Effect of Cu-site Co, Ni, and Ga substitution on the superconductivity of tetragonal LaCaBaCu3O7-y system

AC susceptibility measurements and normal state magnetism have been carried out on LaBaCaCu3-xMxO7-delta (RE: 1113) system. where M = Co.Ni.Ga with 0 < x < 0.24. Superconducting transition temperature (T-c) of the pristine sa mple, determined from the measurements of both real and imaginary parts of AC susceptibility, decreases with increasing dopant concentration (x) of al l the three cations. T-c depression rate with doping concentration (dT(c)/d x) follows the order Ga > Co > Ni. The normal state DC magnetism implies a localized moment presumably on doped M ions for Co and Ni and an induced ma gnetic moment for Ga-doped system, of nearly 0-5 mu (B), supposedly residin g on Cu ion. (C) 2001 Elsevier Science B.V. All rights reserved.