Microstructure and Critical Current Density of YBa 2 Cu 3 O 7-x -Ag Composites Compressed at High Temperature

• Published in: Japanese Journal of Applied Physics 1992-10, Vol.31 (10R), p.3311
• Main Authors: Kang, Whang-Jin, Hanada, Shuji, Yoshii, Isamu, Nagata, Akihiko
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.31.3311

Microstructures of YBa 2 Cu 3 O 7- x -Ag composites compressed at high temperatures have been investigated, and relationship between the microstructures and superconducting properties is discussed. YBa 2 Cu 3 O 7- x specimens doped with 20 and 30 w/o Ag 2 O were well compressed to 55% plastic strain under a low stress level compared to the Ag 2 O-undoped sample. No microcracks were observed in the central zone of the composites reoxidized at 773 K for 18 h after compression at 1203 K and at 1.3×10 -5 /s. From this result, it is suggested that uniformly distributed Ag particles play an important role not only in ductile deformation at high temperatures but also in relieving the anisotropic stresses induced by phase transition and reoxidizing heat treatment. The maximum J c(trans) value of 1400 A/cm 2 at 77 K and 0 T was obtained in 20 w/o Ag 2 O-doped composites. The agglomerations of Ag particles, which were formed during compression of the 30 w/o Ag 2 O-doped sample, reduced the path of the current flows and eventually decreased J c(trans) .