Category Physics

Polyhedral representation of the crystal structure of fluoride-phosphate of vanadium and potassium. The yellow denotes a three-dimensional channel system, which provides rapid transport of Li+ ions. Credit: Stanislav Fedotov

A cathode material for li-ion batteries with a very high charge rate – down to 90s – has been created, retaining more than 75% of an initial capacity. The discovery may stipulate the development of batteries where expensive lithium could be replaced with cheaper potassium.

Nowadays Li-ion batteries power a wide range of electronic devices: mobile phones, tablets, laptops. They became popular in 90s and subsequently ousted widespread nickel-metal hydride batteries. However, their capacity may drop when temperature falls below 0...

The algorithm Melvin found out that the most simple realization can be asymmetric and therefore counterintuitive. Credit: Copyright: Robert Fickler, Universität Wien

Algorithm does not work intuitive – just as quantum physics. Quantum physicist Mario Krenn et al have developed an algorithm which designs new useful quantum experiments. As the computer does not rely on human intuition, it finds novel unfamiliar solutions. The idea was developed when the physicists wanted to create new quantum states in the laboratory, but were unable to conceive of methods to do so. “After many unsuccessful attempts to come up with an experimental implementation, we came to the conclusion that our intuition about these phenomena seems to be wrong...

A 2-mm-diameter ethanol droplet impacts on a hot surface. The corresponding videos with TIR images showing the droplet height are below. Credit: Shirota, et al. ©2016 American Physical Society

Leidenfrost effect occurs when water droplets levitate and skid around on top of a very hot surface, rather than immediately evaporating like they do at temperatures that are not quite as hot. The effect occurs because the bottom of the droplet rapidly vaporizes as it approaches the hot surface, causing the droplet to levitate on top of its own vapor. It has industrial cooling applications.

Now researchers have filmed the 1st videos of the tiny (<100 nm) levitation space between the hot surface and the impacting liquid droplet, in this case not of water but ethanol and fluorinated heptane...

A patented breakthrough by researchers at Technion-Israel Institute of Technology improves efficiency of organic photovoltaic cells by 50%, and could someday provide a huge boost for the viability of solar power as a major source of energy.

Organic photovoltaic cells convert solar energy into electric power through organic molecules. One of their advantages over “traditional” solar cells made of silicon is that they can be mounted on lightweight, flexible, and easy-to-replace sheets, which can be spread on roofs and buildings like wallpaper, converting solar energy into electrical current. In the future, they could also be used to provide a cost-efficient and reliable source of electricity in isolated regions...