Category Technology/Electronics

These images show the orbital paths of electrons trapped within a circular region within graphene. In the classical orbit (top image), an electron that travels in a complete circuit has the same physical state as when it started on the path. However, when an applied magnetic field reaches a critical value, (bottom image), an electron completing a circuit has a different physical state its original one. The change is called a Berry phase, and the magnetic field acts as a switch to turn the Berry phase on. The result is that the electron is raised to a higher energy level.
Credit: Christopher Gutiérrez, Daniel Walkup/NIST

The discovery promises new insight into quantum theory and may lead to new quantum electronic devices...

Pure platinum with thin fixed foils of yttrium have been used to create the new nanoalloys that are ten times as effective as pure platinum in fuel cells. Credit: Mia Halleröd Palmgren CC BY 3.0

A new type of nanocatalyst can result in the long-awaited commercial breakthrough for fuel cell cars. Research results from Chalmers University of Technology and Technical University of Denmark show that it is possible to significantly reduce the need for platinum, a precious and rare metal, by creating a nanoalloy using a new production technique. The technology is also well suited for mass production.

“A nano solution is needed to mass-produce resource-efficient catalysts for fuel cells. With our method, only 1/10 as much platinum is needed for the most demanding reactions...

In certain materials, light waves can change their direction of polarization. Credit: TU Wien

The ‘quantized magneto-electric effect’ has been demonstrated for the first time in topological insulators at TU Wien, which is set to open up new and highly accurate methods of measurement. A light wave sent through empty space always oscillates in the same direction. However, certain materials can be used to rotate the direction in which the light is oscillating in a magnetic field, ie ‘magneto-optical’ effect. Rather than switching the direction of the light wave continually,’topological insulators’ do so in quantum steps in clearly defined portions. The extent of these quantum steps depends solely on fundamental physical parameters, such as the fine-structure constant...

1. Nanoporous nickel cathodes for lithium oxygen batteries are ultralight, shown here balanced on flower stamens.
Credit: American Chemical Society
2. Nanoengineered Ultralight and Robust All-Metal Cathode for High-Capacity, Stable Lithium–Oxygen Batteries

Lithium-oxygen systems could someday outperform today’s lithium-ion batteries because of their potential for high energy density. However, a number of important issues, such as their poor electrochemical stability must be addressed before these systems can successfully compete with current rechargeable batteries. Now, in ACS Central Sci

ence, researchers report a new type of cathode, which could make lithium-oxygen batteries a practical option.

Xin-Bo Zhang and colleagues note that most of the problems associated with lithium-oxygen batt...