Abstract
Studies of newly discovered cuprates and cuprate superconductors containing carbonate groups were reviewed. Carbonate groups (CO3), CuOx and alkali-earth elements (Sr, Ba) comprised new block layers of [(Sr, Ba)2(C, Cu)Ox]. Combination of the block layers containing CO3 and previously known block layers (oxygen-deficient metal layers or fluorite layers) brought new compounds and superconductors. Superconducting transition temperatures of (Sr1-xBax)2Cu1+yO2+2y+d(CO3)1-y' (Y0.5Ca0.5)0.95 Sr2.05Cu2.4Ox(CO3)0.6 and (Y0.73Ce0.27)2Sr2Cu2.65Ox(CO3)0.35 were around 40, 68 and 17 K, respectively.
