Very high Tc superconductors in hydroxyl and fluoride-containing Bi2Sr2Ca2Cu3Oy ceramics systems

Experimental data of ceramic superconductors for maximum Tc, up to 135 K, are reported with regard to fluoride- and hydroxyl-containing Bi2Sr2Ca2Cu3Oy systems. Both magnetic and resistivity measurements confirmed a maximum critical superconductive temperature at 135 K, distinctly higher than the previous record value at 125 K observed in Tl2Ba2Ca2Cu3O10 ceramics. This increase in Tc is presumably associated with superconductive structural phase transition or phase equilibrium for [CuO6] octahedra, occupied by hydroxyl or fluorine ions in oxygen vacancies.