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-degrees-C for 1.5 h show that the sample without any adde
d treatment was a mixture of Hg-1201 and Hg-1223. The T(c) values of H
g-1223 phase and Hg-1201 phase are 132 and 98 K, respectively.