We have detected a reproducible bulk superconducting transition in the Ba-Ca-Cu-O system at 126 K under ambient pressure. This is the highest transition temperature in a compound system not containing volatile toxic elements such as T1 or Hg. Two other distinct transitions at about 105 and 90 K were also detected. Careful investigation shows that the 126 K superconducting and other phases cannot belong to any of the known layered cuprate compounds. They may belong, instead, to a new compound family with a cation ratio of Ba: Ca: Cu= 2: n - 1: n. Steps are being taken to improve the granularity and stability of the phases for a definitive structure determination.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics