Title :
Synthesis of a high Tc superconducting phase in Bi-Sr-Ca-Cu-O system
Author :
Miyashita, S. ; Wakata, M. ; Nozaki, A. ; Egawa, K. ; Ogama, T. ; Yoshizaki, K.
Author_Institution :
Mitsubishi Electr. Corp., Kanagawa, Japan
fDate :
3/1/1989 12:00:00 AM
Abstract :
The synthesis of a high-Tc phase in the Bi-Sr-Ca-Cu-O system by the solid-state reaction and the Jc characteristics are reported. The partial pressure of oxygen near 0.1 atm is preferable as a sintering atmosphere, and Pb addition is effective to produce a large amount of high-Tc phase. Two classes of amorphouslike metastable superconducting phases with Tc of ~90 K and ~40 K, respectively, are found. It is thought that they have a randomly stacked structure. Jc of 93 A/cm2 at zero field, 77 K is obtained for the sample with Tc(ρ=0)=107 K, which includes a high-T c phase and a small amount of a low-Tc phase covered with the former phase. Jc is exponentially decreased by increasing the field. It is found that the transport Jc is limited by the weak-link regions in this system, as evidenced by the observation of a low resistive state above the Jc and of superconductivity in that state
Keywords :
bismuth compounds; calcium compounds; critical current density (superconductivity); high-temperature superconductors; sintering; strontium compounds; Bi-Sr-Ca-Cu-O; critical current density; high temperature superconductors; metastable superconducting phases; randomly stacked structure; sintering; solid-state reaction; weak-link regions; Atmosphere; Atmospheric measurements; Ball milling; Inductance; Metastasis; Performance evaluation; Phase detection; Powders; Pressure measurement; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
