Science Daily May 25, 2021 Researchers in Switzerland have shown the nature of the structural disorder in bottom-up zigzag graphene nanoribbons along with its effect on the magnetism and electronic transport based on scanning probe microscopies and first-principles calculations. They found that edge-missing m-xylene units emerging during the cyclodehydrogenation step of the on-surface synthesis are the most common point defects. These “bite” defects act as spin-1 paramagnetic centers, severely disrupting the conductance spectrum around the band extrema, and give rise to spin-polarized charge transport. They also showed that the electronic conductance across graphene nanoribbons is more sensitive to “bite” defects […]
Tag Archives: Materials science
Harvesting light like nature does
Nanowerk May 15, 2021 Inspired by the formation of hierarchically structured natural biominerals (e.g., bone and tooth), various sequence-defined polymers have been synthesized and exploited for design and synthesis of functional hybrid materials. A team of researchers in the US (Pacific Northwest National Laboratory, Washington State University) created an altered protein-like structure, called a peptoid, and attached a precise silicate-based cage-like structure to one end of it. They found that, under the right conditions, they could induce these molecules to self-assemble into perfectly shaped crystals of 2D nanosheets. It has the programmability of a protein-like synthetic molecule with the complexity […]
Harnessing the hum of fluorescent lights for more efficient computing
Science Daily May 12, 2021 Magnetostriction, which causes the buzz of fluorescent lights and electrical transformers, occurs when a change in the shape of the material causes a change in magnetic field. An international team of researchers (USA – University of Michigan, Cornell University, SUNY Buffalo, UC Berkeley, University of Wisconsin, Purdue University, Germany) has developed a material made of a combination of iron and gallium which has at least twice as magnetostrictive and far less costly than other materials in its class. By freezing the iron-gallium alloy and preventing it from forming an ordered structure they were able to […]
Nanoscale defects could boost energy storage materials
Phys.org May 11, 2021 A team of researchers in the US (Cornell University, Virginia Tech, Argonne National Laboratory) synthesized a garnet crystal structure, lithium lanthanum zirconium oxide (LLZO), with various concentrations adding aluminum as a dopant. Through Bragg Coherent Diffractive Imaging they found the material’s morphology and atomic displacements. The researchers now plan to conduct a study that measures how the defects impact the performance of solid-state electrolytes in an actual battery. The study opens the possibility to design defects to make better energy storage materials…read more. TECHNICAL ARTICLE
Successful synthesis of perovskite visible-light-absorbing semiconductor material
Nanowerk May 7, 2021 Tin-containing oxide semiconductors are cheaper than most semiconductor materials, but their photofunctional applications are constrained by a wide optical band gap. Researchers in Japan doped hydride ions into the tin-containing semiconductor material successfully reducing the band gap from 4 eV to 2 eV, due to the chemical reduction of the tin component that accompanied the hydride ion doping. They verified tin reduction reaction in the semiconductor material through physicochemical measurements. The reduction leads to the generation of a “tin lone electron pair,” whose different electronic states notably contribute to the visible light absorption of the material. […]
A material keyboard made of graphene
Phys.org May 5, 2021 An international team of researchers (Switzerland, Japan) put two layers graphene flakes on top of each other and made a magic angle of exactly 1.06 degrees. The atomic crystal lattices of the graphene flakes created a moiré pattern. They attached several additional electrodes on top of the magic angle graphene flakes to apply an electric voltage to the material. By applying different voltages to the individual electrodes, they turned the magic angle graphene into an insulator in one spot, but a few hundred nanometres to one side it becomes a superconductor. For possible uses in quantum […]
Superconductivity, high critical temperature found in 2D semimetal tungsten nitride
Phys.org May 5, 2021 Researchers in Switzerland used first-principles calculations to identify intrinsic superconductivity in monolayer W2N3, a material that has recently been identified as being easily exfoliable from a layered hexagonal-W2N3 bulk by calculations, a theory also supported by experimental evidence. They found a critical temperature of 21 K, that is, just above liquid hydrogen and a record-high transition temperature for a conventional phonon-mediated 2D superconductor. According to the researchers the material could be doped such that currently unoccupied helical edge states 0.5 eV above the Fermi level become filled, even while superconductivity persists making W2N3 a viable candidate […]
Nature provides inspiration for breakthrough in self-regulating materials
Phys.org April 27, 2021 To make a series of oscillators to work in unison with each other, a team of researchers (UMass Amherst, Boston University, Harvard University, University of Colorado) has developed a versatile platform of light-driven active particles with interaction geometries that can be reconfigured on demand, enabling the construction of oscillator and spinner networks. The platform relies on the Marangoni effect, which is a phenomenon that describes the movement of solids along the interface between two fluids driven by changes in surface tension. They used hydrogel nanocomposite disks made up of polymer gels and nanoparticles of gold, which […]
New 2D superconductor forms at higher temperatures than ever before
Phys.org April 27, 2021 The distinctive electronic structure found at interfaces between materials can allow unconventional quantum states to emerge. An international team of researchers (USA – Argonne National Laboratory, University of Illinois, China) has discovered superconductivity in electron gases formed at interfaces between (111)-oriented KTaO3 and insulating overlayers of either EuO or LaAlO3. The superconducting transition temperature, as high as 2.2 kelvin, is about one order of magnitude higher than that of the LaAlO3/SrTiO3 system. Similar electron gases at KTaO3 (001) interfaces remain normal down to 25 millikelvin. The critical field and current-voltage measurements indicated that the superconductivity is […]
New two-dimensional material
Science Daily April 27, 2021 An international team of researchers (USA – Carnegie Institution for Science, Howard University, University of Chicago, Argonne National Laboratory, Germany, France, Russia, Sweden, the Netherlands, China) used the laser-heated diamond anvil cell technique with pressures of up to 100 gigapascals, to synthesize a Dirac material beryllonitrene (BeN4). These are beryllium polynitrides, some of which conform to the monoclinic, others to the triclinic crystal system. The triclinic beryllium polynitrides exhibit an unusual characteristic when the pressure drops. They take on a crystal structure made up of layers. Each layer contains zigzag nitrogen chains connected by beryllium […]