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 […]
Category Archives: Materials science
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
From face recognition to phase recognition
Nanowerk May 31, 2018 An international team of researchers (USA – Stony Brook University, Brookhaven National Laboratory, Latvia) has developed a tool to extract “hidden” signatures of an unknown structure from measurements made by existing tools. The network training is similar to how machine learning is used in facial-recognition technology. The technique is useful for studying the dynamics of phase changes, and to monitor the arrangements of nanoparticles in catalysts and other materials… read more. TECHNICAL ARTICLE
3D-printed smart gel that walks underwater, moves objects
Science Daily May 18, 2018 During the printing a walker, an international team of researchers (USA – Rutgers University, South Korea) projected light on a light-sensitive solution that becomes a gel. The hydrogel was placed in an electrolyte. Two thin wires applied electricity to trigger motion – walking forward, reversing course and grabbing and moving objects. The speed of the smart gel’s movement is controlled by changing its dimensions (thin is faster than thick), and the gel bends or changes shape depending on the strength of the salty water solution and electric field. It has applications in biomedical engineering and […]
Keep the light off: A material with improved mechanical performance in the dark
Phys.org May 17, 2018 Researchers in Japan have shown that when crystals of zinc sulfide are kept in the dark at room temperature, they deformed plastically without fracture until a large strain of 45%. The high plasticity was accompanied by a considerable decrease in the band gap of the deformed crystals increasing their electrical conductivity which may be controlled by mechanical deformation. According to the researchers the decreased band gap was caused by deformation introducing dislocations into the crystals, which changed their band structure. The findings open avenue to optimize the performance of inorganic semiconductors in electronics… read more. TECHNICAL […]
Supersonic waves may help electronics beat the heat
Science Daily May 17, 2018 A team of researchers in the US (Oak Ridge National Laboratory, industry) has demonstrated supersonic channel for the propagation of lattice energy in fresnoite (Ba2TiSi2O8) using neutron scattering. Lattice energy propagates 2.8−4.3 times the speed of sound in the form of phasons, which are caused by an incommensurate modulation in the flexible framework structure of fresnoite. The phasons enhance the thermal conductivity by 20% at room temperature and carry lattice-energy signals at speeds beyond the limits of phonons. The discovery may dramatically improve heat transport in insulators and enable new strategies for heat management in […]
Water-repellent surfaces can efficiently boil water, keep electronics cool
Nanowerk April 30, 2018 Researchers at Purdue University first submerged the superhydrophobic surface and then heated the surrounding water, being careful to not boil directly from the surface itself. Doing so removed the layer of air that is normally trapped within the texture of the superhydrophobic surface, allowing water to penetrate the texture and fully wet it, as it would for a hydrophilic surface. This resulted in the “pinning” of small bubbles during boiling, making them depart without coalescing into a vapor blanket and help keep the surface wet with liquid water. Hydrophobic materials are also able to form many […]