Electric resistivity and magnetic susceptibility studies of Tl-1223 substituted by cobalt

Abstract

Bulk superconductor samples of type TlBa 2 Ca 2 (Cu 3−x Co x )O 9−δ with 0 x 0.6 were prepared by a single-step solid-state reaction. The prepared samples were characterized by powder x-ray diffraction and the superconductivity of these samples was investigated by electrical resistivity and ac magnetic susceptibility. The x-ray data indicate that the lattice parameters a and c vary but the structure of Tl-1223 remains tetragonal with cobalt substitution up to x = 0.6. The transition temperature 'T C ', deduced from electrical resistivity and ac magnetic susceptibility measurements, is suppressed by substituting Co impurities at Cu sites. The suppression in T C has been discussed using a Cooper pair-breaking mechanism due to the Abrikosov and Grokov model. The effects of external magnetic field on the ac magnetic susceptibility as well as calculations of critical current density as a function of cobalt content and temperature are reported.

Superconducting properties of zinc substitution in Tl-2223 phase

“…It is generally accepted that the values of q are related to the dimensionality of Abrikosov vortices. In particular, q ≈ 2 implies they behave as three dimensional (3D) flux lines [29,30] as reported by Batista-Leyva et al [31] for Tl-1223 system, by Tang et al [32] for Tl-1223/Ag, Triscone et al [33] for (Tl, Pb, Bi)(Sr, Ba) 2 Ca 2 Cu 3 O 9−δ superconductors and by Isber et al [23] for TlBa 2 Ca 2 (Cu 3−x Co x )O 9−δ system. Glowacki [34] obtained similar results for different composites.…”

“…Therefore, filamentary paths can produce sharp pronounced drops in diamagnetism, which also require extensive regions of superconductivity. Such filamentary behavior can be described in terms of percolation thresholds [23].…”

A Search for a Low Anisotropic Superconductor

“…The increase in T c (0) was attributed to the improved coupling between the CuO 2 planes due to the decreased c-axis length [100]. The critical temperature and the critical current density of Tl-1223 superconductor decreases with low level doping concentration of 3d transition metals Co, Zn, Fe and Ni at Cu site and superconductivity disappears for higher concentrations of these elements [101][102][103][104]. The presence of these ions in CuO 2 planes acts as scattering centers, which resulted in the Cooper pair breaking, and destroys the superconducting state in Tl-1223 compounds.…”

Effect of Sm-substitution on the electrical and magnetic properties of (Tl0.8Hg0.2)-1223

“…The contraction rate of c with increasing Sm-content is estimated to be (dc/dx) = −0.277. This means that the elongation rate in the lattice parameter "a" is less than the contraction rate in the lattice parameter "c", indicating a strong Cu-O bond length within the planes (xy-planes) than that along the normal to xy-planes [20].…”