Magnetic susceptibility and AC loss in HgPb1223 ceramic superconductors

Compounds of the series Hg_1-xPb_xBa₂ Ca₂Cu₃O_y (x=0.1 and 0.2) were synthesized directly from the metal oxides without using a precursor. AC susceptibilities and DC magnetizations were measured using a SQUID magnetometer and a PPMS susceptometer. The superconducting volume fractions were estimated from the temperature dependence of the Meissner magnetization and showed that Pb-substitution of Hg-site enhanced the volume fraction without sacrificing the critical temperatures of 134 K in both samples. Critical current densities estimated from the magnetization are compared in both samples. The peak value of the imaginary part of the AC susceptibilities λ" of less than 3/4π indicates the reversible fluxoid motions in a pinning potential in HgPb1223. Reversible motion factor r, the Campbell penetration depth λ\´₀ and AC losses were estimated from AC susceptibilities and compared with the Matsushita formula based on the Campbell model