Thermodynamic stability field of the 123 and 124 phases in the Y2O3-BaO-Cu-O system

Zhigang Zhou, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The partial molar entropy of solution of oxygen in YBa2Cu3Ox, AYo, has been computed using equilibrium data and the recently measured partial molar enthalpy of oxygen. While Ah0 is independent of oxygen content (6 < x < 7), As0depends on x. The p0l, T location of phase equilibrium between the 123 and 124 superconducting phases is calculated. The standard free energies of interactions of the superconducting phases with carbon dioxide (C02 and water vapor (H20) have been assessed. The free energies of carbonation of the fully oxidized 123 and 124 phases are —323 ± 22 kJ mol-1 and —291 ± 32 kJ mol-1, respectively. The free energies of hydration of the 123 and 124 are —397 ± 22 kJ mol-1 and —469 ± 32 kJ mol-1, respectively. These large exothermic values show that degradation of these superconductors at ambient conditions is thermodynamically favorable.

Original languageEnglish (US)
Pages (from-to)3023-3031
Number of pages9
JournalJournal of Materials Research
Volume8
Issue number12
DOIs
StatePublished - Dec 1993
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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