Phase Composition and Compatibilities in the Bi‐Sr‐Ca‐Cu Quaternary Oxide System at 800°C in Air

Abstract

Subsolidus phase relations in the system (Bi-Sr-Ca-Cu)-0 at 800°C were investigated via powder X-ray diffraction and electron probe microanalysis of solid-state reaction products. Two recently reported (Bi-Sr-Ca)-0 phases were detected in quaternary assemblages and had the approximate cation stoichiometries of 9115 and 825. The only truly quaternary compound detected is the superconducting phase with the cation stoichiometry 2212. Tie lines, tie triangles, and compatibility tetrahedra involving this phase and the 2201 superconducting phase were determined. Both superconducting compounds exhibit small but detectable Sr-to-Ca solubility and are Sr-deficient with respect to the "ideal'' formulas. [

Preparation and Structural Investigation of Bi16(Sr,Ca)14O38

“…Single-crystal X-ray diffraction was used to investigate the phase was referred to as the "2110" phase by Muller et al 6 and structure of the ternary oxide of approximate formula Suzuki et al 7 and as the "8250" phase by Hong et al 8 Roth Bi 14 (Sr,Ca) 12 (BSCCO), this phase was found to be in equilibrium with the substitute for each other. The structure consists of a nettwo-layer 80 K high T c "2212" phase and also with the onework of alkaline-earth oxide polyhedra with broad channels layer "11905" phase.…”

Growth of Bi2Sr2Ca1−xPrxCu2Oy single crystals by traveling solvent floating zone method

“…17 Table 1. This compositional range, which has been normally considered with a higher melting point, was determined to have mixed phases consisting of Bi-2212, Bi-2201 and CuO [22,23]. A striking feature here is that in the Pr2212 systems, we propose CuO-rich PCFs as eutectics with lower melting points.…”

Phase relations and alignment in bismuth-based high-Tc wires

“…The technique has the advantage that the phases are studied in situ; but because of the shallow penetration depth of x-rays (about 3-5 Jlm for CU-K a 27), only films can be studied. When the HTXRD system is supplied with a high-intensity source and a position-sensitive detector, the phase progression during heating or cooling can be followed in very close to real time, as has been done by Polanka et al2 8 With high-temperature optical microscopy,29,JO the phases are observed insitu and are subsequently identified in cooled samples. Phase formation as a function of time can be studied using a video recorder.…”

“…Consequently, the crystalline phases in the melt are not consumed on forming 2212, but instead are present in the fully processed tape. I , 21,22 These are metastable phases that do not coexist with 2212 in the solid state, 8,17 The metastable phases shift the liquid composition away from2:2:1 :2, and since they are not consumed on cooling, the liquid cannot transform completely to 2212 on cooling. The phases that persist from the melt are too large to pin flux effectively, and they degrade J e • In the most deleterious phase, (Sr,Ca)Cu0 2 , large grains are formed that approach the thickness of the oxide core.…”