Items Tagged With Materials Science

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a prototype nanoscale electronic switch that works like lightning—except for the speed. Their proof-of-concept experiments reported last week* demonstrate that nanoscale electrical switches can be built from self-assembled layers of organic molecules on silver wires. Potential applications range from a replacement technology for magnetic data storage to integrated circuit memory devices.

Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory have discovered that nanocrystals of germanium embedded in silica glass don’t melt until the temperature rises almost 200 K above the melting temperature of germanium in bulk. What’s even more surprising, these melted nanocrystals have to be cooled more than 200 K below the bulk melting point before they resolidify. Such a large and nearly symmetrical “hysteresis”—the divergence of melting and freezing temperatures above and below the bulk melting point—has never before been observed for embedded nanoparticles.

It has long been known that it is possible to confine electrons or atoms in atomic structures in the same way as sheep can be shut in a pen. Physicists at the Max Planck Institute for Microstructure Physics in Halle have now discovered a strange thing: if the atomic fences have the right shape and the substrate, temperature and other parameters are adjusted appropriately, then randomly vapour-deposited atoms arrange themselves in regular structures within the circular fencing—as if they were sheep arranging themselves neatly in a pen (Physical Review Letters, 2 November 2006, doi: 10.1103/PhysRevLett.97.186403).