HIGH-PRESSURE SYNTHESIS AND PROPERTIES OF THE HGBA2CAN-1CUNO2N-6) SUPERCONDUCTORS(2+DELTA (N=1)

High-pressure high temperature synthesis has allowed us to prepare mem bers of the new superconducting mercury cuprates series with n=1-6. Th e variation of the structural and magnetic properties, oxygen content and T-c across the series, which appears to be the richest among the d ifferent superconducting cuprates, will be presented and discussed. T- c and the oxygen content delta increases with n from Hg-1201 (T-c=95K, delta=0.06) to a maximum of 135 K with delta=0.40 for Hg-1223. Struct ural refinement from neutron diffraction data on Hg-1245 showed a furt her decrease of delta=0.30 in the high pressure as prepared compound ( T-c=101K). Tentatives to increase delta by a treatment under 200 bar o f oxygen in Hg-1234, Hg-1245 and Hg-1256 showed instead a loss of oxyg en from the overdoped as prepared samples