Transformation of Bi,Pb-2223 Phase From Multilayered Precursor Films
Bi,Pb-2223 phase on SrTiO3(100) fabricated by RF sputtering and annealing method have been investigated. We tried to fabricate Bi,Pb-2223 phase using multilayered precursors of Bi-2212 and Ca–Cu–Pb–O. We fabricated a multilayered film as a precursor by using two kinds of sputtering targets of Bi,Pb-2212 and Ca–Cu–Pb–O. After deposition by sputtering, the multi-layered precursor was annealed with Bi,Pb-2223 pellets at 840 °C for 100 h. From the X-ray diffraction (XRD) measurements, the main peaks of the precursor film were of Bi,Pb-2212 phase, but still remained large impurity phase. From the transmission electron microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) observation, we confirmed that a multilayer combination of a Bi,Pb-2212 layer and Ca–Cu–Pb–O layer was formed. After annealing, we determined the Tc through resistance measurements. The Tc value determined by the four-probe method was ${T_{\rm{c}}}^{{\rm{zero}}} = 104.5\,{\rm{K}}$. Furthermore, we observed two phases of Bi,Pb-2223 and Bi,Pb-2212 by XRD measurement. These results suggest that the Bi,Pb-2223 phase transformed from multilayered precursor film of Bi,Pb-2212 and Ca–Cu–Pb–O formed.