A series of single phase La1.5CaxBa1.5−xCu3Oy(0≤x≤0.50) compounds with tetragonal triple-perovskite structure is prepared. They have an incongruent melting point at 1107±1 °C which is not dependent on the amount of Ca substitution. Oxygen stoichiometry and hole concentration of these materials increase with increasing x. Thermal stability of the oxygen atom in the La1.5CaxBa1.5−xCu3Oy series is independent on the oxygen stoichiometry. For x≥ 0.25, Tc increases rapidly from 33 K to 73 K with increasing x. Tc of La1.5CaxBa1.5−xCu3Oy (CB) is always lower than that of La1.5−xCaxBa1.5Cu3Oy (LC) for a given x, suggesting that an increase in the mole fraction of the trivalent cation in these compounds would decrease its Tc.
Physica C: Superconductivity and its Applications 282-287(2), pp.767-768