The stability of the Bi2minus;xPbxSr2Ca2Cu3O10(Pbhyphen;2223) phase contained in silverhyphen;sheathed oxidehyphen;powderhyphen;inhyphen;tube specimens has been investigated by xhyphen;ray diffraction, transmission electron microscopy, and energy dispersive xhyphen;ray analysis. Silver tubes loaded with Pbhyphen;2223 precursor powders were processed into tapes using established metallurgical techniques. The tapes were heathyphen;treated in a specially designed equilibration apparatus at selected temperatures (800ndash;845thinsp;deg;C) for a range of times (10ndash;5500 min) and quenched in liquid gallium held at sim;40thinsp;deg;C. The results showed that the Pbhyphen;2223 phase is stable in a limited temperature interval between 810 and 830thinsp;deg;C in 7.5percnt; oxygen. At 800thinsp;deg;C, this phase decomposes to Bi2Sr2CaCu2O8(2212), Ca2PbO4, and CuO; while at temperatures ge;840thinsp;deg;C it partially melts with precipitation of Bi2Sr2CuO6(2201) and Ca2CuO3. The effects of the silver cladding on the Pbhyphen;2223 phase stability and microstructure are also discussed.
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