Thermodynamic Evaluation for the Y₂O₃–BaO–CuO_x System

Abstract

The thermodynamic data for the Yz03-Ba0-CuzO-Cu0 quaternary system were optimized from measured thermodynamic data. A two-sublattice model for ionic solution was used to express the Gibbs free energy of the liquid phase, and a two-sublattice regular solution model was used for the nonstoichiometric Y B a Z C~3 0 6 + 6 superconducting compound. The optimized thermodynamic data were used to calculate the phase diagrams of the CuzO-CuO binary system and the CuOx-YzCuz05 and Cu0,-BaCu02 quasi-binary systems. The results were in good agreement with reported measured data. The liquidus projection and isothermal and vertical sections of the YZ03-Ba0-Cu0, quasi-ternary system were calculated. The effect of oxygen pressure on some reaction temperatures was predicted by calculating them at various oxygen pressures, and the oxygen contents (6 + 8) in YBazCu306+s were calculated at various temperatures and oxygen pressures. The results were compared with experimental data. [

Phase Diagram Studies in the System Tl2O3–BaO–CaO–CuO–Ag

“…The most significant aspect is the fact that Tl 2 O 3 decomposes at about 780°C, forming Tl 2 O and oxygen. In addition, it is emphasized that a liquid phase occurs in the system BaO-CuO at about 926°C in oxygen atmosphere (906°C in air) 8 that almost corresponds with the preparation temperature of 1223 ceramics. 11 The system Tl 2 O 3 -BaO-CuO has been studied in Ref.…”

“…The systems Tl-O, 6 BaO-CuO, 7,8 CaO-CuO, 9 and Tl 2 O 3 -CuO 10 have been studied in detail. The most significant aspect is the fact that Tl 2 O 3 decomposes at about 780°C, forming Tl 2 O and oxygen.…”

Construction of the Quasi‐ternary Phase Diagram in the NdO1.5‐BaO‐CuOx System in an Air Atmosphere: Part I, Equilibrium Tie Lines in the Nd1+xBa2−xCu3O6+δ Solid Solution and Liquid Region

“…1(a) (tie lines are only schematic). [16][17][18][19][20][21] Therefore, any liquid compositions coexist with only one solid composition of the Y123 phase. On the other hand, in the neodymium system of Fig.…”

Grain boundaries in high temperature superconducting ceramics

“…The knowledge of the stable and metastable equilibrium phases at high temperatures, especially in the YBCO primary solidification region, has proved essential to determine the effective conditions for both single crystal growth and YBCO peritectic crystallization. Until now, the solid-state equilibrium, the melting temperatures, the extension of the primary crystallization fields of the solid phases and their dependence on oxygen pressure have been extensively studied [48], [49], [50], [51]. A review of the chemical principles of the preparation of metal-oxide superconductors can be found elsewhere [52].…”