Superconductivity in Hole-Doped La1.8-xEu0.2CaxCuO4 with the Nd2CuO4-Type Structure

We have succeeded in synthesizing hole-doped bulk superconductors of La1.8-xEu0.2CaxCuO4 (x = 0.05 and 0.10) with the Nd2CuO4-type structure by means of the structural transformation at low temperatures from the K2NiF4-type structure via the Nd4Cu2O7-type structure. Superconductivity has appeared through the removal of excess oxygen by the reduction annealing in vacuum. Values of the superconducting transition temperature, Tc, are 13 and 6 K for x = 0.05 and 0.10, respectively. These values are smaller than those of T’-La1.8-xEu0.2SrxCuO4.