Abstract
Superconductivity in aromatic hydrocarbons doped with potassium (K) such as [picene (PCN)] and [phenanthrene (PHN)] is found for only armchair-type polycyclic aromatic hydrocarbon. In this paper the thermodynamics of the reaction processes of PHN or anthracene (AN, zigzag type) with K was studied using differential scanning calorimetry and x-ray diffraction. We show that PHN decomposes during the reaction, triggered by hydrogen abstraction, to give metal hydride KH and unknown amorphous. No stable doped phases exist in with stoichiometries of . However, in the case of AN, a stable doped phase forms. We claim that PHN, which has been reported to be energetically more stable in the ground state than AN by first principle calculations, is unstable upon doping. We also suggest that the superconductivity in is due to the misinterpretation of experimental data, which actually arises from ferromagnetic impurities. We have never detected the superconductivity above 2 K in these compounds. The superconductivity in both and is concluded to be highly questionable.
6 More- Received 30 May 2015
DOI:https://doi.org/10.1103/PhysRevB.92.014502
©2015 American Physical Society