Preparation of Fibers of Bi-Based Superconducting Ceramics

1.细棒、细卷：(1)将熔体真空浇注到一定形状的石英玻璃管中，成功地制备出了具有一定形状的前驱体陶瓷，如细棒(直径为mm mm)和细卷，并通过800℃左右的二次加热将玻璃前驱体转变为超导多晶陶瓷，确定了加热温度和保温时间的最佳加热条件，并从加热过程中的吸氧性能进行了讨论。用这种工艺可以很容易地制备出长达50 cm的超导细棒(Tc85K)。(2)到目前为止，前驱体铸态陶瓷一直在含氧气氛中加热，以便转变为超导陶瓷。在本研究中，我们发现掺银熔体的铸棒在真空密闭容器中，即在无氧气氛中加热时，会转变为超导体。这一发现表明，x，7e能够制备出封闭在玻璃中的所需形状的超导铋基陶瓷。晶须：以Al_2O_3为添加剂，确定并讨论了超导晶须(2212相)的最佳制备条件。

1. Fine rods, Coils :(1)A given shape of precursor ceramics such as fine rods mm diameter)and coils in the system of Bi-Sr-Ca-Cu-0 was successfully fabricated by a vacuum casting of the melts into a given shape of silica glass tube ; the glassy precursors, as-cast specimens, were converted into superconducting polycrystalline ceramics by reheating them at around 800'C. The optimum heating conditions for heating temperature and-duration time were determined, and discussed in terms of oxygen absorption during heating of the specimen. Superconducting fine rods(Tc 85K)up to 50 cm length were easily prepared by this process.(2)Up to date, the precursor as-cast ceramics have been heated in oxygen-containing atmosphere in order for the conversion into superconducting ceramics. In this study, we found that the as-cast rods of Ag2O-doped melts are converted into superconductor when heated in a vacuum sealed-vessel, i. e., in oxygen-free atmosphere. This finding indicates x, 7e are able to fabricate a desired shape of superconducting Bi-based ceramics sealed in glasses.2. Whiskers : Optimum preparation conditions of superconducting whiskers (2212 phase) were determined and discussed in terms of Al_2O_3 additives.