Superconductivity in Hg-substituted BaPb0.75Bi0.25O3

A series of Hg-doped BaPb0.75Bi0.25O3 (BPBO) with a nominal composition of BaPb0.75 − xHgxBi0.25O3 (x=0-0.40 with 0.05 intervals) has been synthesized by solid state reaction. The system shows a lattice parameter expansion and lattice symmetry distortion with Hg doping. Superconducting transition temperature Tc and superconducting volume fraction of the system decrease with Hg doping level in the low doping level region (0⩽x⩽0.25) and are nearly fully suppressed at x=0.25. However, the superconductivity is recovered with further increasing Hg content at x>0.3. The possible mechanisms of the superconductivity in the low doping level region and the recovery of superconductivity in the high doping level region for Hg-doped BPBO system have been discussed.