Comparative study to enhance the phase formation of Tl-based superconductor with three CuO layers

Abstract

Characteristics of the “1223” phase in the (Tl, Bi, Pb)SrCaCuO superconductor system have been enhanced using an over-stoichiometric “1234” precursor (Tl 0.64Pb 0.2Bi 0.16)Sr 2Ca 3Cu 4O y . The quality of the 1223 phase heavily depends on the synthetic condition of the 1234 precursor. The precursor synthesized from Sr 2Ca 2Cu 3O y yields the most “1223” phase after 920°C sintering for 10 h, whereas a remarkable amount of the “1212” phase containing two CuO layers was accompanied in other synthetic courses. Although some solid solution impurities are observed, they are not inevitable with a Ca-rich composition. Quality of the superconducting phase was examined by X-ray diffraction, resistivity and magnetization measurements.