MERCURY-ENHANCED HIGH-TC IN THE BI(PB)-SR-CA-CU-O SYSTEM

This short communication reports an onset T(c) as high as 135 K and a T(c0) (zero resistivity) of 114 K in a Bi1.7Pb0.3Sr2-xHgxCa2Cu3Oy comp osition. Mercury does not seem to be incorporated in the lattice. It a ppears probable that mercury enhances the oxidation state of copper in the CuO2 layers and thus raises the T(c). Very interestingly, the XRD spectra of these specimens show the presence of only one phase, that is, the 2212 phase of the Bi-system. Highest value of T(c0) (114 K) wa s consistently found for Hg=0.3, even when the entire series of specim ens was prepared four times under identical conditions. The studies hi nt at the possibilities of obtaining T(c) values higher than the stand ard assigned T(c) values to various oxide superconductors.