Optimization of intergrain connection in high-temperature superconductor Bi2Sr2CaCu2Ox**Project supported by the National Basic Research Program of China (Grant No. 2011CBA00104), the National Natural Science Foundation of China (Grant No. 51472206), the ITER Project of China (Grant No. 2013GB110001), and the Program for Innovative Research Team in Shaanxi Province, China (Grant No. 2013KCT-07).

Abstract

A modified spark plasma sintering (SPS) technique was developed for the fabrication of Bi2Sr2CaCu2Ox (Bi-2212) superconducting bulks with better intergrain connections. The influences of the modified SPS process on the microstructures, intergrain connections, and related superconducting properties were systematically analyzed. The modified SPS process can not only increase the final density of the bulk samples but also enhance the texture structures. Clean grain boundaries were obtained instead of the intergrain amorphous layers. Therefore the intergranular properties were obviously improved. Due to the better intergrain connections and the stronger flux pinning properties, the critical current densities of the Bi-2212 bulks obtained via the modified SPS process were greatly increased. The obtained improvements imply the possibility for the modified SPS technique to be used for enhancing the superconducting properties of the Bi-2212 tapes.