Oxygen annealing and the related thermodynamics in HgBa2CuO4+δ

Q. Xiong, Y. Y. Xue, F. Chen, Y. Cao, Y. Y. Sun, L. M. Liu, A. J. Jacobson, C. W. Chu

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30 Citations (Scopus)


Several well-characterized HgBa2CuO4+δ samples were annealed under various conditions. Above 300°C and at various oxygen partial pressures, both reversible oxygen intake/release and irreversible Hg-loss take place with different time constants. By choosing the proper annealing temperature Ta, oxygen pressure P(O2) and annealing time t, the Hg-loss effects were negligible and the bulk superconducting transition temperature Tc was reversibly changed with δ from 0 K on the underdoped side (an insulator) through a peak of 97 K, then down to ∼ 20 K on the overdoped side. The measured 3D variation of Tc vs. (1/Ta, ln P(O2)) appears as a parabolic surface with iso-Tc segments projected on a 2D 1/Ta-ln P(O2) plane as straight lines. The slope [∂ ln P(O2)/∂(1/Ta)]Tc of the projections corresponds to the oxidation enthalpy ΔH, and the derivative (∂ ln P(O2)/∂Tc)Ta which is a measure of the Tc variation with the oxygen partial pressure used in the annealing, is related to the defect-interactions and the Tc-δ correlation. The data for YBa2Cu3O7-δ, Bi2Sr2CaCu2O8+δ, and HgBa2CuO4+δ are compared.

Original languageEnglish
Pages (from-to)233-242
Number of pages10
JournalPhysica C: Superconductivity and its applications
Issue number3-4
Publication statusPublished - 1994 Oct 1

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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