Stability studies of Hg implanted YBa2Cu3O6+x

High quality YBa2Cu3O6+x (YBCO) superconducting thin films were implanted w ith the radioactive Hg-197m (T-1/2 = 24 h) isotope to low fluences of 10(13 ) atoms/cm(2) and 60 keV energy. The lattice location and stability of the implanted Hg were studied combining the Perturbed Angular Correlation (PAC) and Emission Channeling (EC) techniques. We show that Hg can be introduced into the YBCO lattice by ion implantation into a unique regular site. The EC data show that Hg is located on a highly symmetric site on the YBCO latt ice, while the PAC data suggests that Hg occupies the Cu(1) site. Annealing studies were performed under vacuum and O-2 atmosphere and show that Hg st arts to diffuse only above 653 K, (C) 1999 Elsevier Science B.V. All rights reserved.