Crown Ethers in Graphene Bring Strong, Selective Binding
November 14, 2014 — Researchers discovered the long-sought crown ether structures with perfect rigidity in oxidized atomic-scale holes in graphene. Calculations indicate that these “super crown ethers” provide unprecedented binding strength and selectivity. Thus, new supramolecular materials in which metal ions are trapped into arrays within the graphene plane are possible.
Strain-induced vacancy stability shown across an interface
November 12, 2014 — Density functional theory (DFT) calculations show that among the four types of (001) SrTiO3 | (001) MgO interface structures, the TiO2-terminated SrTiO3 containing electrostatically attractive Mg–O and Ti–O ion–ion interactions form the most stable interface.
Shaking the bonds: Atomic vibrations drive insulator to metal
November 10, 2014 — Neutron and x-ray experiments, coupled with large-scale first-principles calculations have revealed the origin of the metal–insulator transition in vanadium dioxide, an intractable question in phase stability for more than 50 years.
Stable Separator Identified for High-Energy Batteries
November 04, 2014 — State-of-the-art scanning transmission electron microscopy (STEM) unveiled the structural stability of lithium lanthanum zirconium oxide (LLZO) garnet in aqueous media.
New Method Probes Nanoscale Electrostatic Effects
October 29, 2014 — Electrostatic forces were used to observe charge transfer at the nanoscale between metal and dielectric materials. A new technique was developed to access information about charge transfer, which is a key component in processes such as storage in flash memories, electroforming in memristors, surface electrochemistry, and triboelectricity.
Digital Transfer Growth of Patterned 2D Metal Chalcogenides by Confined Nanoparticle Evaporation
October 28, 2014 — Researchers demonstrated a novel growth technique for the controlled synthesis of monolayer or few-layer 2D metal chalcogenide crystals that should prove useful for their scaled production for optoelectronic and energy applications.
A High-Energy Solid State Battery with an Extremely Long Cycle Life
October 15, 2014 — A high-voltage (5V) solid state battery has been demonstrated to have an extremely long cycle life of over 10,000 cycles. For a given size of battery, the energy stored in a battery is proportional to its voltage. Conventional lithium-ion batteries use organic liquid electrolytes that have a maximum operating voltage of 4.3 V.
Characterizing Performance of Nanostructured Alloys for Extreme Environments
October 14, 2014 — In situ neutron diffraction characterization of strains in nanostructured materials reveals, for the first time, a large temperature-sensitive elastic anisotropy and a deformation crossover upon extensive straining. The novel approach utilized to determine single-crystal elastic constants provides a new strategy for characterizing anisotropic elasticity of complex materials.
Tracking dopant diffusion pathways in bulk semiconductors
October 07, 2014 — A scanning transmission electron microscope (STEM) is used to locally excite and directly image the diffusion of single dopant atoms inside bulk single crystals. Although diffusion is a fundamental process that governs the structure, processing and properties of most materials, direct observations of diffusion processes have been elusive and limited to the surfaces of materials, until this work.
Importance of diminished local structural distortions and magnetism in causing iron-based superconductivity
September 29, 2014 — By analyzing the role of structural variation and magnetism of Cu dopants in FeAs planes, researchers demonstrated that orthorhombic distortions that give strong spin-density-wave spin (SDW) fluctuations are detrimental to superconductivity in BaFe2As2. The results provide new information about the interplay between local composition, magnetism and superconductivity.