Synthesis of Melted Yttrium Barium Copper Oxide-0.325Ag Superconductors Contained in a Solid Silver Cladding at Reduced Oxygen Partial Pressures

This paper presents a study on the feasibility of concurrent synthesis and melt-processing of Yttrium Barium Copper Oxide-0.325 Ag (Y123-Ag) superconductor by thermo-mechanical processing of the silver-clad precursor containing BaCuO_2.5 at reduced oxygen partial pressures. At 950-955°C the melted Y123-Ag superconductor was contained in a solid silver cladding which melted at 960-965°C. After 15 min at 950-965°C and oxygen partial pressures of 0.28 and 0.55 kPa, melted orthorhombic Y123-Ag formed. On extending the heat-treatment from 15 to 30 min, the orthorhombic Y123-Ag changed to tetragonal Y123-Ag which was supported directly by a series of rapid-heat, soak, and rapid-cool experiments at 950°C (P_O2 = 0.28 kPa), and thus direct formation of orthorhombic Y123-Ag from BaCuO _2.5. The highest critical current densities, J_c (transport) at 77 K and J_c (magnetization) estimated from the magnetization hysteresis loop were 4.0 × 10³ and 1.2 × 10⁵ A/cm², respectively.