Phase Relations of the Bi-2201-CuO Pseudobinary Join as a Function of Oxygen Pressure
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Phase Relations of the Bi-2201–CuO Pseudobinary Join as a Function of Oxygen Pressure James K. Meen, Karoline Müller, Celia Salmeron, and Don Elthon Department of Chemistry and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, U.S.A. ABSTRACT Phase relations on the join Bi-2201–CuO have been determined as a function of P(O2). Most of the major changes that occur between P(O2) of 1 and 0.01 atm occur in the most oxidizing part of the range. Stoichiometric Bi-2201 occurs only at the most oxidizing conditions and in a narrow temperature range near the solidus. In the Bi-2201–CuO system, the ternary phase that forms has higher Bi:Sr and Cu:Sr than Bi-2201. That phase, Sr14Cu24Oy, and CuO occur in the subsolidus and the invariant point at which they coexist with liquid is a ternary eutectic. The liquid is more Sr-rich than the Bi-2201–CuO join. Decrease in P(O2) produces a change in the Bi2201 solid solution so that stoichiometric Bi-2201 does not occur. At P(O2) ≤0.5 atm, all Bi2201 solid solutions have Bi:Cu
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