Contamination by alumina crucible and the effect of Al on T-c for Bi-2212 single crystals

The contamination by alumina crucible and the effect of Al impurity on crit ical temperature T-c of Bi-2212 single crystals were investigated systemati cally. The results indicate that the concentration of ill impurity in the c rystal due to the corrosion of alumina crucible is 0.046 per formula unit f or undoped Bi-2212 single crystal. The maximum value of Al concentration in the crystal is 0.115 per formula unit for Al-doped one. T-c of the Bi2.20S r1.95Ca0.80Cu2-xAlxOy single crystals decreases from 93 to 83 K with the in crease of Al content x ranging from 0 to 0.115. Besides, a reaction product of the melt with the alumina crucible was found, and its composition was e xamined to be (Sr0.62Ca0.38)AlO2.5 approximately. (C) 1999 Elsevier Science B.V. All rights reserved.