Stability of oxygen in HgO added bulk Y-Ba-Cu-O superconductor

The role of HgO as internal source of oxygen in bulk Y-Ba-Cu-O superconductor is studied in detail. Sample with 1.0 wt% HgO, quenched directly to room temperature from 900 degreesC, depicts metallic resistivity pattern and a T-c0 of similar to 86 K. The pure sample, however, depicts non-metallic resistivity pattern and T-c0<77 K when quenched from 900<degrees>C. The thermogravimetric analysis (TGA) reveals two step oxygen loss over a temperature range 600-950 degreesC in both the cases. However, the loss kinetics of oxygen is slower in the case of HgO added sample. The activation barriers E for the two-step oxygen out-diffusion process turn out to be 1.15 eV and 0.29 eV in the case of pure sample and 1.74 eV and 0.86 eV in the case of HgO added sample. The oxygen released by HgO within the bulk Y-Ba-Cu-O is, therefore, more strongly bonded with the lattice.