Record flux pinning in melt-textured NEG-123 doped by Mo and Nb nano particles

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).

Field dependence of the super-current density in NEG-123 sample with 35 mol% content of Gd-211 (70 nm), and 0.1 mol% content of Nb2O3. Note the relatively high critical current density of 640 kA/cm2 at self-field and 77 K (H||c-axis) (left figure). Transmission electron micrograph of NEG-123 sample with 35 mol% Gd-211 (the initial average particle size 70 nm) and 0.1 mol% Nb2O5  the white arrows point to some of the nanometer sized  Nb-based nanoparticles (left figure)

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