Doping Effect on Superconducting Transition of Ba-K-Bi-O System

Chemical doping or substitutions were carried out in both the Ba site and Bi site in Ba-K-Bi-O superconductor. The large single crystals of Ba-K-M-Bi-O (M=Ca, Eu, In and T1) were prepared by using the electrocrystallization method. The resulting crystalline materials were characterized by x-ray photoelectron spectroscopy and magnetic method. The results show that partial substitutions of Ca or Eu in the Ba site suppress T_c more drastically than that of TI in the Bi site. All the present chemical substitutions result in a decrease in T_c.