The ternary superconductors composed of three light rare earth elements in the elementary cell are a new class of high-Tc 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 Jc ever reported for bulk melt-processed samples. United States Patent: Patent Number 6 063 753, Date of Patent May 16, 2000, Muralidhar et al..
Scientists use unconventional spark plasma sintering method to prepare highly dense superconducting bulk magnesium diboride with a high current density. Spark plasma sintering (SPS) is