Thermodynamic Optimization of the Silver—Bismuth—Strontium—Calcium—Copper—Oxygen (Ag‐Bi‐Sr‐Ca‐Cu‐O) System

Abstract

Experimental data on the phase equilibria between the highcritical-temperature (high-T c ) superconducting compound 2212 and silver have been reviewed and assessed. Using these data, the interaction parameter of the Gibbs energy function of the liquid phase was optimized via the CALPHAD method. The calculation yields very good agreement with the experiment. This work is the final step in the optimization of the Ag-Bi-Sr-Ca-Cu-O system.

Understanding processing–microstructure–properties relationships in Bi2Sr2CaCu2Ox/Ag round wires and enhanced transport through saw-tooth processing

“…In the sample with T r2 = 873 • C, figure 16(c), filaments with Bi2201 grains are seen primarily as a result of a partial liquid-solid reaction. The secondary phase grains formed at this temperature consume the elements required for the formation of Bi2212 versus Bi2201 [45,56]. In the samples with T r2 = 874 and 877 • C (figures 16(d) and (e)), layered Bi2212 filaments are found primarily due to the higher content of Bi2212 phase formation and sufficient melt within the filaments.…”

“…Variations of T r2 significantly change the Bi2212 filament microstructure, which is understood through two different approaches. Firstly, the equilibrium phase diagram [45,56] of the Bi-Sr-Ca-Cu-O system is used to realize why T r2 is very effective in changing the transport properties and microstructure, as seen in figures 15 and 16. Based on the phase diagram [45], when calcium is between 0.8 and 1, there is a narrow window for the pure Bi2212 phase.…”