Preparation of the High-T_c Phase of Bi-Sr-Ca-Cu-O Superconductor

Co-decomposition of mixed nitrates of Bi, Pb, Sr, Ca and Cu around 830°C under low oxygen pressure led to the formation of a high- T c superconducting phase of Bi(Pb)-Sr-Ca-Cu-O with T c (zero) at 107.5 K. A sample prepared by a conventional solid state reaction method under low oxygen pressure also showed the superconducting transition at 107.5 K. X-ray powder diffraction and magnetic susceptibility measurements on these samples revealed the high- T c phase without 80 K or semiconducting phase. The reaction under low oxygen pressure has an effect to lower the temperature with broad ranges to render the high- T c phase of the Bi-Sr-Ca-Cu-O.