1 research outputs found
Recommended from our members
A study of parameters that influence growth and stability of the (Bi sub 1 minus x Pb sub x ) sub 2 Sr sub 2 Ca sub 2 Cu sub 3 O sub y phase
The growth and stability of the (Bi{sub 1-x}Pb{sub x}){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) phase contained in silver-sheathed wires has been investigated by a combination of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and transmission electron microscopy. Silver tubes loaded with Bi-2223 precursor powders were processed into filaments using established metallurgical techniques. The filaments were then heat-treated at selected temperatures (800 to 845{degrees}C) for a range of times (10 to 6000 min) in a 7.5% oxygen atmosphere. From these studies it has been possible to investigate the time-temperature-oxygen pressure domains wherein Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (Bi-2212) + second phases transform to Bi-2223. Fractional conversion (Bi-2212) {yields} (Bi-2223) versus time data show good conformance to the kinetic model for a diffusion-controlled reaction at the interface between thin sheets and a fine powder or a fluid. Quenching experiments also reveal that the Bi-2223 phase is stable in a limited temperature interval between 810 and 830{degrees}C