Phys.org March 18, 2024 Freestanding oxide membranes have a variety of interesting applications, but pulling these materials off the substrate after synthesis can be challenging. An international team of researchers (China, Austria) has developed a water-soluble sacrificial layer, “super-tetragonal” Sr4Al2O7 (SAOT). The low-symmetric crystal structure enabled a superior capability to sustain epitaxial strain, allowing for broad tunability in lattice constants resulting in structural coherency and defect-free interface in perovskite ABO3/SAOT heterostructures effectively restraining crack formation during the water release of freestanding oxide membranes. For a variety of nonferroelectric oxide membranes, the crack-free areas can span up to a millimeter in […]
Author Archives: Hema Viswanath
Researchers discover new yttrium-hydrogen compounds with implications for high-pressure superconductivity
Phys.org March 14, 2024 An international team of researchers (Germany, UK, USA – University of Chicago) used synchrotron single-crystal x-ray diffraction (SCXRD) and found (two YH3 phases) and five previously unknown yttrium hydrides. These were synthesized in diamond anvil cells by laser heating yttrium with hydrogen-rich precursors—ammonia borane or paraffin oil. The arrangements of yttrium atoms in the crystal structures of new phases were determined based on SCXRD, and the hydrogen content estimations based on empirical relations and ab initio calculations revealed the following compounds: Y3H11, Y2H9, Y4H23, Y13H75, and Y4H25. They also uncovered a carbide and two yttrium allotropes. […]
Researchers prove fundamental limits of electromagnetic energy absorption
Phys.org March 14, 2024 Past work has considered the analytic properties of the reflection coefficient for a metal-backed slab and established a fundamental relationship for the minimal layer thickness to bandwidth ratio achievable for an absorber, but a similar relationship for non-metal-backed layers is not established. Based on Kramers–Kronig relations researchers at Duke University have developed a universal result. They validated their theory with transfer matrix calculations of homogeneous materials, and full-wave numerical simulations of electromagnetic metamaterials. According to the researchers their results place more general fundamental limits on absorbers, and it will be important for both fundamental and applied […]
Supercomputer simulations of super-diamond suggest a path to its creation
Phys.org March 18, 2024 Despite several experimental attempts, synthesis, and recovery of the theoretically predicted post-diamond BC8 phase remains elusive. Through quantum-accurate multimillion atom molecular dynamics (MD) simulations, an international team of researchers (USA – University of South Florida, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sweden) uncovered the extreme metastability of diamond at very high pressures, significantly exceeding its range of thermodynamic stability. They predicted the post-diamond BC8 phase to be experimentally accessible only within a narrow high pressure–temperature region of the carbon phase diagram. The diamond to BC8 transformation proceeded through premelting followed by BC8 nucleation and […]
Top 10 Science and Technology Inventions for the Week of March 15, 2024
01. Researchers achieve quantum key distribution for cybersecurity in novel experiment 02. Materials research explores design rules and synthesis of quantum memory candidates 03. New research on tungsten unlocks potential for improving fusion materials 04. New type of tunable filter reveals the potential for terahertz wireless communications 05. Powerless mechanoluminescent touchscreen underwater 06. Preventing magnet meltdowns before they can start 07. Researchers generate super-fast electrons with table-top laser systems 08. Paper AI sensor mimics brain for health monitoring 09. Novel method improves Fourier transform infrared spectroscopy detection of ultra-low concentration trace substances 10. China promises more money for science in […]
A 3D view into chaos: Researchers visualize temperature-driven turbulence in liquid metal for the first time
Phys.org March 11, 2024 Researchers in Germany conducted an experiment inside a cylinder filled with the ternary alloy GaInSn focusing on the manifestation and dynamics of the large-scale circulation (LSC) in turbulent liquid metal convection. The large-scale flow structures were classified and characterized at Rayleigh numbers by means enabling the full reconstruction of the three-dimensional flow structures in the entire convection cell. They identified the dominating modes of the turbulent convection. The analysis revealed that a single-roll structure of the LSC alternates in short succession with double-roll structures or a three-roll structure. This was accompanied by dramatic fluctuations of the […]
China promises more money for science in 2024
Nature March 8, 2024 At its annual meeting this week, China’s legislative body, the National People’s Congress, promised to increase government funding for science by 10% in 2024. It’s the largest boost to funding in five years. The increase comes as the Chinese economy struggles to meet growth targets and is locked in a race for technological supremacy with the United States. “To win this game, China has to invest in science and technology, especially in basic research,” says Marina Zhang, who studies innovation with a focus on China… read more.
Doing more but learning less: Addressing the risks of AI in research
Phys.org March 8, 2024 Scientists are enthusiastically imagining ways in which artificial intelligence (AI) tools might improve research. A team of researchers in the US (Yale University, Princeton University) developed a taxonomy of scientists’ visions for AI, observing that their appeal comes from promises to improve productivity and objectivity by overcoming human shortcomings. But proposed AI solutions can also exploit our cognitive limitations, making us vulnerable to illusions of understanding in which we believe we understand more about the world than we actually do. Such illusions obscure the scientific community’s ability to see the formation of scientific monocultures, in which […]
Materials research explores design rules and synthesis of quantum memory candidates
Phys.org March 11, 2024 Stoichiometric Eu3+ compounds have recently shown promise for building dense, optically addressable quantum memory as the cations’ long nuclear spin coherence times and shielded 4f electron optical transitions provide reliable memory platforms but finding rare linewidth behavior within a wide range of potential chemical spaces remains difficult. Researchers at the University of Illinois, Urbana─Champaign, have found density functional theory (DFT) procedures that reliably reproduce known phase diagrams and correctly predict two experimentally realized quantum memory candidates. They synthesized the double perovskite halide Cs2NaEuF6 which is an air-stable compound with a calculated band gap of 5.0 eV […]
New research on tungsten unlocks potential for improving fusion materials
Phys.org March 13, 2024 Understanding phonon scattering has remained challenging and requires detailed information on interactions between phonons and electrons. An international team of researchers (USA – SLAC National Accelerator Laboratory, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Sweden, Italy) used an ultrafast electron diffuse scattering technique to resolve the nonequilibrium phonon dynamics in femtosecond–laser-excited tungsten in both time and momentum. They determined transient populations of phonon modes which show strong momentum dependence initiated by electron-phonon coupling. For phonons near Brillouin zone border, they observed a transient rise in their population on a timescale driven by the strong electron-phonon […]