Phys.org January 3, 2023 The aggressive oxidizing conditions typically used in growing epitaxial oxides can damage graphene. A team of researchers in the US (University of Minnesota, Pacific Northwest National Laboratory, University of Wisconsin) used hybrid molecular beam epitaxy for SrTiO3 growth that did not require an independent oxygen source, thus avoided graphene damage. They produced epitaxial films with self-regulating cation stoichiometry. The film could be exfoliated and transferred to foreign substrates. The results opened the door to future studies of previously unattainable freestanding oxide nanomembranes grown in an adsorption-controlled manner by hybrid molecular beam epitaxy. According to the researchers […]
Tag Archives: Material science
Thinnest ferroelectric material ever paves the way for new energy-efficient devices
Phys.org October 19, 2022 In many materials the ferroelectric behavior is suppressed at the few-nanometer scale. A team of researchers in the US (UC Berkeley, State University of Pennsylvania, Argonne National Laboratory, Lawrence Berkeley National Laboratory) found that ferroelectricity emerges in zirconium dioxide when it is grown extremely thin, approximately 1-2 nanometers in thickness. Notably, the ferroelectric behavior continues to its near-atomic-scale thickness limit of roughly half a nanometer. This approach to exploit three-dimensional centrosymmetric materials deposited down to the two-dimensional thickness limit, particularly within this model fluorite-structure system that possesses unconventional ferroelectric size effects, offers substantial promise for electronics, […]
Optical cavities could provide new technological possibilities
Phys.org May 12, 2022 Coupling between molecules and vacuum photon fields inside an optical cavity has proven to be an effective way to engineer molecular properties, in particular reactivity. An international team of researchers (Norway, Italy) studied optical cavities and how the light trapped in them interacts with atoms, molecules, and other particles. Their framework explained modifications of the electronic structure due to the interaction with the photon field. They showed that the newly developed orbital theory could be used to predict cavity induced modifications of molecular reactivity and pinpoint classes of systems with significant cavity effects. They also investigated […]
UCLA materials scientists lead global team in finding solutions to biggest hurdle for solar cell technology
EurekAlert March 15, 2022 Optoelectronic devices consist of heterointerfaces formed between dissimilar semiconducting materials. The relative energy level alignment between contacting semiconductors determinately affects the heterointerface charge injection and extraction dynamics. For perovskite solar cells (PSCs), the heterointerface between the top perovskite surface and a charge-transporting material (CTM) is often treated for defect passivation to improve PSC stability and performance. However, such surface treatments could also affect the heterointerface energetics. An international team of researchers (USA – UCLA, UC Irvine, Turkey, South Korea, Taiwan) has shown that surface treatments may induce a negative work function shift (i.e., more n-type), which […]
Skyrmion research: Braids of nanovortices discovered
Phys.org October 6, 2021 Braided structures are commonly seen in nature. An international team of researchers (Germany, Sweden, China) has discovered that such structures exist on the nanoscale in alloys of iron and the metalloid germanium. These nanostrings are each made up of several skyrmions that are twisted together to a greater or lesser extent, rather like the strands of a rope. Each skyrmion itself consists of magnetic moments that point in different directions and together take the form of an elongated tiny vortex. The length of the magnetic structures is limited only by the thickness of the sample. Earlier […]
3D Kirigami Building Blocks Designed To Make Dynamic Metamaterial Structures
ScitechDaily.com August 11, 2021 In a proof-of-concept study a team of researchers in the US (North Carolina State University, Yale University) cut bulk materials into spatially closed-loop to construct a new class of 3D kirigami metamaterials. The module is transformable with multiple degrees of freedom that can transform into versatile distinct daughter building blocks. Depending on how the cubes are connected to each other, the building blocks can be folded into more than 300,000 different designs. Their conformable assembly creates a wealth of reconfigurable and disassemblable metamaterials with diverse structures and unique properties, including reconfigurable 1D column-like materials, 2D lattice-like […]
An 18-carat gold nugget made of plastic
EurekAlert January 8, 2020 Researchers in Switzerland have developed a material via a hydrogel precursor dried into an aerogel. Annealing of the polystyrene matrix under vacuum gives rise to a homogeneous template. The final apparent density and porosity of the material depend directly on the volumetric concentration of the starting solution used for hydrogel formation. After annealing, a homogeneous microstructure is obtained in which the shining gold single crystal platelets are evenly embedded in a polystyrene matrix. The material has a glass transition temperature of ≈105 °C, the Young’s modulus of the material with a density of 1.7 g cm−3 […]