ROLE OF BARIUM ADDITION ON THE PROPERTIES OF BISMUTH-BASED SUPERCONDUCTORS

The effect of the addition of barium on the zero resistance temperature, T(c), of Bi1.6Pb0.4Sr1.6Ca2BaxCu4Oy, x = 0.4, 0.5, 0.6, 0.8 and 1.6 was studied. The added barium had the effect of raising T(c) to a higher temperature region, although too much barium gave rise to semiconducting resistance temperature behaviour. X-ray diffraction analysis showed that as the barium concentration, x, increased from 0.4 to 0.8, a decrease in the low T(c) phase and peaks due to CuO and BaBiO3 appeared, whereas an increase in the peaks due to the high T(c) phase and BaCUO2 were seen. Critical current densities were also measured in zero field at 77 K.