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ORAL CONTRIBUTIONS
Electric field-assisted consolidation of (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+y ceramic
samples
E. Govea-Alcaide 1 , I. F. Machado 2 , P. Muné 3 , and R. F. Jardim 4
1
Departamento de Ciencias Básicas, Facultad de Ciencias, Técnicas, Universidad de Granma,
Apdo. 21, P. O. Box. 85100, Bayamo, Cuba, e-mail: egoveaa@udg.co.cu
2 Departamento de Engenharia Mecatrônica e Sistemas Mecânicos, Escola Politêcnica,
Universidade de São
Paulo, 05508-900, São Paulo, SP, Brazil, e-mail: machadoi@usp.br
3 Departamento de Física, Universidad de Oriente, Patricio Lumumba s/n, P.O. Box 90500,
Santiago de Cuba, Cuba, e-mail: mune@cnt.uo.edu.cu
4 Instituto de Física,Universidade de São Paulo, CP 66318, 05315-970, São Paulo, Brazil, e-
mail: rjardim@if.usp.br
Pre-reacted powders of Bi 1.65 Pb 0.35 Sr 2 Ca 2 Cu 3 O 10+y (Bi-2223) were consolidated by
using the spark plasma sintering (SPS) technique. The influence of the consolidation
temperature, TD, on the structural and electrical properties has been investigated and
compared with those of a reference sample synthesized by the traditional solid-state
reaction method and subjected to the same compacting pressure. The uniaxial
compacting pressure used in all samples was 50 MPa. From the X-ray diffraction
patterns, performed in both powder and pellet samples, we have found that the dominant
phase is the Bi-2223 in all samples, but traces of the Bi 2 Sr 2 CaCu 2 O 8+y (Bi-2212) were
identified. Their relative density were ~ 85 % of the theoretical density. The
temperature dependence of the electrical resistivity, ρ(T), indicated that increasing TD
results in samples with low oxygen content because the SPS is performed in vacuum.
Features of the the ρ(T) data, as the occurrence of normal-state semiconductor-like
behavior of ρ(T) and the double resistive superconducting transition, are consistent with
samples comprised of grains with shell-core morphology in which the shell is oxygen
deficient. In addition, the SPS samples also exhibited superconducting critical current
density at 77 K, Jc(77K), between 2 - 10 A/cm2, values much smaller than ~ 22 A/cm2
measured in the reference sample. Re-oxygenation of the SPS samples, post-annealed in
air at different temperatures and times, was found to improve their microstructural and
transport properties. Besides the suppression of the Bragg peaks belonging to the Bi-
2212 phase, the superconducting properties of the post-annealed samples and
particularly Jc(77K) were comparable or better than those corresponding to the
reference sample. Post-annealed samples at 750 oC for 5 min exhibited Jc(77K) ~ 130
A/cm2 even when uniaxially pressed at only 50 MPa.
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