A NEW MERCURY-BASED SUPERCONDUCTOR - (HG, CR)SR2CUOY

A new mercury-based cuprate superconductor, (Hg1-xCrx)Sr2CuOy (0 less- than-or-equal-to x less-than-or-equal-to 0.8),having T(c) of 58 K (x=0 .3) has been synthesized. While a chromium-free sample (x=0) was multi -phased and the superconducting volume fraction was less than 1%, samp les for x=0.3 and 0.4 were of nearly single phase and their supercondu cting shielding volume fraction reached 100% of perfect diamagnetism. X-ray diffraction analysis revealed, that its crystal symmetry was tet ragonal with lattice parameters a0 = 3.840-3.8 54 angstrom and c0 = 8. 639-8.705 angstrom which slightly varied with x. The observed co value , corresponding to the interlayer distance of superconducting CuO2 pla nes, was found to be the shortest among all the known mercury-based '' 12 (n-1) n'' superconductors. Compared to the barium-containing compou nds, the present barium-free materials have been found to be insensiti ve to the ambient air atmosphere during the synthesis and also to be q uite stable after storage in air.