Effect of atmosphere on the formation of low T c and high T c phases in Bi-Pb-Sr-Ca-Cu-O superconductors

Abstract
Two kinds of sintering atmosphere, N2 and air, were used to study the effect of atmosphere on the formation of the low Tc phase and the high Tc phase. The annealing temperatures were 810 °C in N2 and 850 °C in air. The resistivity measurements and the x‐ray diffraction analysis showed that while the fraction of the high Tc phase continued to increase with sintering times in air, it did not increase in any appreciable amount even after 264 h of sintering in N2 atmosphere. Compared with air, N2 atmosphere enhanced the formation of the low Tc phase and inhibited the formation of the high Tc phase.