Guidelines Clarify Origins of Ferroelectric Signals
July 21, 2015 — Recent developments in piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical hysteresis loops in a variety of materials including inorganic oxides, polymers and bio systems. This behavior is often (mis)interpreted as evidence of ferroelectricity.
Electron Beam Guides Engineering of Functional Defects
May 20, 2015 — The electron beam of a scanning transmission electron microscope was applied to generate Se vacancies in a semiconducting monolayer of MoSe2, provide energy to drive the formation and growth of inversion domains and metallic 60˚ grain boundaries, and track the dynamics.
True structure of pnictide 122 superconductors revealed
April 13, 2015 — High-resolution microscopy revealed an unexpected room-temperature crystal structure of the ‘122’ Ba(Fe1-xCox)2As2 superconductors, with domains similar to those in ferroelectrics but with nanometer size.
Atomic-Scale Observations Aid Mesoscale Catalyst Design
April 08, 2015 — Two phases of Mo-V-O–based oxides, M1 and M2, are promising catalysts for direct conversion of propane to acrylonitrile and are believed to act synergistically. Researchers engineered the mesoscale structure of M1- and M2-phase oxides to amplify these effects, greatly improving selectivity for propane ammoxidation.
Technique Recovers Atomic Resolution in Spectrum Images
April 08, 2015 — Researchers have demonstrated a technique for obtaining atomic-resolution information from spectrum images of thick specimens of MnFePSi compounds, which are promising for ecofriendly refrigeration. This technique allows the quantitative examination of specimens for which atomic-resolution spectroscopic analysis was previously impossible.
Dynamic coupling drives conformational evolution of branched polymers in solutions
March 06, 2015 — The critical overlap concentration of polymer solutions, denoted c*, is one of the most important characteristic values of a polymer solution. This geometrically defined parameter is used to identify concentration regimes with different conformational characteristics.
New Atomic Force Microscope Spectroscopy Probes Local Elasticity
March 04, 2015 — Contact resonance imaging and voltage spectroscopy based on photothermal excitation were developed to explore local bias-induced phenomena. These techniques can access nanoscale elastic properties in real time during polarization switching in ferroelectric nonvolatile memories, and during ion intercalation in batteries and supercapacitors.
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.
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.
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.