A fluorination of the reduced HgBa2CuO4+δ(Hg-1201) with Tc=61K resulted first in an increase in Tc up to 97 K and then in a decrease and even a suppression of superconductivity due to overdoping. Neutron powder refinements performed on fluorinated HgBa2CuO4Fδ showed twice the amount of extra fluorine in comparison with those for the oxygenated -1201 phases with close Tc. This supports the ionic model of doping in Hg-1201: two holes per oxygen and one hole per fluorine. The apical distances in Hg-1201 depend on the number of dopant atoms rather than on their charge. The exchange of extra oxygen for a double amount of fluorine shortens the apical Cu-O distances, while the in-plane distances and Tc do not vary.
ASJC Scopus subject areas
- Physics and Astronomy(all)