We refer on a highly improved pinning performance in the melt-textured (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy + 35 mol% Gd2BaCuO5 (70 nm in size) composite doped by tiny amounts of nanometer-sized MoO3 or NbO3 particles. The doping led to a spontaneous formation of clouds of extremely small ( 10 nm) (Nd,Eu,Gd)2BaCuXO5 particles, X = Mo, Nb. With an optimum content of MoO3 and NbO3 the self-field super-current at 77 K was two- and three-fold higher than before, respectively. At 65 K the super-current reached 700 kA/cm2 with Mo and 925 kA/cm2 with Nb, at both 0 and 4.5 Tesla, and the self-field current at 90 K was in the Nb-doped sample 100 A/cm2, the value high enough for a safe levitation. The present results make the new NEG-123 compounds highly promising for industrial super-magnet applications, especially in temperatures above boiling point of liquid nitrogen (77.3 K).
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