Inhomogeneous distribution of the intergranular pinning energy in polycrystalline Bi1.64Pb0.36Sr2Ca2Cu3Oy superconductors

Superconducting and transport properties of (Bi–Pb)–Sr–Ca–Cu–O with Cr2O3 additions

“…The anomalous T C-zero for the x = 0.5 wt.% sample may be due to homogeneity in the sample and effective pinning centers due to Cr substitution for Cu, while excessive Cr-ion doping degraded the superconductivity of Bi2223, which can affect the transport properties in this type of materials [15,16].The lower zero resistance transition temperature with increasing Cr 2 O 3 content could be interpreted as a result of the suppression of superconductivity by the Cr 3+ ions. It was observed that Cr 2 O 3 doped samples showed a broader transition, which indicates presence of impurities and weak links between superconducting grains.…”

Consolidation of Bi-2223 superconducting powders by spark plasma sintering

“…We mention that the density of this sample is rather 23 This is expected to occur along the axis of the sample (face-L), a feature much less pronounced at the interface (face-S), where the piston used for the compacting process has a direct mechanical contact with the powders. 17 We also mention that, due to the prolonged sintering time (see Table III), the grains of the reference sample 84PA are homogeneous and not oxygendeficient, being responsible for high values of T on . In accordance with the T-linear behavior of the q(T) curves for T > 100 K and the relatively sharp superconducting transition width, the material has a low concentration of defects, dislocations, or other nonuniform microstrutural features and a very clean grain boundaries.…”

“…Such a behavior contrasts with previous results obtained in Bi-2223 pellets subjected to higher, up to $300 MPa, uniaxial pressures. 17 In those samples, an inhomogeneous distribution of the microstructural parameters such as the degree of texture and the grain connectivity were found when the structural properties along both faces (S and L) are compared.…”

Pinning mechanism in (Bi,Pb)-2223 polycrystalline samples prepared with Al2O3nano-particles

“…Fig 1a and b, where ) K 120 ( ñ is the resistivity at temperature 120 K. A broadening of the resistive transition with an increase of the applied magnetic field is obviously observed. Such behavior is a remarkable feature of granular superconductors [7,8]. In the presence of the magnetic field, the ) H , T ( ñ curves are characterized by two distinctive sections; at high temperature a branch which reveals the intragranular transition and at lower temperature a broad foot structure associated with the grain-boundaries network or intergranular effects, which are considered to be weak Josephson type links [9].…”