We have synthesized a new family of oxycarbonate compounds (Ln,Ca) (Sr,Ba)2(C,Cu)Cu2O7-δ (Ln: rare-earth metals) with a so-called "CO3-1212" structure. Two kinds of single phase in the general formula Er0.5Ca0.5Sr2-xBaxCu3-y CyO7-δ with (x,y)=(0.6, 0.5) and (1.3, 0.4) were prepared at different CO2 partial pressures. The former compound shows a superconducting transition at about 45 K, and the latter has Tc up to 80 K. This rise in Tc may come from the increase of carrier density because of the decrease of carbon content. We have also studied the Ln-dependence, and it is revealed that most of the compounds Ln0.5Ca0.5Sr0.7Ba1.3Cu2.6C0.4O7-δ show the same results, except for Ln=Ce and Tb, which did not construct the structure, and also Ln=Pr, which shows suppressed superconductivity with Tc of 30 K.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering