Synthesis of a phase-pure orthorhombic YBa2Cu3Ox under low oxygen pressure

Abstract Reaction of Y 2 O 3 , BaCo 3 and CuO for 4 h at 800 °C in flowing O 2 with a total pressure of about 2.7 × 10 2  Pa, followed by cooling in O 2 at ambient pressure, has produced phase-pure orthorhombic YBa 2 Cu 3 O x . Keeping the ratio of O 2 to evolved CO 2 above 50 was necessary to ensure phase purity. The resultant powder yielded pressed and inserted pellets with improved superconducting properties.