MECHANOCHEMICAL EFFECTS OF GRINDING ON THE BI-PB-SR-CA-CU-O SUPERCONDUCTOR

The effects of mechanical grinding on the powder of the Bi-Pb-Sr-Ca-Cu-O superconductor (so-called “high Tcphase”) were examined. The grain size of the powders decreased with increased grinding time accompanied by the degradation of crystallinity. Powders involving relatively lower crystal strain recovered their crystallinity as “high Tcphase” by postheat treatment. But powders having relatively excessive crystal strain recrystallized as “low Tcphase” and others. Such an effect reveals the metastability of the high Tcphase under the condition of excessive crystal strain. © 1990 IOP Publishing Ltd.