Synthesis and structural characterization of the 127 K HgBa2CaCu2O6.22 superconductor. Tc variations upon different atmosphere annealings

S. M. Loureiro, E. V. Antipov, J. L. Tholence, J. J. Capponi, O. Chmaissem, Q. Huang, M. Marezio

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98 Citations (Scopus)

Abstract

The synthesis of the HgBa2CaCu2O6+δ (Hg-1212) superconductor under various experimental conditions in sealed silica tubes is reported. Optimization of synthesis conditions allowed the preparation of bulk superconducting Hg-1212 with Tc onset at 127 K and lattice parameters a=3.858 A ̊, c=12.68 A ̊. The neutron powder diffraction analysis yielded δ=0.22(4). As a result of different atmosphere annealings a relationship between the decrease of Tc and the increase of the lattice parameter a is deduced. A 300°C/10 h treatment in 99% N2/1% O2 reduces Tc to 123 K and increases the a parameter to 3.862 Å. An additional 10 h reduction in a 100% N2 flow lowers Tc to 98 K while a increases to 3.865 Å. Subsequent oxidation at 300°C for 10 h in O2 flow restores the lattice parameters and Tc onset to their original values. The Tc dependence on annealing conditions is shown to be reversible.

Original languageEnglish
Pages (from-to)253-264
Number of pages12
JournalPhysica C: Superconductivity and its Applications
Volume217
Issue number3-4
DOIs
Publication statusPublished - 20 Nov 1993
Externally publishedYes

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