NIST measurements show that interactions of the graphene layers with the insulating substrate material causes electrons (red, down arrow) and electron holes (blue, up arrow) to collect in “puddles”. The differing charge densities creates the random pattern of alternating dipoles and electron band gaps that vary across the layers. Credit: NIST
NIST’s latest Tech Beat has many great stories of interest to readers interested in materials science:
Understanding how glasses ‘relax’ provides some relief for manufacturers
NIST theoretician Jack Douglas and his collaborator Francis Starr of Wesleyan University have used computer simulations to gain basic insights into a fundamental problem in material science related to glass-forming materials, offering a precise mathematical and physical description of the way temperature affects the rate of flow in this broad class of materials — a long-standing goal.
Two graphene layers may be better than one
Nikolai Zhitenev, Joseph Stroscio and other researchers at the institute have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results reveal that not only does the difference in the strength of the electric charges between the two layers vary across the layers, but they also actually reverse in sign to create randomly distributed puddles of alternating positive and negative charges. The new measurements bring graphene a step closer to being used in practical electronic devices.
Good eggs: Nanomagnets offer food for thought about computer memories
NIST researchers used electron-beam lithography to make thousands of nickel-iron magnets, each about 200 nanometers in diameter. Each magnet is ordinarily shaped like an ellipse, but the researchers also made some magnets in three different egglike shapes with an increasingly pointy end. It’s all part of NIST research on nanoscale magnetic materials, devices and measurement methods to support development of future magnetic data storage systems. It turns out that even small distortions in magnet shape can lead to significant changes in magnetic properties.
New manufacturing innovations blog lifts off
The manufacturing experts at NIST’s Hollings Manufacturing Extension Partnership are now spreading the word on manufacturing innovation by blog. Launched April 4, the official MEP Blog: Manufacturing Innovations will serve as a focal point for educating U.S. manufacturers, partners and stakeholders on the latest industry trends. “From analyzing economic data to sharing successes of our clients, we hope the Manufacturing Innovations Blog will become a site that inspires conversations about manufacturing in the U.S.,” says Roger Kilmer, director of NIST MEP.
Solar cell technology opportunities for the 21st Century
What are the major technology challenges to future growth in the solar-cell industry? Where are the big-bang-for-the-buck R&D investment opportunities? These and other questions were put to a group of 72 internationally recognized experts in the field at a 2010 special workshop. Their conclusions are summarized in a new NIST publication on Photovoltaic Technologies for the 21st Century. The workshop was led by a steering committee chaired by Roger G. Little, CEO, Spire Corporation, and Robert W. Collins, NEG Endowed Chair of Silicate and Materials Science, University of Toledo, and co-sponsored by NIST.