Ba2 Cu Hg O4.27 Pissas M, Billon B, Charalambous M, Chaussy J, LeFloch S, Bordet P, Capponi J Superconductivity: Science and Technology 10 (1997) 598-604 Single-crystal growth and characterization of the superconductor HgBa2CuO4+d _cod_database_code 1008820 _database_code_amcsd 0016689 3.8792 3.8792 9.5117 90 90 90 P4/mmm atom x y z occ Hg1 0 0 0 Cu1 0 0 .5 Ba1 .5 .5 .2991 O1 0 0 .212 O2 .5 0 .5 O3 .5 .5 0 .27