• Gibbs’ energy of formation of YBa2Cu3O7-x (tetragonal)

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    • Keywords

       

      Gibbs’ energy; oxygen partial pressure; free energy; stability

    • Abstract

       

      The high temperature ceramic oxide superconductor YBa2Cu3O7-x (1–2–3 compound) is generally synthesized in an oxygen-rich environment. Hence any method for determining its thermodynamic stability should operate at a high oxygen partial pressure. A solid-state cell incorporating CaF2 as the electrolyte and functioning under pure oxygen at a pressure of 1·01 × 105 Pa has been employed for the determination of the Gibbs’ energy of formation of the 1–2–3 compound. The configuration of the galvanic cell can be represented by: Pt, O2, YBa2Cu3O7−x, Y2BaCuO5, CuO, BaF2/CaF2/BaF2, BaZrO3, ZrO2, O2, Pt. Using the values of the standard Gibbs’ energy of formation of the compounds BaZrO3 and Y2BaCuO5 from the literature, the Gibbs’ energy of formation of the 1–2–3 compound from the constituent binary oxides has been computed at different temperatures. The value ofx at each temperature is determined by the oxygen partial pressure. At 1023 K for O content of 6·5 the Gibbs’ energy of formation of the 1–2–3 compound is −261·7 kJ mol−1.

    • Author Affiliations

       

      A M Azad1 O M Sreedharan1 K T Jacob1 2

      1. Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102, India
      2. Department of Metallurgy, Indian Institute of Science, Bangalore - 560 012, India
    • Dates

       
  • Bulletin of Materials Science | News

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