Effect of Sintering and Annealing Temperatures on the Critical Temperature and Electrical Resistivity of Bi2Ba2Ca2Cu3O10+δ

Samples of the high temperature superconducting system, Bi2Ba2Ca2Cu3O10+δ, were prepared by using the solid state reaction method with different sintering temperatures of 810, 830, 850, 870 and 890 °C. The electrical resistivity measurements exhibited that the sintering and annealing conditions have major effects on the critical temperature of the superconducting compound. The sample prepared at 850 °C has a critical temperature Tc ≈ 110 K, meanwhile the sample prepared at 870 oC has a critical temperature ≈ 80 K. However, the sample which was prepared at 890 °C showed semiconducting behavior with an activation energy of 6.40 meV. The effect of annealing on the critical temperature has been investigated using the sample prepared at 850 °C. The value of Tc at the annealing temperature of 400 °C rises from 110 K to 138 K with increasing the annealing time from 24 hrs to 72 hrs. This increase might be due to the increase of oxygen content or to the intergrowth of a large number of Cu-O layers in the cell.