Flux pinning properties of (Nd,Eu,Gd)Ba₂Cu₃O_y(NEG-123) superconductor with 211 phase particles

Abstract

Flux pinning properties were investigated by focusing on the origin of the high peak critical current density and the high irreversibility field for Nd0.33Eu0.38Gd0.28Ba2Cu3Oy (NEG-123) bulk superconductors with the addition of 211 secondary phase particles of volume fractions up to 10 mol%. It was found that a negative correlation exists between the peak critical current density Jcp and the irreversibility field Bi for various fractions of added 211 phase. This suggests that the mechanisms that determine Jcp and Bi are different. The 211 particles do not contribute to the peak effect neither directly through the pinning mechanisms of the condensation energy interaction nor indirectly with the aid of the order–disorder transition of flux lines. Other possible defects are nano-lamella structures. Although these defects do not directly contribute to the peak effect through the pinning mechanism of the condensation energy interaction, they may contribute to it with the aid of the order–disorder transition of flux lines. On the other hand, as Bi deteriorates with the addition of 211 particles, it is not determined by the flux pinning of 211 particles. The decrease in Bi is considered to be caused by the proximity effect of nano-lamella structures.

Magneto-transport studies in (1-X) YBa2Cu3O7−+X BaTiO3 superconductors

“…The normal core vortices are pinned by these artificial defects at random points only when the pinning potential is sufficiently deep in comparison to the thermal fluctuations. Researchers have been constantly aiming on improving the pinning efficiency in YBa 2 Cu 3 O 7 (YBCO) system by chemical doping, introduction of secondary phases [15][16][17] and doping of impurities such as Gd and Ho [18,19]. In the thermally activated flux creep region the extrinsic point defects might be the main flux pining centers.…”

Improved flux‐pinning properties of REBa2Cu3O7–z films by low‐level Co doping

“…Many results have demonstrated that incorporation of periodic column defects comprised of self‐assembled BaZrO 3 nanorods and nanodots into the REBCO film can significantly enhance the flux‐pinning properties 2–4. In addition, flux‐pinning centers were also introduced by rare earth doping of yttrium 5, 6, addition of second‐phase particles 7, 8, and decoration of substrate surfaces by nanosize particles 9, 10. It is noted that the most outstanding results have been obtained in films and coated conductors prepared by the pulse laser deposition (PLD) approach 2, 7.…”

Strongly enhanced pinning force density in YBCO–BaTiO3 nanocomposite superconductor

“…There have been several reports on improving the pinning efficiency in YBCO system by chemical doping and introduction of secondary phases [5][6][7][8][9]. Doping of impurities such as Gd and Ho [5,6] have been reported to increase J c .…”

“…A much higher density of stacking faults was found in the doped samples which were believed to be acting as efficient pinning centres. The flux pinning by precipitates such as YBaCuO 5 [7,8] and Y 2 BaCuNbO x [9] have been found to increase the critical current density at lower field. The addition of nanoparticles of Al 2 O 3 [10], BaZrO 3 [11] and BaCeO 3 [12] have also been reported to improve the flux pinning properties in the YBCO system.…”