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.
Metallic Glasses: Different Deformation Properties Underpinned by the Same Trigger
September 26, 2014 — A novel simulation approach demonstrates that a universal deformation trigger exists in metallic glasses and that the spatial organization of these triggers is closely related to the dynamics and stabilities of the system. This work demonstrates that a universal trigger initiates deformation and the organization of such triggers significantly affects bulk behavior.
Laser speckle analysis resolves mesoscale transitions
September 23, 2014 — An elegant experimental approach, which requires only simple and widely available equipment, provides previously inaccessible spatial and temporal resolution on coexisting electronic domains in a technologically promising transition-metal oxide.
Creating and Activating a Terahertz Nanorotor in Graphene
September 17, 2014 — Replacing a hexagonal ring of carbon atoms in a graphene layer with a silicon trimer results in a terahertz rotor (1012 rotations/sec) with low friction. This demonstrates that the ultimate miniaturization of a mechanical device (switch, oscillator, stirrer) down to a triangular arrangement of three atoms is possible.
Direct observation of ferroelectric field effect and oxygen vacancy screening at ferroelectric–metal interface
August 21, 2014 — Scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) studies of ferroelectric–metal interfaces revealed two distinct polarization charge screening mechanisms, with oxygen vacancies compensating negative charge and electrons compensating positive charge.
Magnetic fluctuations are good for superconductivity
August 15, 2014 — Atomic scale measurements of the strength of the magnetic fluctuations in a series of iron-based superconductors were made using high- resolution electron spectroscopy. Surprisingly, the superconducting transition temperature was higher when the magnitude of the fluctuating iron magnetic moment or “spin” was larger.
Thermopower Enhancement in Designer Oxide Superlattices
August 12, 2014 — A layer-by-layer design of 2D oxide superlattices with precisely controlled interface compositions has improved the thermopower of oxide thermoelectrics by 300% compared to that of bulk counterparts. Controlling the 2D carrier density through a new materials design strategy is critical for developing highly efficient thermoelectrics.