Bi-2212 current leads prepared by the diffusion process

Abstract

Bi-2212 oxide superconducting current leads have been prepared by the diffusion process. The Bi-2212 diffusion layer is synthesized through diffusion reaction between a Sr-Ca-Cu oxide substrate and a Bi-Cu oxide coating layer with Ag addition. The Bi-2212 diffusion layer, about 150 /spl mu/m in thickness, formed around the cylindrical tube and rod shows dense and textured structure with plate-like grains. The transport Jc of the diffusion layer exceeds 20000 A/cm/sup 2/ at 4.2 K under self-field. The transport Ic of the rod specimen 3 mm in diameter exceeds 300 A at 4.2 K. The transport Ic of the tube specimen 20/16 mm in outside/inside diameter exceeds 2500 A, and is estimated to be 4000 A at 4.2K under self-field. The Joule heating of the electrodes formed on both ends of the tube specimen is 5-7 mW since the overall voltage of the electrodes is 5-7 /spl mu/V at 4.2 K and transport current of 1000 A. Therefore, the total heat load, including heat leakage conducted through bulk tube specimen between 4 K and 40 K, is expected to be less than 100 mW at a current of 1000 A. Present Bi-2212 oxide conductors with large transport Ic as well as low resistance and thermal conductivity, seem to be promising as current leads for superconducting magnets.