Science Daily March 22, 2021 Biological molecules in living organisms have a remarkable ability to form self-assembled structures when triggered by an external molecule. Based on this concept researchers in Japan created a tunable system involving poly(sodium acrylate) microparticles that can have one of two types of chemical groups attached. The adjustable parameters x and y refer to the molar percent of microparticles with β-cyclodextrin and adamantyl residues, respectively. The shape of assemblies formed by microparticles was dependent on the residue content. For assemblies to form, x needed to be at least 22.3. As the value of y increased, the […]
Tag Archives: Materials science
Controlled by light alone, new smart materials twist, bend and move
Science Daily March 12, 2021 The ability to topographically control photonic bandgaps allows programmable actuation of the elastomeric substrate in response to illumination. An international team of researchers (USA – Tufts University, Northwestern University, Italy) combined programmable photonic function with elastomeric material composites to generate optomechanical actuators that display controllable and tunable actuation as well as complex deformation in response to simple light illumination. They developed complex three-dimensional configurations, programmable motion patterns, and phototropic movement where the material moves in response to the motion of a light source. A “photonic sunflower” demonstrator device consisting of a light-tracking solar cell was […]
Researchers make breakthrough in solar cell materials
Phys.org March 12, 2021 An international team of researchers (USA – Clemson University, Los Alamos National Laboratory, University of Alabama, China) observed the ultrafast dynamics of trapped carriers in organic methyl ammonium lead halide perovskite thin films by ultrafast photocurrent spectroscopy. Upon ultrafast laser excitation, trapped carriers followed a phonon assisted tunneling mechanism and a hopping transport mechanism along ultra-shallow to shallow trap states ranging from 1.72–11.51 millielectronvolts. They validated the transport mechanisms by highlighting trap state dynamics, including trapping rates, de-trapping rates and trap properties, such as trap density, trap levels, and capture-cross sections. The work establishes a foundation […]
Team creates new ultralightweight, crush-resistant tensegrity metamaterials
Phys.org March 11, 2021 Catastrophic collapse of materials and structures is the inevitable consequence of a chain reaction of locally confined damage. A-team of researchers in the US (UC Irvine, Georgia Institute of Technology) created mechanical metamaterials that delocalize deformations to prevent failure. They used direct laser writing technique to generate elementary cells sized between 10 and 20 microns which were built up into eight-unit supercells that could be assembled with others to make a continuous structure. They showed that failure resistance is up to 25‐fold enhancement in deformability and orders of magnitude increased energy absorption capability without failure over […]
Scientists have synthesized a new high-temperature superconductor
Phys.org March 10, 2021 An international team of researchers (Russia, USA – University of Chicago, Spain, Italy, China) performed theoretical and experimental research on yttrium hydride (YH6), one among the three highest-temperature superconductors known to date. All these hydrides reach their maximum superconductivity temperatures at very high pressures. The current challenge is to attain room-temperature superconductivity at lower pressures. In the case of YH6, the agreement between theory and experiment is rather poor. For example, the critical magnetic field observed in the experiment is 2 to 2.5 times greater as compared to theoretical predictions. This is the first-time scientists encounter such […]
Engineering the boundary between 2D and 3D materials
MIT News February 26, 2021 The atomic structure at the interface between 2D and 3D materials influences properties such as contact resistance, photo-response, and high-frequency electrical performance. An international team of researchers (USA – MIT, Harvard University, Canada) used epitaxially aligned MoS2/Au as a model system to demonstrate the use of advanced scanning transmission electron microscopy combined with a geometric convolution technique in imaging the crystallographic moiré pattern at the 2D/3D interface. This moiré period is often hidden in conventional electron microscopy, where the Au structure is seen in projection. They showed that charge density is modulated according to the […]
Magnetic effect without a magnet
Nanowerk February 22, 2021 An international team of researchers (Austria, Switzerland, Canada, USA – Rice University) found Ce3Bi4Pd3 produced a giant Hall effect in the total absence of any magnetic field and showed that the strange phenomenon is due to the complicated interaction of the electrons. Specific symmetries of the atoms determine the dispersion relation, the relationship between the energy of the electrons and their momentum. This complex interaction results in phenomena that mathematically look as if there are magnetic monopoles in the material which do not exist in this form in nature. But it has the effect of a […]
New phenomena for the design of future quantum devices
Nanowerk February 20, 2021 A team of researchers in the US (MIT, Pennsylvania State University, Argonne National Laboratory, Oak Ridge National Laboratory, NIST, University of Maryland) has shown that due to a new class of Kohn anomaly the topology of the electronic states in a topological material can leave fingerprints on their phonon properties. They experimentally observed it through inelastic x-ray and neutron scattering on WSM (Weyl semimetal) tantalum phosphide. Compared to the conventional Kohn anomaly, the Fermi surface in a WSM exhibits multiple topological singularities of Weyl nodes, leading to a distinct nesting condition with chiral selection, a power-law […]
Breakthrough material can protect satellites from ultraviolet radiation and atomic oxygen in low-Earth orbit
Phys.org February 16, 2021 Atomic oxygen is created when O2 molecules break apart, a process made easier in space because of the abundance of ultraviolet radiation affecting the structural integrity of space structures. An international team of researchers (UK, Germany) has developed a nano-barrier that bonds to the surface of polymer or composite materials, protecting them from erosion in low-Earth orbit without disrupting the functional performance of the space structure. The multilayered protection barrier deposited via a custom-built plasma-enhanced chemical vapor deposition system is designed to deposit all necessary layers without breaking vacuum to maximize the adhesion to the surface […]
Scientists manipulate magnets at the atomic scale
Science Daily February 12, 2021 An international team of researchers (the Netherlands, Ukraine, Russia, Belgium, UK) shows that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses tuned to resonance with a phonon mode of the archetypical antiferromagnet DyFeO3 induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. Non-thermal lattice control of the magnetic exchange, which defines the stability of the macroscopic magnetic state, allows picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders. The discovery emphasizes the potential of resonant phonon excitation […]