Enhancement of T-c in HgBa2Ca2Cu3O8+delta by fluorination - art. no. 064511

A 4 K increase of T-c in Hg-1223 was achieved by the exchange with fluorine of the extra oxygen located in (HgOdelta) layer. Fluorination of the initi ally reduced Hg-1223 samples with T-c similar or equal to 100 K by XeF2 res ults in the increase of T-c up to 138 K while treatment in oxygen flow caus es the enhancement of T-c not higher than up to 134 K. From x-ray and neutr on diffraction data we conclude that shortening of the in-plane Cu-O distan ces without significant (CuO2) layers buckling in fluorinated Hg-1223 seems to be thr main structural factor responsible for the enhancement of T-c.