BULK SUPERCONDUCTORS WITH ZERO RESISTANCE AT 111 K IN Bi-Sr-Ca-Cu-O SYSTEM AND THE SYNTHESIS

I. INTRODUCTION The new rare-earth-free Bi-Sr-Ca-Cu-O superconducting material is possessed of higher critical temperature, stable properties and cheaper price with fine prospects. Since the new system was first reported by H, Maeda et al. in Jan. 1988, much research works on the sys- tem has been undertaken~|2-5|. After the sharp drop of resistivity at 110 K a bulk