A reproducible synthesis method for superconducting HgBa2Ca2Cu3O8+δ (Hg-1223) has been developed, using sealed silica tubes and a CoO/Co3O4 mixture as oxygen getter to achieve a controlled partial pressure of oxygen. Samples containing more than 95% of Hg-1223 were prepared with this technique. A significant range of substitution of Cu for Hg was revealed by EDS analysis in samples synthesized at 900°C. After post-anneal in oxygen the lattice parameters were calculated from XRD data and Tc was determined to be 135 K, by susceptibility methods. We suggest that a high synthesis temperature and a low partial pressure of mercury promote substitution in the Hg-1223 phase.
- Substitution of copper for mercury
- Synthesis of Hg-1223