Microstructure, critical current density and trapped field experiments in IG-processed Y-123

Abstract

In this paper, we adapted the top-seeded infiltration growth ‘IG’ technique and produced several YBa2Cu3Oy ‘Y-123’ samples with an addition of Y2BaCuO5 ‘Y-211’ secondary phase particles with varying sizes by the sintering process and the ball milling technique. For the first set of samples, Y-211 disks were sintered at temperatures ranging between 900 °C and 1100 °C and were used for the production of Y-123 material by the IG process. Magnetization measurements showed a sharp superconducting transition with an onset Tc at around 92 K, irrespective of the sintering temperature. However, the trapped field and critical current density (Jc) values were dependent on the sintering temperature and it was found that the best temperature is around 925 °C. Further, the trapped field distribution measurements at 77 K indicated that all samples are of single grain nature. The highest trapped field was recorded around 0.31 T at 77 K for the Y-123 sample with 20 mm in diameter and 5 mm thickness produced by Y-211 pre-from around 925 °C. On the other hand, a second set of samples Y-211 were controlled by ball milling technique combined with an optimized slow cooling process. As a result, the critical current density (Jc) at 77 K and zero field was determined to be 225 kA cm−2. The improved performance of the Y-123 material can be understood in terms of homogeneous distribution of fine secondary phase particles which is demonstrated by AFM micrographs.