Effects of the Sintering Conditions on the Structural Phase Evolution and T C of Bi1.6Pb0.4Sr2Ca2Cu3O7 Prepared Using the Citrate Sol–Gel Method

The effects of the sintering temperature and time on the phase evolution, microstructure and superconducting properties in a typical Pb-doped Bi-Sr-Ca-Cu-O (BSCCO) system, Bi1.6Pb0.4Sr2Ca2Cu3O7, were examined systematically by X-ray diffraction (XRD), thermo gravimetric-differential thermal analysis, scanning electron microscopy, and four-point probe resistivity measurements. The samples were prepared by the citrate based sol–gel method using their corresponding nitrates as the starting materials. The samples were sintered at different temperatures, ranging from 820 to 860 °C with different dwell-times (24–120 h). The results showed that the sintering temperature had a significant effect on the structure and superconducting transition temperature (TC). XRD showed that when the samples were heat treated at 550 °C, the BSCCO 2201 phase appeared, whereas peaks corresponding to the BSCCO 2112 phase were dominant at 800 °C. At 840 °C, only the peaks corresponding to the BSCCO 2212 and 2223 phases were detected with no impurities. A strong correlation was observed between the structural data andTC; the samples sintered at 840 °C for 120 h exhibited the maximum \(T_{\mathrm {C}}^{\text {onset}}\)(115.7 K). Journal of Superconductivity and Novel Magnetism; June 2016, Volume 29, Issue 6, pp 1491–1497