Study of bulk and single crystal YBa2-xSrxCu3O7- delta superconducting materials

A detailed study of the substitution of Sr for Ba in the system YBa2-xSrxCu3O7- delta has been carried out, for both bulk and single-crystal material. Successful substitution, in bulk samples, of up to 80% (x=1.6) was accomplished. This substitution is seen to have an adverse progressive effect on the value of Tc. All bulk Sr-substituted compounds were superconducting with values of Tc of at least 73 K. The 100% Sr-substituted sample YSr2Cu3O7- delta has been observed, but only in very small amounts. Single crystals of Y(Ba, Sr)2Cu3O7- delta with Sr/Ba substitution of up to 30% (x=0.6) have also been synthesized and characterized by XRD and SEM.