Two new superconducting Ba-Ca-Cu oxides were identified as Ba2Ca2Cu3(CaxCuy)O 8+δ and Ba2Ca3Cu4(CaxCuy)O 10+δ with Tc of 126 K and 116 K, respectively. The cations (CaxCuy), 0.4≤x≤0.9 and 0≤v≤0.7, are inserted between two adjacent BaO layers to stabilize the structures and to adjust the Cu-valences. Both compounds show the body-centered symmetry, but with different lattice constants of (a,c) = (3.8, 28.2) and (3.8, 34.8) Å , respectively. These compounds are unstable against the incorporation of CO2 and H2O in open air. The transformed products (Cau/2Cuv/2CxHy)2Ba 2Ca2Cu3O8+δ and (Cau/2Cuv/2CxHy)2Ba 2Ca3Cu4O10+δ have an expanded c of 33.8 and 40.2 Å , and a lower Tc of 90 and 114 K, respectively. The structure models for these decay products are proposed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering