Abstract
Substitution of Tl for Hg was performed in the Hg based 1223 phase HgBa2Ca2Cu3O8 + δ (Tc = 135 K), resulting in an increase of the superconducting transition temperature to 138 K for samples with a nominal composition of Hg0.8Tl0.2Ba2Ca2Cu3O8 + δ. The crystal structure of this solid solution has been investigated by neutron powder diffraction techniques at room temperature and at 10 K. The compound has the same crystal as Hg-1223 with the space group symmetry P4/mmm and lattice parameters a = 3.8489(1), c = 15.816(1) A ̊. Rietveld analysis results indicate that Hg is partially replaced by Tl, and the oxygen content, δ, is 0.33. The lattice-parameter changes resulting from the Tl substitution are too small to account for the Tc change by mimicking the effect of pressure. No phase transition occurs down to 10 K.
| Original language | English |
|---|---|
| Pages (from-to) | 201-206 |
| Number of pages | 6 |
| Journal | Physica C: Superconductivity and its Applications |
| Volume | 243 |
| Issue number | 3-4 |
| DOIs | |
| State | Published - Mar 1 1995 |
Funding
We thank J.A. Fernandez-Baca, M. Yethiraj, R.M. Nicklow and H.A. Mook for stimulating conversations. This research was supported in part by the Division of Materials Sciences, U.S. Department of Energy under Contract No. DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc. and by Midwest Superconductivity, Inc.