Synthesis of yttrium barium copper oxide-0.325Ag superconductors via intermediate precursor with overall composition Y:Ba:Cu:0=l:2:3:Y, Y>7 produced by high-energy attrition milling

Abstract

A highly homogeneous composite precursor containing nano-scale particles was synthesized from the highenergy attrition milling of a mixture of metallic Y, metallic Cu and barium nitrate (Ba(NO&) containing 5 wt.% silver. +0.325Ag. Y 123-Ag superconductors in powder or bulk forms were prepared using heat treatment or thermomechanical processing of the intermediate precursor containing BaCuO,,. The high oxygen orthorhombic Y 123-Ag phase (y>7) was obtained in quenched samples which were held for 30 min or less at 950 "C in ambient air. As the holding time extended to 40 min, the sample was still orthorhombic Y123-Ag (6.79 7). The transport critical current density (Jc) at 77 K and zero magnetic field for the quenched sample which was held for 40 min at 950°C was -1.3~10~ A/cm*.

The influence of heat-treatment and oxygenation annealing on the superconducting properties of YBCO coated conductors

“…In ambient air (P O 2 160 Torr), a superconducting joint of YBCO CC is rarely obtained without melting the silver stabilizer layer that protects the superconducting layer because the melting temperature of YBCO is higher than that of silver, as shown in figure 1. However, a successful superconducting joint can be obtained without deformation of the YBCO CCs by reducing the P O 2 , which helps reduce the melting temperature of YBCO (see figure 1) [5][6][7][8][9][10][11][12][13][14]. On the other hand, heat-treatment under a reduced P O 2 , which is controlled directly by the out-diffusion of oxygen, can degrade the superconducting properties.…”