The present invention relates to a method of manufacturing oxide superconductor elements, and more particularly to a method of manufacturing Bi-based superconducting ceramic materials.
Recently, superconducting ceramics comprising Bi have been discovered as promising materials which can be formed to have high Tc. The Bi-based superconducting material takes two phases, in one of which, called the low Tc phase, the critical temperature reaches up to 80.degree. K., and in the other, called the high Tc phase, the critical temperature reaches up to 110.degree. K. An example of the stoichiometric formula of the low Tc ceramic is Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8-x having its c-axis length of 30 .ANG.. An example of the stoichiometric formula of the high Tc ceramic is Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10-x having its c-axis length of 36 .ANG.. In this low Tc phase, there are formed three CuO planes within one unit structure thereof. In accordance with recent reports, there are other phases having their c-axes of 42 .ANG. and 48 .ANG. which phases there are formed CuO-(Sr, Ca) planes in addition to the three CuO plane. It is believed for this reason that the resistivity of Bi-based superconductors begins to fall down at 150.degree. K. or higher temperatures.
In spite of past efforts, it has been still difficult to increase the proportion of the high TC phase in the formation of Bi-based superconducting ceramics. Also, single crystals of the high Tc phase have not be formed yet.