Properties of Pb-Stabilized Bi-Oxide Superconductors
The initial magnetization curve of B1.5Pb0.5Sr2Ca2Cu3Ox superconductor with the Tc of 105 K was measured. The lower critical field, Hcl, was 6 Oe at 77 K, which was much smaller than that of YBa2Cu3O7-y (52 Oe). The volume fraction of the 105 K phase was estimated to be about 80 %.
Grinding the powder in an attrition mill resulted in a slight increase in Tc, although the densification of the sintered body did not ocurr. By hot-pressing at a pressure of 39 MPa at 800 °C in vacuum of 5 x 10-5 Torr for 2 h, the bulk density of the hot-pressed sample reached 6.21 g/cm3 , which was higher than 95 % of the theoretical density, and the Tc was 72 K. The grains were oriented with the c-axis along the pressing axis. After annealing at 835 °C in air for 40 h, the Tc was improved to be 108 K and the critical current density at 77 K was found to be 731 A/cm2.
KeywordsBulk Density Critical Current Density Theoretical Density Pressing Axis Sintered Body
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- M.A.Subramanian, C.C.Torardi, J.C.Calabrese, J.Gopalakrishnan, K.J.Morrissey, T.R.Askew, R.B.Flippen, U.Chowdhry and A.W.Sleight: Nature 239, 1015(1988).Google Scholar