Phys.org November 10, 2020 To create devices that mimic what occurs in our brain’s neurons and synapses, researchers need to overcome a fundamental molecular engineering challenge: how to design devices that exhibit controllable and energy-efficient transition between different resistive states triggered by incoming stimuli. A team of researchers in the US (University of Chicago, Argonne National Laboratory) investigated the defective cobaltites and unraveled the structural, electronic, and magnetic changes responsible for the metal-to-insulator transition (MIT) when oxygen vacancies are introduced in the material. They showed that cooperative structural distortions instead of local bonding changes are responsible for the MIT, described […]
Category Archives: Materials science
Sticky electrons: When repulsion turns into attraction
EurekAlert November 10, 2020 A few years ago, researchers in Austria were able to clarify mathematically where the boundary lies between the area that follows the known rules and the area where unusual effects play an important role. An international team of researchers (Austria, USA – Georgetown University, Italy, Germany) with the help of complex calculations on supercomputers, has explained exactly what happens when this boundary is crossed: the repulsion between the electrons is suddenly counteracted by an additional attractive force that enables completely counterintuitive effects. By decomposing local and uniform susceptibilities of the Hubbard model via their spectral representations, […]
Geologists solve puzzle that could predict valuable rare earth element deposits
Science Daily October 9, 2020 Carbonatites and associated rocks are the main source of rare earth elements (REEs). REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. An international team of researchers (UK, Australia) conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light and heavy REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. […]
Mineral undergoes self-healing of irradiation damage
Phys.org September 9, 2020 Monazite–(Ce) is a common accessory rock component that bears petrogenetic information, which is widely used in geochronology and thermochronology, and is considered a potential host material for immobilization of radioactive waste. An international team of researchers (Austria, Germany, Russia, Czech Republic) conducted an ion-irradiation study that has unraveled the causes of the self-healing of monazite. They found that only in radiation-damaged monazite–(Ce), 4He ions cause gradual structural restoration. In contrast, its high-temperature annealed analogue and synthetic CePO4 experience He-irradiation damage. Alpha-assisted annealing contributes to preventing irradiation-induced amorphization of monazite–(Ce); however, this process is only significant above […]
Researchers capture footage of fluid behaving like a solid
Phys.org August 14, 2020 To study the Discontinuous Shear Thickening (DST) researchers in the UK used regular kitchen corn starch mixed with water, placed this in a narrow cell and released pressurized air into the cornstarch-water fluid. They observed three distinct pattern morphologies: viscous fingering, dendritic fracturing, and system-wide fracturing, which correspond to the same packing fraction ranges as weak shear thickening, discontinuous shear thickening, and shear-jammed regimes. DST behaviour could be used to calibrate future theoretical models for unique engineering applications such as soft body armour, “smart” speed bumps, and food production…read more. Open Access TECHNICAL ARTICLE
‘Tantalizing’ clues about why a mysterious material switches from conductor to insulator
Nanowerk May 18, 2020 Researchers in Japan created crystals of tantalum disulfide and then cleaved the crystals in a vacuum to reveal ultra-clean surfaces which they examined, at a temperature close to absolute zero. Using quantum tunneling they studied the degree of conducting behavior of the material. The results showed that there was indeed a stacking of layers which effectively arranged them into pairs. Sometimes the crystals cleaved between the pairs of layers, and sometimes through a pair, breaking it. They performed spectroscopy on both the paired and unpaired layers and found that even the unpaired ones are insulating, leaving […]
Dirty carbon reveals a sophisticated side
MIT News April 27, 2020 Polycyclic heavy hydrocarbons (HHs) such as coal, tar, and pitch are a family of materials with extremely rich and complex chemistry, representing a massive opportunity for their use in a range of potential applications. An international team of researchers (USA – MIT, industry, Canada, China) shows that optimal selection of initial HHs based on molecular constituents is essential in tuning the material for a particular and targeted electronic application. Combining the selection of feedstock chemistry (H:C and aromatic content) and controlling variable laser treatment parameters (laser power, speed, and focus) lead to full control over […]
Unlocking promising properties to create future technologies
EurekAlert April 30, 2020 The manifestation of quantization in macroscopic physical systems has showcased important quantum phenomena, such as quantized conductance in (fractional) quantum Hall effects and quantized vortices in superconductors. An international team of researchers (USA – Rensselaer Polytechnic Institute, Florida State University, UT Dallas, Arizona State University, Japan, Hong Kong) reported the experimental observation of quantized exciton energies in a macroscopic system with strong Coulomb interaction, monolayer WSe2 crystal under a strong magnetic field. This work demonstrates the optical version of the QHE for excitons, and the researchers believe it will open the door for further discovery and […]
Researchers created a tiny circuit through a single water molecule
Phys.org April 20, 2020 Water molecules can mediate charge transfer in biological and chemical reactions by forming electronic coupling pathways. Through molecular-level (Duke University, Arizona State University, Pennsylvania State University, UC Davis) has shown that there are two distinct states of water, corresponding to parallel and perpendicular orientations of the molecules. Water molecules switch from parallel to perpendicular orientations on applying an electric field, producing a switch from high- to low-conductance states, thus enabling the determination of single water molecular dipole moments. Water-water interactions affect the atomic-scale configuration and conductance of water molecules. These findings demonstrate the importance of the […]
Novel graphene-based filters to make gas purification more effective
Nanowerk March 27, 2020 Precise molecular sieving is potentially possible using graphene oxide‐based membranes, if the porosity can be matched with the kinetic diameters of the gas molecules, which is possible via the tuning of graphene oxide interlayer spacing to take advantage of gas species interactions with graphene oxide channels. An international team of researchers (Australia, South Korea) have shown highly effective separation of gases from their mixtures by using uniquely tailored porosity in mildly reduced graphene oxide (rGO) based membranes. The study will lead to new avenues for the applications of graphene for efficiently separating CO2 from N2 and […]