The influence of TiO2 additions on the formation and the superconducting properties of the (Bi,Pb)2Sr2Ca2Cu3O10-y phase

In view of the mechanical reinforcement of the Ag sheath of (Bi,Pb)2Sr2Ca2Cu3O10-y tapes by dispersion hardening, the effect of TiO2 additions on the formation of the (Bi,Pb)2Sr2Ca2Cu3O10-y phase is studied. By means of DTA measurements, it is found that the onset temperature of partial melting in the precursor powders is lowered when TiO2 is added. XRD and EDX analysis showed that TiO2 additions result in the formation of SrTiO3 and a decrease of the amount of(Bi,Pb)2Sr2Ca2Cu3O10-y. Lattice parameter calculations as well as Tc determinations also show that Ti substitution in the (Bi,Pb)2Sr2Ca2Cu3O10-y phase, if any, is limited to low values. The interaction occurring between TiO2 and the precursor powders during the formation of the (Bi,Pb)2Sr2Ca2Cu3O10-y phase is described. (author)