Nanowerk July 27, 2023 When in equilibrium, thermal forces agitate molecules, which then diffuse, collide, and bind to form materials. However, the space of accessible structures in which micron-scale particles can be organized by thermal forces is limited, owing to the slow dynamics and metastable states. Active agents in a passive fluid generate forces and flows, forming a bath with active fluctuations. Two unanswered questions are whether those active agents can drive the assembly of passive components into unconventional states and which material properties they will exhibit. Researchers in Austria showed that passive, sticky beads immersed in a bath of […]
Tag Archives: Materials science
MIT engineers create an energy-storing supercapacitor from ancient materials
MIT News July 31, 2023 A team of researchers in the US (MIT, Harvard University) investigated using cement, water, and carbon black as chemical precursors for energy storage. Texture analysis revealed that the hydration reactions of cement in the presence of carbon generates a fractal-like electron-conducting carbon network that permeates the load-bearing cement-based matrix. The energy storage capacity of this space-filling carbon black network of the high specific surface area accessible to charge storage was shown to be an intensive quantity, whereas the high-rate capability of the carbon-cement electrodes exhibited self-similarity due to the hydration porosity available for charge transport. […]
‘Quantum avalanche’ explains how nonconductors turn into conductors
Phys.org July 24, 2023 The significant discrepancy observed between the predicted and experimental switching fields in correlated insulators under a DC electric field far-from-equilibrium necessitates a reevaluation of current microscopic understanding. An international team of researchers (USA – SUNY Buffalo, France, South Korea) has shown that an electron avalanche can occur in the bulk limit of such insulators at arbitrarily small electric field by introducing a generic model of electrons coupled to an inelastic medium of phonons. The quantum avalanche arose because of the generation of a ladder of in-gap states, created by a multi-phonon emission process. Hot-phonons in the […]
Aluminum materials show promising performance for safer, cheaper, more powerful batteries
Science Daily July 19, 2023 Metal negative electrodes that alloy with lithium have high theoretical charge storage capacity and are ideal candidates for developing high-energy rechargeable batteries. However, such electrode materials show limited reversibility in Li-ion batteries with standard non-aqueous liquid electrolyte solutions. A team of researchers in the US (Georgia Institute of Technology, industry) used non-pre-lithiated aluminum-foil-based negative electrodes with engineered microstructures in an all-solid-state Li-ion cell configuration. When a 30-μm-thick Al94.5In5.5 negative electrode is combined with a Li6PS5Cl solid-state electrolyte and a LiNi0.6Mn0.2Co0.2O2-based positive electrode, lab-scale cells delivered hundreds of stable cycles with practically relevant areal capacities at […]
Proposed metamaterial could have a wide range of applications, from sensing to stealth technology
Phys.org July 17, 2023 Materials scientists are actively hunting for metamaterials that are “perfect absorbers” of electromagnetic radiation with controllable resonance characteristics that lead to their wide usage in applications as varied as solar cells, thermal radiation imaging, sensing technology, and even stealth technology. An international team of researchers (Pakistan, USA – University of Alabama) has developed a triple-band perfect metamaterial absorber in terahertz regime that is made of asymmetric metallic I-shaped resonator and metallic ground layer with dielectric spacer in the middle. The simulated results showed that the absorption device had three resonance modes with corresponding absorption rate close […]
Thanks to trapped electrons, a material expected to be a conducting metal remains an insulator
Nanowerk July 13, 2023 Doped antiferromagnets host a vast array of physical properties and learning how to control them is one of the biggest challenges of condensed matter physics. La1.67Sr0.33NiO4 (LSNO) is a classic example of such a material. At low temperatures holes introduced via substitution of La by Sr segregate into lines to form boundaries between magnetically ordered domains in the form of stripes. The stripes become dynamic at high temperatures, but LSNO remains insulating presumably because an interplay between magnetic correlations and electron–phonon coupling localizes charge carriers. Magnetic degrees of freedom have been extensively investigated in this system, […]
New material shows promise for next-generation memory technology
Nanowerk July 10, 2023 Phase change memory could potentially revolutionize data storage because of its high storage density, and faster read and write capabilities. But still, the complex switching mechanism and intricate fabrication methods associated with these materials have posed challenges for mass production. Unlike conventional amorphous-crystalline PCMs, NbTe4 demonstrates both a low melting point and a high crystallization temperature. This unique combination offers reduced reset energies and improved thermal stability at the amorphous phase. Researchers in Japan fabricated NbTe4 and evaluated its switching performance. It exhibited a significant reduction in operation energy compared to conventional phase-change memory compounds. The […]
Scientists develop 2D nanosheets for sustainable carbon capture
Phys.org July 6, 2023 Mica, a commonly occurring mineral, has significant potential for various applications due to its unique structure and properties. However, due to its non-Van Der Waals bonded structure, it is difficult to exfoliate mica into ultrathin nanosheets. Researchers in Singapore characterized exfoliated 2D mica nanosheets (eMica nanosheets) by various techniques, and their ability to capture CO2 was tested by thermogravimetric analysis (TGA). Their results showed an 87% increase in CO2 adsorption capacity with eMica nanosheets compared to conventional mica. Further characterization by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), as well as first-principles calculations, showed […]
Unraveling the hidden growth of mineral dendrites
Phys.org July 10, 2023 Manganese (Mn) dendrites are a common type of mineral dendrite that typically forms two-dimensional structures on rock surfaces. Three-dimensional (3-D) Mn dendrites in rocks have rarely been reported, and so their growth implications have largely escaped attention. Understanding the dynamics of the growth of three-dimensional mineral dendrites is important for various fields of science—physics, geology, material sciences and even the study of extraterrestrial environments. An international team of researchers (Austria, Poland, UK) combined high-resolution X-ray and electron-based data with numerical modeling to give the first detailed description of natural 3-D Mn dendrites (in clinoptilolite tuffs) and […]
Researchers create antenna for nanoscale light sources using unusual placement of semiconductor material
Phys.org July 3, 2023 Two-dimensional van der Waals materials are an excellent platform for the study of materials with well-defined interfaces. Signatures of acoustic phonons and defect states have been observed in current-to-voltage measurements. These features can be explained by direct electron–phonon or electron–defect interactions. An international team of researchers (Switzerland, Spain, Japan) used a tunnelling process that involved excitons in transition metal dichalcogenides (TMDs). They studied the tunnel junctions consisting of graphene and gold electrodes separated by hexagonal boron nitride with an adjacent TMD monolayer and observed prominent resonant features in current-to-voltage measurements appearing at bias voltages that corresponded […]