Abstract
Electrical resistivity measurements have been carried out on the La 2-x CuO 4-δ and (La 2-x Ca x )CuO 4-δ samples prepared at various sintering temperatures and cooling rates in air, oxygen or argon atmosphere in order to check the systematic variation of superconducting transition temperature (T c ), normal state electrical resistivity, and oxygen stoichiometry. Correlation between these physical properties and oxygen stoichiometric parameter δ clearly indicates the important role of oxygen on the superconductivity of these systems. © 1988 Elsevier Science Publishers B.V.