Nanowerk September 7, 2021 An international team of researchers (USA – MIT, Japan) has demonstrated that when two single sheets of boron nitride are stacked parallel to each other, at room temperature, the material becomes ferroelectric, in which positive and negative charges in the material spontaneously head to different sides, or poles. Upon the application of an external electric field, those charges switch sides, reversing the polarization. Twisting the boron nitride sheets by a small angle changes the dynamics of switching because of the formation of moiré ferroelectricity with staggered polarization. The coupling between vertical polarization and horizontal motion is […]
Tag Archives: Materials science
Discovery of two-phase superconductivity in CeRh2As2
Science Daily August 26, 2021 Although tens of unconventional superconductors have been discovered in the past half century, there was good thermodynamic evidence of more than one superconducting phase in only one or two materials. An international team of researchers (Germany, New Zealand, UK) used thermodynamic probes to establish two-phase superconductivity in CeRh2As2. Both materials have the highest critical magnetic field to superconducting transition temperature ratio of any known superconductor. The findings can be expected to generate entirely new research directions…read more. TECHNICAL ARTICLE
Light-induced shape shifting of MXenes
Phys.org September 1, 2021 MXenes are two-dimensional sheets of transition metal carbides or nitrides in the form of few-atom-thick single layers. An international team of researchers (Germany, Switzerland) has found a new way to enhance the properties of MXenes by shining fast light pulses on them. Using ultrafast electron microscopy with atomic spatial resolution they showed that the laser energy transfers to the atomic lattice in a record-breaking time of merely 230 femtoseconds. They also found that femtosecond laser light can be used to switch back and forth between the originally flat surface structure of the MXene and a nano-wave […]
New approach creates an exceptional single-atom catalyst for water splitting
Phys.org September 1, 2021 Electrolysis could produce fuels and chemical feedstocks more sustainably and reduce the use of fossil fuels. But the sluggish pace of oxygen evolution reaction (OER) has been a bottleneck to improving its efficiency. A team of researchers in the US (Stanford University SLAC National Accelerator Laboratory, Lawrence Berkeley National Laboratory, UC Berkeley, NIST) used operando X-ray absorption spectroscopy measurements to demonstrate that the origin of water oxidation activity of IrNiFe SACs is the presence of highly oxidized Ir single atom in the NiFe oxyhydroxide under operating conditions. They showed that the optimal water oxidation catalyst could […]
New family of ferroelectric materials raises possibilities for improved information and energy storage
Phys.org August 31, 2021 Researchers at Pennsylvania State University used magnesium-substituted zinc oxide thin films to make tiny capacitors. They could set their polarization orientation so that their surface charge is either plus or minus. The setting is nonvolatile. This type of storage requires no additional energy. The magnesium-substituted zinc oxide thin films can be deposited at much lower temperatures than other ferroelectric materials. Substrate temperature can be lowered to ambient conditions, and when doing so, capacitor stacks show only minor sacrifices to crystal orientation and nearly identical remanent polarization values; however, coercive fields drop below 2 MV/cm. This ability could […]
Dual-phase alloy extremely resistant to fractures
Phys.org August 20, 2021 An international team of researchers (China, USA – Argonne National Laboratory, University of Tennessee, Germany) has developed a new type of multi-principal element alloys (MPEA) called DS: EHEA (Directly Solidified: Eutectic High-Entropy Alloy) that features multiscale spatial heterogeneities using eutectic high-entropy alloys. They found that a particular aluminum-iron-cobalt-nickel dual-phase alloy solidified in a herringbone micropattern that was very highly resistant to fracturing. Its secret, they discovered, was in its hard and soft phases and the way cracks formed. Those that formed during the hard phase were stopped when they reached a border with a soft phase—the […]
Energy harvesting technology based on ferromagnetic resonance
Phys.org August 24, 2021 Researchers in Japan demonstrated electrical charging using the electromotive force (EMF) generated in a ferromagnetic metal (FM) film under ferromagnetic resonance (FMR). In the case of Ni80Fe20 films, electrical charge due to the EMF generated under FMR can be accumulated in a capacitor; however, the amount of charge is saturated well below the charging limit of the capacitor. In the case of Co50Fe50, electrical charge generated under FMR can be accumulated in a capacitor and the amount of charge increases linearly with the FMR duration time. The difference between the Ni80Fe20 and Co50Fe50 films is due […]
New insulation material provides more efficient electricity distribution
Phys.org August 26, 2021 One way to reduce transmission loses such as this is by increasing the direct current voltage level. However, an increase in the transmission voltage adversely affects the insulation of an HVDC cable. An international team of researchers (Sweden, Italy) have shown that by adding very small amounts of the conjugated poly(3-hexylthiophene) (P3HT), it is possible to lower the electrical conductivity by up to three times. The work opens new possibilities for manufacturers. The researchers believe that their discovery could lead to numerous new applications and directions for research…read more. Open Access TECHNICAL ARTICLE
Metamaterials research challenges fundamental limits in photonics
Phys.org August 10, 2021 Previous research was limited to modifying either absorption or refraction in metamaterials. Researchers at Cornell University have demonstrated that if both properties are modulated in time, it is possible to absorb electromagnetic waves much more efficiently than in a static structure, or in a structure in which either one of these two degrees of freedom is modulated individually. They combined these two aspects together to create a much more effective system. The findings may lead to the development of new metamaterials with wave absorption and scattering properties that far outperform what is currently available. The research […]
New electronic phenomenon discovered
Science Daily August 11, 2021 A team of researchers in the US (University of North Florida, University of Illinois, Arizona State University) has demonstrated a new electronic phenomenon they call “asymmetric ferroelectricity” in atomic layer superlattices constructed using three constituent phases, CaTiO3, SrTiO3 and BaTiO3. The stacking sequence of the atomic layers is found to control the symmetry of the high-temperature dielectric response. When a nanostructured asymmetric strain is programmed into the lattice via the stacking order, the natural symmetry at high temperatures is removed and a polarized sample is obtained in which the polarization increases as the temperature is […]