Picene

Like the carbon-60 crystals, superconductivity in picene is believed to be related to p-electrons. ❋ Unknown (2010)

In particular, they don't know whether the potassium atoms lie within the picene planes or between the planes - although they believe the former to be more likely. ❋ Unknown (2010)

But according to Prassides, the superconductivity comes as a surprise because picene molecules arrange themselves in 2D planes much like graphite. ❋ Unknown (2010)

Now, Ryoji Mitsuhashi and colleagues at Okayama University in Japan have found that crystals made from the hydrocarbon picene and potassium atoms are superconductors at temperatures up to 18K. ❋ Unknown (2010)

The team begin with an ultrapure picene crystal that is then heated in the presence of potassium for several days. ❋ Unknown (2010)

Only one sample - containing 3.1 rubidium atoms per picene molecule - was superconducting with a Tc of about 7K. ❋ Unknown (2010)

The team studied crystals with a range of potassium concentrations from one potassium atom per picene molecule to 5.1 per molecule. ❋ Unknown (2010)

It turns out, however, that by pure coincidence, picene has two p-electron states with the same energy. ❋ Unknown (2010)

(PhysOrg. com) -- Scientists from Okayama University in Japan have discovered that the hydrocarbon picene can be made to superconduct when potassium atoms are interspersed with the picene crystals and the doped picene is cooled. ❋ Unknown (2010)

Professor Kubozono said picene is the first example of a hydrocarbon superconductor, although scientists have been able to create superconductors of the carbon compound fullerene (C60) doped with potassium. ❋ Unknown (2010)

The researchers cooked picene with potassium, which forced the alkali atoms between the layers and improved its conductivity in planes parallel to the layers. ❋ Unknown (2010)

The researchers are now trying other metals with picene, including cesium and sodium, and are testing other hydrocarbons for superconductivity. ❋ Unknown (2010)

It is usually a semiconductor, but the researchers, led by Yoshihiro Kubozono, found that when synthesized picene is doped ❋ Unknown (2010)

Photographs show pristine picene (top; white) and Kxpicene (bottom; black). ❋ Unknown (2010)

The picene molecule resembles five benzene rings joined in a staggered line, and is a flat molecule that stacks into layers to form crystals. ❋ Unknown (2010)

Molecular structure, crystal structure and physical appearance of picene. ❋ Unknown (2010)

More information: Superconductivity in alkali-metal-doped picene, Ryoji Mitsuhashi et al., ❋ Unknown (2010)

Researchers in Japan have made the first superconducting hydrocarbon material by adding potassium atoms to picene (C ❋ Unknown (2010)