earticle

영어

We report the solid-liquid phase equilibria on the GdBa2Cu3O7-δ (GdBCO) stability phase diagram in low oxygen pressures (PO2) ranging from 1 to 100 mTorr. On the basis of the GdBCO stability phase diagram experimentally determined in low oxygen pressures, the isothermal sections of three different phase fields on log PO2 vs. 1/T diagram were schematically constructed within the Gd2O3-Ba2CuOy-Cu2O ternary system, and the solid-liquid phase equilibria in each phase field were described. The invariant points on the phase boundaries include the following three reactions; a pseudobinary peritectic reaction of GdBCO ↔ Gd2O3 + liquid (L1), a ternary peritectic reaction of GdBCO ↔ Gd2O3 + GdBa6Cu3Oy + liquid (L2), and a monotectic reaction of L1 ↔ GdBa6Cu3Oy +L2. A conspicuous feature of the solid-liquid phase equilibria in low PO2 regime (1 - 100 mTorr) is that the GdBCO phase is decomposed into Gd2O3 + L1 or Gd2O3 + GdBa6Cu3Oy + L2 rather than Gd2BaCuO5 + L well-known in high PO2 like air.