Observation and identification of a 107 K superconducting family in the CaBa2Ca2Cu3O9-δ system
Journal
Physica C: Superconductivity and its Applications
Journal Volume
315
Journal Issue
3
Pages
227-234
Date Issued
1999
Author(s)
Wu, N.L.
Du, Z.L.
Xue, Y.Y.
Rusakova, I.
Ross, D.K.
Gao, L.
Cao, Y.
Sun, Y.Y.
Chu, C.W.
Hervieu, M.
Raveau, B.
Abstract
A new family of C-free high-temperature superconducting oxides in the Ba-Ca-Cu-O system showing a Tc up to 107 K has been synthesized under high pressure. Structural analyses, based on X-ray and electron diffractions and high resolution electron microscopy, have revealed that these oxides can be represented by CaBa2Ca2Cu3O9-δ [Ca-1223-Ba] with a tetragonal subcell that has lattice constants α approximately 3.85 angstroms and c approximately 16.5 angstroms and is isostructural to Tl-1223-Ba with the Tl sites occupied mainly by Ca. These oxides have the same active block of [(CuO2)(Ca)(CuO2)(Ca)(CuO2)] but with cation mixing and substitution of Ca by Cu within the charge reservoir block [(BaO)(CaO)(BaO)]. This results in the observed variations in composition and superstructure but has only minor influence on Tc.
Type
journal article