EFFECT OF FLUORINE TREATMENT OF YBa₂Cu₃O_{7 - /}/x

Effects of fluorine treatment of YBa//2Cu//3O//7// minus //x were investigated. The T//c was increased about 2 degrees by freon treatment at 400 degree C. The T//c, however, was dropped about 2 degrees in a day of exposure in air at room temperature into similar values for the sample without freon treatment. The fluorite-doping of YBa//2Cu//3O//7// minus //x have also been examined, but did not yield any higher T//c phases. Since the doped fluorides were hydrolyzed by H//2O contained in air at high temperature, the amounts of the fluorine in Y-Ba-Cu-O phase were gradually decreased during reaction, sintering, and/or annealing, and would become very small. 9 Refs.