1 State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China;
2 National Engineering Laboratory for Superconducting Materials(NELSM), Western Superconducting Technologies(WST) Co. Ltd., Xi'an 710018, China;
3 Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China
The phase evolution of Bi-2223 precursor powder prepared by spray pyrolysis method is studied with different heat treatment parameters. The results show that the reaction temperature and phase composition of precursor powder depend on heat treatment atmosphere. Phase assemblage of (Bi,Pb)-2212, AEC, CuO, and small Bi-2201 can be obtained by heat-treated in N2-0.1%O2 atmosphere. For precursor powder, there is sufficient reaction process at 770℃, and the dimension of Bi-2212 phase increases rapidly with the increase of heat treatment temperature and time. The dimension of AEC phase also increases by extending heat treatment time. As a balance among phase assemblage, dimension of particle and adequate reaction, a reasonable precursor powder can be obtained by heat-treated at 770℃ for 12 h-16 h in N2-0.1%O2 atmosphere. Critical current of 37-filament Bi-2223 tape is about 120 A, which confirms that these heat treatment parameters are reasonable.
(Effects of material synthesis, crystal structure, and chemical composition)
Fund:
Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB0902303), the Key Research and Development Program of Shaanxi Province, China (Grant No. 2018GY-121N), and the National Key Project of Magneto Constrained Fusion Energy Development Program, China (Grant No. 2015GB115001).
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