Chemical Doping and Physical Properties of Superconducting Perovskites

The effects of chemical doping of the high temperature superconducting system ABa2Cu3O7-d with Sc, Ti and V on transport and magnetic properties are presented. The various compounds with A=Y,Sc,Eu,Tm,Ho,Gd,Yb,Nd were prepared by different methods and identified by powder X-ray diffraction and electron microprobe analysis. The partial substitution with Sc, Ti, V leads to samples with similar Tc-values as the undoped ones but broader transition width. The sharpest transition, however, was observed for the YBa2Cu3O7-d compound doped with Ag and F. The partial substitution of Tm and Ho by Sc, Ti and V has only a small influence on the transition temperatures. Vibrational spectra of some of these compounds are also presented in the Cu-O stretching mode region. Furthermore, due to actuality we present physical properties of the superconducting compound BiCaSrCu2Ox showing a Tc-value of about 106 K.