Dependence of some Bi1.7Pb0.3Sr2Ca2Cu3Oy physical properties on the annealing period

By using solid state ceramic synthesis technique, we have produced high-Tc superconducting ceramics with a fixed nominal composition of Bi1.7Pb0.3Sr2Ca2Cu3Oy (BSCCO). Annealing treatments in air at 800 C for different time periods from 6 to 30 h were carried out for the BSCCO samples. The influence of annealing time on the superconducting and mechanical properties were examined by measurements of thermoelectric power (TEP), X-ray diffraction, surface morphology, bulk density and Vickers microhardness (V H N). The results reveal that the most appropriate annealing time to obtain the highest peak intensity of high-Tc phase (2223), highest and sharpest transition temperature (Tc0), maximum value of density and maximum of V H N is 18 h. Prolongation of the annealing time was associated with a reduction of all these parameters. These observations show that the annealing treatment plays an important role for producing consolidate superconducting compounds with improved mechanical properties. (orig.)