High-Performance Ternary LRE-123 Superconductors

The ternary superconductors composed of three light rare earth elements in the elementary cell are a new class of high-T_c superconducting materials with promising super-current densities at high temperatures and high magnetic fields. These compounds were first prepared and intensively developed in SRL-ISTEC during last few years, since my employment in the lab. To increase current densities at low fields, a variety of normal secondary phase particles, like (Nd,Eu,Gd)₂BaCuO₅ (NEG-211), (Eu,Gd)₂BaCuO₅ (EG-211), and Gd₂BaCuO₅ (Gd-211) were introduced into the NEG-123 system. The emphasis led to the development of sub-micron 211 particles embedded in the superconducting matrix that could not be produced in other bulk superconductors (e.g. Y-123, Nd-123). As super-current density at low fields is inversely proportional to the average pinning defect size, the successful refinement of the secondary phase particles under the micrometer level resulted in a considerable increase of super-current density at 77 K. The samples exhibited the highest J_c ever reported for bulk melt-processed samples.  United States Patent: Patent Number 6 063 753, Date of Patent May 16, 2000, Muralidhar et al..