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Effect of Sintering Temperature on the Microstructural and Flux Pinning Characteristics of Bi 1.6 Pb 0.5 Sr 1.8 La 0.2 Ca 1.1 Cu 2.1 O 8+δ Ceramics
Ist Teil von
Journal of the American Ceramic Society, 2009-02, Vol.92 (2), p.411-415
Erscheinungsjahr
2009
Link zum Volltext
Quelle
Wiley Blackwell Single Titles
Beschreibungen/Notizen
We evaluated the microstructure, superconducting, and flux pinning properties of La‐doped (Bi,Pb)‐2212 bulk sample by varying its sintering temperature (
T
sinter
) between 846° and 860°C. Significant variations in microstructure, self‐ and in‐field
J
C
s at 64 K and flux pinning properties have been observed for La‐substituted samples with respect to
T
sinter
. The sample sintered at 858°C shows best self‐field
J
C
while that sintered at 846°C shows the best in‐field
J
C
due to the changes in microstructure. The activation energy of flux motion (pinning potential
U
o
) is estimated from the field dependent resistivity–temperature curves, and the flux pinning force (
F
P
) from the field‐dependent
J
C
values. It is found that the La‐doped samples, sintered at 846°C show maximum
F
P
and
U
o
of 463 kN/m
3
and 0.380±0.001 eV as against 93.6 k/Nm
3
and 0.140±0.001 eV, respectively, for the sample sintered at 858°C. The undoped (Bi,Pb)‐2212 shows a maximum
F
P
and
U
o
of 12.7 k/Nm
3
and 0.074±0.001 eV, respectively. The origin of these enhanced properties is mainly from the normal‐like defects introduced by optimum La‐doping at the Sr‐site, at an optimum sintering temperature.