SYNTHESIS, CRYSTAL-STRUCTURE AND PROPERTIES OF HG2BA2(Y,CA)CU2O8-DELTA - THE FIRST CUPRATE SUPERCONDUCTOR CONTAINING A DOUBLE MERCURY OXYGEN LAYER by Radaelli, P, Marezio, M, Tholence, J, Debrion, S, Loureiro, S, Santoro, A, Huang, Q, Capponi, J, Alariofranco, M, Chaillout, C