particles and more like waves. This characteristic enables quantum tunneling, the passage of an atom through a barrier with a higher potential energy than the energy of the atom. Understanding how hydrogen atoms move through potential barriers has important industrial applications. However, the small size of hydrogen atoms makes direct observation of their motion extremely challenging.

In a study published in Science Advances, researchers at the Institute of Industrial Science, The University of Tokyo report precise detection of quantum tunneling of hydrogen atoms in palladium metal.

Palladium is a metal that absorbs hydrogen. Palladium atoms are arranged in a repeating three-dimensional cubic pattern, otherwise known as a lattice. Hydrogen atoms can enter this lattice by occupying interstitial sites between the large palladium atoms. These sites are octahedral and tetrahedral in shape. Hydrogen sits stably in an octahedral site and can hop to another octahedral site via a tetrahedral site, which is metastable, i.e., less stable than an octahedral site.

Mirror symmetry prompts ultralow magnetic damping in 2D van der Waals ferromagnets

Two-dimensional (2D) van der Waals (vdW) ferromagnets are thin and magnetic materials in which molecules or layers are held together by weak attractive forces known as vdW forces. These materials have proved to be promising for the development of spintronic devices, systems that operate leveraging the spin (i.e., intrinsic angular momentum) of electrons, as opposed to electric charge.

A crucial parameter in the context of magnetization is the so-called Gilbert damping coefficient, which indicates how quickly a material’s magnetization loses energy and returns to a state of equilibrium after being disturbed. A lower damping coefficient is more favorable for the development of spintronics, as it means that less energy is lost once a material’s magnetization is set into motion.

Researchers at Beijing Normal University, Shanghai University and Fudan University carried out a study aimed at better understanding the underpinnings of low Gilbert damping in 2D vdW ferromagnets.

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