Ni and Fe dopant sites in YBa2Cu3O7-y identified by XPS

A systematic investigation has been carried out using core level X-ray phot oelectron spectroscopy (XPS) in the Fe- and Ni-doped YBa2Cu3O7-y (YBCO) sys tem by varying the concentration of Cu. The experimental spectra of Ba-Sd, Ba-4d and Y-3d have been utilized to probe the dopant sites. This study ind icates that Fe goes to Cu(1) site and Ni to both Cu(1) and Cu(2) sites. It appears that each metal substituent has a preference for a specific Cu site or combination of sites, which is consistent with the reports available in literature. The present work emphasizes that XPS can be a suitable tool to probe the dopant sites in two inequivalent local sites.