The Second Phase Particles Doped Single-domain Ybco Superconducting Bulk Properties Of The Ts-the Mtg

Since 1911, YBCO high-temperature superconductor discovered, not only critical temperature of high-temperature superconductor is up to 160K, but also the critical current of Y-based material by preparation of melting process is up to 105A/cm2(77K, 1T). Single domain YBCO bulk superconductors are highly appreciated because of their higher critical temperature, critical current density, levitation force and physical stability. This paper mainly studied properties of the nanoparticles Y2Ba4CuNbOx doped the single-domain YBCO bulk superconductors and the Nb2O5 dopant the single-domain YBCO bulk superconductors.YBCO bulk superconductors doped different Y2Ba4CuNbOx were prepared by top seeded melt texturing growth technique. Meanwhile, their macro-morphology, microstructure and levitation force were analyzed systematically. It is found optimum doping of Y2Ba4CuNbOx (3.5 wt%) in the series of samples.Secondly, we fabricated the single-domain YBCO bulk superconductors doped Nb2O5. Furthermore, their macro-morphology, microstructure and levitation force were analyzed. It is found optimum doping of Nb2O5 (2.0 wt%) in the series of samples.Before fabricated the nanoparticles Y2Ba4CuNbOx doped single-domain YBCO bulk superconductors, the initial powders of Y2Ba4CuNbOx, YBa2Cu3Ox, Y2BaCuO5 and Yb1.8Ba2.4Cu3.4Oy were synthesized firstly. The above mentioned initial powders were sintered by solid state reaction methods using four ball mill and three sintering steps. The powders were sintered at temperature of 1040℃,920℃,920℃and 910℃for 24h.During the preparation of the nanoparticles Y2Ba4CuNbOx doped single-domain YBCO bulk superconductors by the top seed melting texture growth method. Firstly, it is studied the phase structure and lattice parameters of the initial powders of Y2Ba4CuNbOx. Secondly, their macro-morphology, microstructure and levitation force of the nanoparticles Y2Ba4CuNbOx doped single-domain YBCO bulk superconductor were studied. The results of XRD showed that the crystal structure of Y2Ba4CuNbOx is cubic double pervoskite crystallographic structure with a unit cell size of 8.437A; It is found that the size of Y2Ba4CuNbOx is less than the size of Y2BaCuO5 in the nanoparticles Y2Ba4CuNbOx doped single-domain YBCO bulk superconductors and it belongs to nanomaterials. When the doping content of Y2Ba4CuNbOx (x=3.5wt%) the maximum number of Y2BaCuO5 particles, and particle size is also smaller.In the meantime, Furthermore, through observation and measurement of their levitation force of this series of single-domain YBCO sample with different Y2Ba4CuNbOx content. The levitation force was increasing gradually with the increasing of the Y2Ba4CuNbOx addition, the levitation force attained a largest value when x=3.5wt%. Further indicates that the best doped of Y2Ba4CuNbOx is 3.5wt%.It is studied macro-morphology,microstructure and levitation force of the single-domain YBCO bulk superconductors with different Nb2Ox dopant. The SEM analysis shows that small and uniform distribution of Y2BaCuO5 particles in the YBCO matrix, their average size is 0.81μm. When the doping content of Nb2Ox(x=2.0wt%) the maximum number of Y2BaCuO5 particles, and particle size is also smaller. Furthermore, through observation and measurement of their levitation force of this series of single-domain YBCO sample with different Nb2Ox content. The levitation force was increasing gradually with the increasing of the Nb2Ox addition, the levitation force attained a largest value when x=2.0wt%. Further indicates that the best doped of Nb2Ox is 2.0wt%.