In situobservation of 2212 intergrowths in the early stages of (Bi, Pb)2223 phase formation using the synchrotron XRD technique

Abstract

2212 intergrowths in the (Bi, Pb)2223 phase have been investigated using in situ high temperature synchrotron XRD technique. With a high energy synchrotron x-ray and high resolution diffractometer, we could obtain high resolution powder XRD patterns of (Bi, Pb)2223 and (Bi, Pb)2212 from the whole bulk inside the Ag-sheath. This gave us more detailed information on 2212 intergrowths in the (Bi, Pb)2223 phase than ever before. During in situ observation, the Ag-tubed precursor was kept at 1095 K with flowing Ar-7.8% O 2 mixed gas. The profiles of the diffraction peaks were analysed by Rietveld analysis to evaluate the isotropic and anisotropic lattice strain of (Bi, Pb)2223 and (Bi, Pb)2212. Considering the evolution of anisotropic lattice strain during the heat treatment, it was concluded that 2212 intergrowths in the (Bi, Pb)2223 phase are not in the untransformed region of (Bi, Pb)2212 after incommensurate intercalation, but a stacking fault-like defect contained in the (Bi, Pb)2223 phase during its nucleation and growth. A new model of 2212 intergrowth formation in the (Bi, Pb)2223 phase was suggested and discussed.

Phase evolution and the mechanism ofJcincrease during post-annealing in Ag/(Bi, Pb)2223 tapes

“…During the (Bi, Pb)2223 phase transformation, Bi 2 Sr 2 Ca Cu 2 O 8 (Bi2212) melts partially, with secondary phases present, and a liquid phase appears at the early stage of the sintering process [6,7]. After the partial melting, the reaction of (Bi, Pb)2212 with the liquid phase leads to (Bi, Pb)2223 formation.…”

“…Powder XRD Rietveld analysis is very powerful and useful for investigating the phase evolution inside the Ag sheath during the heat treatment process [7,8]. We have succeeded in determining quantitatively the content of phases in the superconducting filament through Rietveld analysis of powder XRD data in spite of the ex situ observation using the conventional powder XRD technique [8].…”