Temperature Dependence of the Intergranular Critical Current Density in Uniaxially Pressed Bi1.65Pb0.35Sr2Ca2Cu3O10+δ Samples

• Published in: Journal of superconductivity and novel magnetism Vol. 23; no. 8; pp. 1511 - 1516
• Main Authors: García-Fornaris, I., Planas, A. A., Muné, P., Jardim, R. F., Govea-Alcaide, E.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.12.2010; Springer
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical currents; Exact sciences and technology; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Properties of type I and type II superconductors; Strongly Correlated Systems; Superconductivity; Weak links; Degree of texture; Electrical conductivity; Bi-based superconductors; Grain boundaries; Critical current density; Weak link; Bismuth Calcium Copper Lead Strontium Oxides Mixed; Superconductivity; Magnetic field effects; Texture; Heat treatments; Cuprates; Compacting; Solid state reaction; High-Tc superconductors; Transport processes
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-010-0805-x

We have studied the normal and superconducting transport properties of Bi 1.65 Pb 0.35 Sr 2 Ca 2 Cu 3 O 10+ δ (Bi-2223) ceramic samples. Four samples, from the same batch, were prepared by the solid-state reaction method and pressed uniaxially at different compacting pressures, ranging from 90 to 250 MPa before the last heat treatment. From the temperature dependence of the electrical resistivity, combined with current conduction models for cuprates, we were able to separate contributions arising from both the grain misalignment and microstructural defects. The behavior of the critical current density as a function of temperature at zero applied magnetic field, J c ( T ), was fitted to the relationship J c ( T ) ∝ (1− T / T c ) n , with n ≈ 2 in all samples. We have also investigated the behavior of the product J c ρ sr , where ρ sr is the specific resistance of the grain-boundary. The results were interpreted by considering the relation between these parameters and the grain-boundary angle, θ , with increasing the uniaxial compacting pressure. We have found that the above type of mechanical deformation improves the alignment of the grains. Consequently the samples exhibit an enhance in the intergranular properties, resulting in a decrease of the specific resistance of the grain-boundary and an increase in the critical current density.