The Infiltration Growth Process of Single Grain YBa₂Cu₃O_y Bulk Superconductor: Optimization and Effect of Liquid Phase Mass and Its Day-to-Day Life Applications

Abstract

In top-seeded infiltration growth process (TSIG), an efficient production of single grain YBa₂Cu₃O_7-δ (Y-123) bulk demands single grains along with large size as it is crucial for applications of new class of super-magnets. In this process, the liquid plays a crucial role (e.g., such mixture of Y-123 and Ba₃Cu₅O₈). Recently, 1:1 mixture of Y-123 and Ba₃Cu₅O₈ is considered to be optimum for the production of single grain bulk Y-123 material. In this work, we utilized an innovative idea which is the implementation of low paratactic temperature YbBa₂Cu₃O_y (Yb-123) utilized to supply more liquid instead of Y-123. In search of an optimized liquid mixture and to attain long c-axis growth, we worked on the synthesis of bulk Y-123 material using a Yb-123 + Ba₃Cu₅O₈ rich liquid mixture and different liquid phase (LP) sources, i.e. Yb-123+liquid (1:1; 1:1.2; and 1:1.3), as a liquid source, isothermally grown at 995 °C for 50 h and studied its superconducting performance. Then, we had adopted a slow cooling process for the production of a TSIG processed YBa₂Cu₃O_7-δ bulk by utilizing Yb-123+ Ba₃Cu₅O₈ (1:1 and 1:1.3) as liquid phase. Bulk single grain Y-123 with 20 mm in diameter and 7 mm thickness was grown utilizing new liquid source even shorter time, i.e. 50 h. Four lines starting from top surface of seed until to sample edges and through c-axis direction can be observed, depicting the full-fledged bulk growth. Magnetic measurements revealed superconducting transition temperature (T_c) close to 90 K and a critical current density (J_c) of around 40 kA/cm² at 77 K in self-field without the influence of liquid phase mass. Trapped field distribution mimics a typical single cone with maximum value of 0.4 T at 77.3 K, 0.3 mm above top center of the Y-123 bulk. Note that this trapped field is more than three times the one measured for Yb-123+ Ba₃Cu₅O₈ (1:1) as liquid source using the same size and similar material. These results clearly indicate that processing of low peritectic temperature liquid (Yb123+ Ba₃Cu₅O₈) and its mass is crucial to obtain high quality TSIG processed Y-123 material that can be exploited for numerous industrial applications.