TY - JOUR
T1 - Optimization of superconducting transition temperature in (Pb0.7Cu0.3)Sr2(Ca0.5Y0.5)Cu2O7+δ by postannealing
AU - Hu, S. F.
AU - Jefferson, D. A.
AU - Liu, R. S.
AU - Edwards, P. P.
N1 - Funding Information:
We thank the Fellowship of Engineering, SERC, and BP for support.
PY - 1992/2
Y1 - 1992/2
N2 - We demonstrate systematic studies of the optimization of the superconducting transition temperature in (Pb0.7Cu0.3)Sr2(Ca0.5Y0.5)Cu2O7+δ by annealing in an oxygen atmosphere. As-sintered samples with a superconducting midpoint transition temperature, Tc(midpoint), of 18 K were prepared by solid state reaction at 1000°C for 1 hr in oxygen and then quenched in air. Subsequently, the samples were annealed in the temperature range between 700 and 1000°C for 12 hr in oxygen and then rapidly quenched in air. The ultimate Tc(midpoint) increased from 30 to 48 K with an increase in the annealing temperatures from 700 to 800°C, but a further increase in the annealing temperature of the samples from 800 to 1000°C resulted in a decrease in Tc(midpoint). Based on our studies, we believe that the optimum Tc(midpoint) of 48 K arises from the removal of excess oxygen in the insulating slabs of (Pb,Cu)O in (Pb0.7Cu0.3)Sr2 (Ca0.5Y0.5)Cu2O7+δ and this leads the material to approach an optimum hole concentration.
AB - We demonstrate systematic studies of the optimization of the superconducting transition temperature in (Pb0.7Cu0.3)Sr2(Ca0.5Y0.5)Cu2O7+δ by annealing in an oxygen atmosphere. As-sintered samples with a superconducting midpoint transition temperature, Tc(midpoint), of 18 K were prepared by solid state reaction at 1000°C for 1 hr in oxygen and then quenched in air. Subsequently, the samples were annealed in the temperature range between 700 and 1000°C for 12 hr in oxygen and then rapidly quenched in air. The ultimate Tc(midpoint) increased from 30 to 48 K with an increase in the annealing temperatures from 700 to 800°C, but a further increase in the annealing temperature of the samples from 800 to 1000°C resulted in a decrease in Tc(midpoint). Based on our studies, we believe that the optimum Tc(midpoint) of 48 K arises from the removal of excess oxygen in the insulating slabs of (Pb,Cu)O in (Pb0.7Cu0.3)Sr2 (Ca0.5Y0.5)Cu2O7+δ and this leads the material to approach an optimum hole concentration.
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U2 - 10.1016/S0022-4596(05)80282-8
DO - 10.1016/S0022-4596(05)80282-8
M3 - Article
AN - SCOPUS:0347807979
VL - 96
SP - 455
EP - 460
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
SN - 0022-4596
IS - 2
ER -