Abstract
Thermogravimetric measurements of the equilibrium oxygen partial pressure ( p(O 2)) as a function of temperature and oxygen content have been made on GdBa 2Cu 3O y (Gd123) within the range 3×10 −4 atm≤ p(O 2)≤1 atm and 450°C≤ T≤800°C. The partial molar entropy Δ S ̄ (O 2) and enthalpy Δ H ̄ (O 2) of solution of oxygen in Gd123 are evaluated and discussed. The p(O 2) data on Gd123 are compared with measurements performed on NdBa 2Cu 3O y (Nd123) at 800°C and literature data for YBa 2Cu 3O y (Y123) at 600°C and 800°C. The orthorhombic/tetragonal transition temperature ( T O/T) for Gd123 and Nd123 as a function of the oxygen partial pressure (1×10 −3 atm≤ p(O 2)≤1 atm) has been determined by high temperature X-ray diffraction (HTXRD). The oxygen content values for the O/T transition ( y O/T) at several p(O 2) values for Gd123 and Nd123 have been determined by means of thermogravimetric measurements. The obtained data in the y– T diagram supports the applicability of the quasichemical approximation in describing the O/T transition of Gd123 and Nd123 compounds. The effect of the R atom (R=Y, Gd, Nd) ionic size on the oxygen stoichiometry and phase stability of R123 compounds at high temperature is discussed, and a possible explanation is proposed which accounts for the lattice mismatch between Ba–O and CuO 2 layers.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
