Synthesis of High Temperature Superconductors HgBa 2 CuO 4+y and HgBa 2 Ca 2 Cu 3 O 8+y

High critical temperature superconductors of mercury-based system were synthesized under high pressure and high temperature. The resistance and ac magnetic susceptibility measurements for sample prepared at 25 kbar and 850°C for 1.5 h show that the sample without any added treatment was a mixture of Hg-1201 and Hg-1223. The Tc values of Hg-1223 phase and Hg-1201 phase are 132 and 98 K, respectively.