Effect of sintering periods on the pinning force, activation energy and microstructure of high- superconducting Bi - (Pb) - Sr - Ca - Cu - O tapes

Abstract

Short and long periods of sintering of short single-core (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x tapes have been studied. Comparisons are made between three batches of these tapes with the same thermomechanical deformation and sintering conditions but with the starting precursor powders having undergone different processing. It is found that the volume density of the macroscopic pinning force in fields up to 1 T is greater for a particular sintering period. Resistivity measurements further show that the pinning activation energy also reaches a higher value for the same chosen sintering period. SEM images of the surfaces indicate that better core morphology and density can be achieved with this particular sintering period. Prolonged sintering leads to greater porosity while short-duration sintering inhibits grain growth and thus is of no assistance in the healing of cracks induced during the intermediate deformation between sintering periods.

Characterization of high-temperature superconductors by AC susceptibility measurements

“…By enhancing the quality of the intergrain contacts, the difference between inter-and intragrain currents vanishes, and the two steps (and peaks) merge (Sauv et al 1993, Planinić et al 1994, Vo et al 1996. However, very small fractions (∼1%) of a poorer quality superconductor or the weak links in single crystals could be detected (Moreira et al 1994, Ren et al 1994 by AC susceptibility.…”

A multi-step process to improve texturing and transport current in BSCCO (2223) superconductors

“…From this it can be inferred that by enhancing the quality of intergrain contacts through densification and texturing the difference between inter-and intra-grain current vanishes and the two respective peaks (and steps in the real component curve), at least at the lowest fields, merge [12]. 3) Starting composition 2': Using powder with stoichiometry Z and prepared by pyrolysis, sample E was prepared through HF procedure completed of high temperature peak at 885 "C: after processing only 2223 phase was detected by XRD.…”

Some effects of the doping with alpha - Al_2O_3 nanoparticles in the transport properties of Bi_1.65 Pb_0.35 Sr_2Ca_2 Cu_3O_y ceramic superconductors

“…The little differences between the Ghattas and our results, could be due to the method used in both works. For example, the influence of compacting pressure modified the transport properties [4,5]; the sintering time variation [6] can modified these properties too. Beyond of the different method used in these papers, the main results are very similar.…”

“…Moreover, the pinning potential is one of the basic parameters that defines the performance of a superconducting material for commercial and technological applications [3]. In general, the granular superconducting materials can be modified into a material with better transport properties, for example: varying the compacting pressure [4,5], varying the sintering time [6], by chemical doping and nanosized particles addition [7][8][9][10]. For example, Ghattas et al [3] analyzed the effects of α-Al 2 O 3 NPs addition on the microstructure and pinning properties of polycrystalline (Bi,Pb)-2223 samples.…”