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 […]
Category Archives: Advanced materials
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 […]
An intelligent soft material that curls under pressure or expands when stretched
Nanowerk February 24, 2021 Existing perceptive soft actuators require complex integration and coupling between the discrete functional units to achieve autonomy and intelligently interact with humans and the environment. Researchers in China have developed actuators with embodied sensing, actuation, and control at the single-unit level by synergistically harnessing the mechanosensing and electrothermal properties of liquid metal (LM) to actuate the thermally responsive liquid crystal elastomer (LCE). They created multifunctional LM circuits on the LCE surface using a simple and facile methodology based on magnetic printing. The fluidic LM circuit can be utilized as a conformable resistive heater, and a sensory […]
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 […]
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 […]
‘Magnetic graphene’ forms a new kind of magnetism
EurekAlert February 8, 2021 An international team of researchers ( UK, Uzbekistan, Russia, France, USA – Oak Ridge National Laboratory, Vietnam, South Korea, Czech Republic) was able to control the conductivity and magnetism of iron thiophosphate (FePS3) which undergoes a transition from an insulator to a metal when compressed. Using new techniques to measure the magnetic structure up to record-breaking high pressures, they found that magnetism survives, but gets modified into new forms, giving rise to new quantum properties in a new type of magnetic metal. The ‘spin’ of the electrons has been shown to be the source of magnetism. […]
An optical coating like no other
Nanowerk February 5, 2021 An international team of researchers (USA – University of Rochester, Case western University, Italy) applied a 15 nanometer-thick film of germanium to a metal surface resulting in a surface capable absorbing a broad band of wavelengths. Combining it with a cavity that supports a narrowband resonance resulted in coupled cavities that exhibit Fano resonance that can reflect a very narrow band of light. The semi-transparent Fano resonance optical coationgs (FROCs) can transmit and reflect the same colour as a beam splitter filter. FROCs can spectrally and spatially separate the thermal and photovoltaic bands of the solar spectrum, […]
Scientists create armor for fragile quantum technology
Phys.org February 8, 2021 Integration of TMDCs into practical all‐dielectric heterostructures hinges on the ability to passivate and protect them against necessary fabrication steps on large scales. An international team of researchers (Australia, Germany) has created the protective layer by exposing a droplet of liquid gallium to air, which immediately formed a perfectly even three nanometers thick layer of gallium oxide on its surface. By squashing the droplet on top of the 2D material with a glass slide, the gallium oxide layer can be transferred from the liquid gallium onto the material’s entire surface, up to centimetres in scale. Because […]