The difference between the onset critical temperatures determined by the measurements of a dc-electrical resistivity (Tcor) and of an ac-susceptibility (Tcox) was examined. In the early stage of the calcination, the resistivity can be zero even when the fraction of the superconductive volume (V) is about 3-6%, but the difference between Tcor and Tcox is large. When V is larger than 60%, Tcor and Tcox coincide well with each other. The V dependence of Jc is drastically large around V = 100%, therefore, a very high completeness of the superconductive compound is indespensible to a high Jc.
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