Synthesis, structure and transport properties in the superconducting Tl_1-xBi_xSr₂CuO_5±δ system

Single phase samples of Tl_1-xBi_xSr₂CuO_5±δ for 0.2≤x≤0.5 have been prepared under various synthetic conditions and characterized by X-ray diffraction, electrical resistivity, magnetic susceptibility and TGA measurements. Superconductivity with a T^onset_c at 45 K has been found in samples of 0.2≤x≤0.3 which are quenched from 850°C into liquid nitrogen and then annealed at 400°C for 1 h in air. In the range 0.2≤x≤0.5, both semiconducting and metallic phases can be prepared. In general, samples quenched from 850°C to liquid nitrogen temperature are semiconducting; semiconducting samples annealed in air or O₂ for longer periods and at higher temperatures yield metallic phases. The effect of various preparation conditions on the structural and physical properties of Tl_1-xBi_xSr₂CuO_5±δ are discussed.