Phys.org February 1, 2021 An international team of researchers (USA – Los Alamos National Laboratory, Rice University, Northwestern University, France) has discovered efficient, regenerative, and low-cost electron sources based on solution-processed halide perovskites thin films when they are excited with light with energy equal to or above their bandgap. They measured a quantum efficiency up to 2.2% and a lifetime of more than 25 h. Importantly, even after degradation, the electron emission could be completely regenerated to its maximum efficiency by deposition of a monolayer of alkali antimonide and tellurides (Cs2Te, K2CsSb, Cs3Sb). The electron emission from halide perovskites can be […]
Category Archives: Advanced materials
Researchers construct molecular nanofibers that are stronger than steel
MIT News January 25, 2021 Small-molecule self-assembly is an established route for producing high-surface-area nanostructures with readily customizable chemistries and precise molecular organization. The whole structure falls apart when you remove water, particularly when any kind of external force is applied. An international team of researchers (USA – MIT, Argonne National Laboratory, France) has shown that a small-molecule platform, the aramid amphiphile overcomes these dynamic instabilities by incorporating a Kevlar-inspired domain into the molecular structure. Strong, anisotropic interactions between aramid amphiphiles suppress molecular exchange and elicit spontaneous self-assembly in water to form nanoribbons with lengths of up to 20 micrometres. […]
Solar material can ‘self-heal’ imperfections, new research shows
Phys.org January 27, 2021 Broken bonds introduced at extended defects in covalently bonded semiconductors generally introduce deep electronic states within the gap, negatively impacting performance for applications in electronics, photochemistry, and optoelectronics. Researchers in the UK found that Sb2Se3 and Sb2S3, which show exceptional promise for photovoltaic and photoelectrochemical applications, exhibit a remarkable ability to self‐heal broken bonds through structural reconstructions, thereby eliminating the associated deep electronic states. These materials appear intrinsically resilient to the formation of dangling bonds at extended defects, which should be advantageous for a wide range of applications. They could reduce costs and improve scalability of […]
New metamaterial offers reprogrammable properties
Science Daily January 22, 2021 Researchers in Switzerland have developed metamaterial made of silicon and magnetic powder which has a complicated structure that allows mechanical properties to vary. Each cell within the structure behaves like an electrical switch. It is possible to activate and deactivate individual cells by applying a magnetic field which modifies the internal state of the metamaterial, and consequently its mechanical properties. The programmable material is analogous to computer devices like hard drives. The devices contain bits of data that can be written to and read from in real time. The cells in this programmable metamaterial, called […]
New state of matter in one-dimensional quantum gas
Phys.org January 14, 2021 Long-lived excited states of interacting quantum systems that retain quantum correlations and evade thermalization are of great fundamental interest. A team of researchers in the US (Stanford University, City University of New York) created nonthermal states in a bosonic one-dimensional (1D) quantum gas of dysprosium by stabilizing a super-Tonks-Girardeau gas against collapse and thermalization with repulsive long-range dipolar interactions. Stiffness and energy-per-particle measurements show that the system is dynamically stable regardless of contact interaction strength. This enables us to cycle contact interactions from weakly to strongly repulsive, then strongly attractive, and finally weakly attractive. They showed […]
Extremely fast electrochromic supercapacitors
Phys.org January 7, 2021 Mesoporous metal oxides consisting of fully interconnected network structures with small pores have high surface areas and decreased ion intercalation distances, making them ideal for use in high-performance electrochromic supercapacitors. An international team of researchers (South Korea, Sweden) used an evaporation-induced self-assembly process to deposit a film of tungsten trioxide with pores, where the porous architecture increased the speed of switching and capacitance in the material compared to conventional tungsten trioxide thin films. They developed multifunctional electrochromic supercapacitors based on amorphous mesoporous WO3 films. They attribute its superior performance to its large surface area and amorphous […]
Neither liquid nor solid
Science Daily January 5, 2021 Most experiments involving colloidal suspensions have relied on spherical colloids. Using polymer chemistry researchers in Germany manufactured small plastic particles, stretching, and cooling them until they achieved their ellipsoid forms and then placed them in a suitable solvent. They found that due to their distinct shapes their particles had orientation which gave rise to entirely new and previously unstudied kinds of complex behaviours. By changing particle concentrations in the suspensions, and tracking both the translational and rotational motion of the particles using confocal microscopy, they observed two competing glass transitions — a regular phase transformation […]
Scrambled supersolids: Soft form of a solid discovered
Science Daily January 4, 2021 An international team of researchers (Austria, Switzerland) created supersolids using ultracold quantum gases of highly magnetic lanthanide atoms. This state of matter is solid and liquid at the same time. Due to quantum effects, a very cold gas of atoms can spontaneously develop both a crystalline order of a solid crystal and particle flow like a superfluid quantum liquid. A dipolar supersolid can be imagined as a chain of quantum droplets which communicate with each other via a superfluid background bath. They found that if the superfluid bath between the droplets is drained by control […]
Chemists convert plastic bottle waste into insecticide sorbent
Phys.org December 23, 2020 An international team of researchers (Russia, China, Czech Republic, South Korea) created a sorbent that belongs to metal-organic frameworks, for imidacloprid insecticide removal from water. They developed a method to synthesize a metal-organic framework named UiO-66 with zirconium ions. The framework is sensitive to imidacloprid and due to its porosity and physicochemical properties, it attracts insecticide molecules removing them from water. In tests effective water purification took 15 grams of sorbent per liter. The sorbent may be reused several times. They reached up to five cycles during experiments. In the future the sorbent can be used […]
Physics breakthrough of the year
EurekAlert December 17, 2020 Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon, germanium and SiGe alloys are all indirect-bandgap semiconductors that cannot emit light efficiently. An international team of researchers (Canada, the Netherlands, Germany, Austria) has demonstrated efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. They measured a sub-nanosecond, temperature-insensitive radiative recombination lifetime and observed an emission yield similar to that of direct-bandgap group-III–V semiconductors. They demonstrated that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously […]