Abstract
Bulk superconducting samples of nearly phase-pure HgBa2Ca2Cu3O8+δ (hereafter denoted as Hg-1223) were prepared by a solid-state reaction of stoichiometric quantities of HgO, BaO, CaO, and CuO in a single step. The starting mixtures were ground, pressed into a pellet, sealed in a quartz tube, and heated to 840-860°C. The "as-synthesized" Hg-1223 samples had a Tc of 110-112 K, as defined by the onset of diamagnetism. The crystal symmetry was found to be tetragonal with a space group of P4/ mmm, and lattice parameters a=3.852(1) A ̊ and c=15.830(1) A ̊, similar to the values for TlBa2Ca2Cu3O9-δ. Finely ground powders were stable upon exposure to ambient air for a period of ≈4 days. On annealing in 1 atm oxygen at 300°C for 6 h, these samples gained weight (corresponding to ≈0.066-0.075 oxygen atoms per formula unit) and displayed sharp superconducting transitions up to 134.5 K. Using this procedure, high-quality Hg-1223 samples can be easily synthesized.
| Original language | English |
|---|---|
| Pages (from-to) | 7-12 |
| Number of pages | 6 |
| Journal | Physica C: Superconductivity and its Applications |
| Volume | 222 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - Mar 10 1994 |
Funding
The author thanks J. Brynestad for encouragement and helpful discussions, E.D. Specht for assistance with the X-ray measurements, and P. Martin for technical assistance with the AC susceptibility measurements. The research was sponsored by the Division of Materials Sciences, Office of Basic Energy Sciences, US Department of Energy and technology development was funded by the US Department of Energy Office of Advanced Utility Concept-Superconductor Technology Program, both under contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc. This work was also supported by the Oak Ridge National Laboratory Postdoctoral Research Program, administered jointly by the Oak Ridge Institute for Science and Education and ORNL.