T_c=113 K Bi-Based Superconductor Prepared by Doping Fluorine

Abstract

A new method for preparing a Bi-based superconductor with T c =113 K and T c,end =106 K is reported. Starting powders including a small amount of fluoride are heated in air. The final heating temperature is 860°C, which is lower by about 20°C as compared to the case without doping fluorines. During the heating process most fluorines are released from the crystal, while the (243) phase increases in volume at the cost of the (232) phase. High-resolution transmission electron microscopy (HRTEM) reveals that a frequent intergrowth occurs in the crystal.