Phase stability and microstructural evolution of bismuth strontium calcium copper oxide superconducting ceramic oxides
Abstract
The use of high-T$\rm\sb{c}$ superconductors in commercial applications requires that the superconducting properties be maximized. More importantly, easy and rapid synthesis of single phase materials is required. Although many different processing routes have been attempted, the true stabilities of the superconducting oxides have not been accurately examined. The current investigation of the phase stability limits of $\rm Bi\sb2Sr\sb2Ca\sb1Cu\sb2O\sb{8+x}$ involves examination of Bi-2212 powder processing, thermal analysis and materials characterization. The phase stability limits were investigated when the material was at thermal equilibrium. The oxygen non-stoichiometry was measured by thermal gravimetric analysis from 300$\sp\circ$C to 1000$\sp\circ$C in $3\times10\sp{-3}$ atm to 1.0 atm oxygen. Phase stability and decomposition reactions are documented. Additional microstructural evolution of phases is compared during thermal analysis of equilibrated specimens. The phase stability diagram for Bi-2212 as a function of oxygen partial pressure and temperature is determined. This diagram can be utilized to optimize the processing of this superconducting material. This research was supported by U.S. Department of Energy, Office of Basic Energy Sciences, and in part by the Midwest Superconductivity Consortium under DOE Grant No. DE-FG02-90ER45427.
Degree
Ph.D.
Advisors
Gaskell, Purdue University.
Subject Area
Materials science|Condensation
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