Melt texturing of YBCO for high current applications

Abstract

Abstract In recent years significant progress has been made in J c enhancement in high T c superconductors using melt texturing techniques. Among the many melt texturing methods and modifications, seeding and directional solidification techniques offer extensive control over the location of the growth front and the growth direction over long distances during melt texturing which makes these techniques most attractive from the standpoint of long conductor fabrication. These processes have the capability of producing J c s of about 45 000 A cm −2 across single domains of YBCO. A novel variant of the conventional melt texturing process called the liquid phase removal method provides a means to improve the grain boundary coupling in melt textured bulk polycrystalline HTS. Grain boundaries in samples processed by this technique with misorientation angles as high as 54° have demonstrated J c s as high as 18 000 A cm −2 . Recent developments in texturing of RE-123 compounds (Nd and Yb) at high growth rates give promise for considerable reduction in processing times in directional solidification. Texturing has been observed even in samples processed at rates as high as 100 mm h −1 . With these advances in melt texturing methods, utilization of bulk HTS in practical applications such as high capacity current leads etc., appears to be a distinct possibility of the near future.