Science Daily August 8, 2018 An international team of researchers (USA – Lawrence Berkeley National Laboratory, UC Berkeley, UMass Amherst, Japan) put a droplet of a liquid containing iron oxide nanocrystals into an oily liquid containing tiny polymer strands and cause the nanoparticles assembled here to jam, making it act like a solid, and then to unjam and return to a liquid-like state by the competitive push-pull action of the polymer and the additive. They can control the rate at which this happens through the use of a ligand at a defined concentration and manipulate the properties of the liquid […]
Category Archives: Materials science
Close-ups of grain boundaries reveal how sulfur impurities make nickel brittle
Eurekalert July 17, 2018 It is known that sulfur embrittlement is related to the grain boundary segregation of sulfur, but the underlying atomic mechanisms have remained elusive. Researchers at UC San Diego examined the general grain boundaries in nickel polycrystals doped with sulfur. They found that competition between interfacial ordering and disordering leads to the alternating formation of amorphous-like and bilayer-like facets at general grain boundaries. They also found that bipolar interfacial structures cause brittle intergranular fractures between polar sulfur-nickel structures that are disorderly aligned in two opposite directions. The discovery enriches fundamental understanding of general grain boundaries that often […]
Slippery when dry
Phys.org July 13, 2018 Researchers at Argonne National Laboratory have developed a process based on graphene which shows that a few layers of graphene not only reduce friction in steel rubbing against steel by seven times and the wear by 10,000 times but also significantly reduces the tribo-corrosion problem. Graphene can be applied by spraying a solution in the air and can coat any complicated shape or size—and over a large surface area. According to the researchers it could help wind turbines move with greater ease, allowing them to produce more energy. It can better seal off machinery as it […]
Solutions to water challenges reside at the interface
Phys.org July 17, 2018 Interfaces between components of water systems and the water-based fluids themselves govern the performance of the vast majority of water treatment and conveyance processes. A team of researchers in the US (Argonne National Laboratory, University of Chicago) examines many of these interfaces, ranging from those in sorbents and sensors to membranes and catalysts, and surveys opportunities for scientists and engineers to reveal new insights into their function and, thereby, to design novel technologies for next-generation solutions to our collective energy-water challenges… read more. Open Access TECHNICAL ARTICLE
Electrons slowing down at critical moments
Nanowerk July 7, 2018 An international team of researchers (USA – Argonne National Laboratory, Northwestern University, University of Illinois, Ireland) has shown an unusual slowing down of the recovery of an electronic phase across a first-order phase transition. Following optical excitation, the recovery time of both transient optical reflectivity and X-ray diffraction intensity from the charge-ordered superstructure in a La1/3Sr2/3FeO3 thin film increases by orders of magnitude as the sample temperature approaches the phase transition temperature. In this regime, the recovery time becomes much longer than the lattice cooling time. According to the researchers the abnormal behavior of electrons is […]
The culprit of some GaN defects could be nitrogen
Nanowerk June 29, 2018 Gallium nitride’s defects and degradation are due to the atoms being displaced in the crystal lattice structure. An international team of researchers (Greece, Algeria, France) used computational analysis to determine the structural and electronic properties of a-type basal edge dislocations along the <1-100> direction in GaN which are common in semipolar growth orientations. They studied three models with different core configurations – three nitrogen atoms and one gallium atom for the Ga polarity; four N atoms and two Ga atoms; two N atoms and two Ga core-associated atoms. They found a connection between the smaller bandgap […]
Graphene forms electrically charged crinkles
Science Daily June 27, 2018 Researcher at Brown University have discovered a new, curvature-localizing, subcritical buckling mode that produces shallow-kink corrugation in multi-layer graphene. Density functional theory analysis reveals the curvature that connects two regions of uniformly but oppositely sheared stacks of flat atomic sheets. The high polarization concentration, predicted by the model, can be controlled by macroscopic deformation and is expected to be useful in studies of selective graphene-surface functionalization for various applications… read more. TECHNICAL ARTICLE
New approach to generating ultrashort laser pulses
Nanowerk June 8, 2018 An international team of researchers (USA – MIT, The Ohio State University, Germany) used an optical parametric amplifier to produce pulses which cover different spectral ranges and whose amplitudes and phases can be fixed relative to one another. The amplifier has a very short time delay between the two pulses so that they combine into a wide-bandwidth pulse with no need for noise control. The pulse could be made even shorter than the period of the wave because constructive interference occurs at its center, while destructive interference ‘trims’ the pulse at its edges. When the pulses […]
Scientists find ordered magnetic patterns in disordered magnetic material
Science Daily June 8, 2018 A team of researchers in the US (Lawrence Berkeley National Laboratory, UC Berkeley) has generalized the concept of chirality driven by interfacial the Dzyaloshinskii–Moriya interaction (DMI) to complex multicomponent systems and demonstrated on the example of chiral ferrimagnetism in amorphous GdCo films. They found that 2 nm thick GdCo films preserve ferrimagnetism and stabilize chiral domain walls. The type of chiral domain walls depends on the rare‐earth composition/saturation magnetization. The success of the experiments opens the possibility of controlling some properties of domain walls, such as chirality, with temperature, and of switching a material’s chiral […]
Building nanomaterials for next-generation computing
Science Daily May 30, 2018 Researchers at Northwestern University tested different conditions to map out the different parameters required to grow specific heterostructures from four types of 2-D materials: molybdenum disulfide and diselenide, and tungsten disulfide and diselenide. The unified Time-Temperature-Architecture Diagrams provide directions for the exact conditions required to generate numerous heterostructure morphologies and compositions. Using these diagrams, the researchers developed a unique library of nanostructures with physical properties of interest to physicists and materials scientists which may be useful for heterostructure fabrication beyond the first four materials… read more. Open Access TECHNICAL ARTICLE