In the superconductive lanthanum compounds La2-xAxCuO4 (A=Sr, Ca, Ba), divalent ions were substituted with monovalent Na, K and divalent Pb. Only the substitution with Na resulted in a superconductivity, and the critical temperature (Tc) is found to be 22.2K at the composition at La1.5Na0.5CuO4 reacted at temperatures between 880 and 890°C. In another superconductive compound LaBa2Cu3O7-y which has the same structure as YBa2Cu3O7-y, divalent Ba ions were partially substituted with Ca2+ and Sr2+. In the compound LaBaSrCu3O7-y Tc deteriorates and two superconductive phases appear. On the contrary, in the compound LaBaCaCu3O7-y metalic behavior and a sharp transition in resistivity are found, i.e., its transition width (ΔT) is within 3K. Further, Tc is not much influenced by the sintering temperatures between 890 and 1, 050°C, and is reproducibly settled in between 74.7K and 77.4K. These results should be compared with those obtained in LaBa2Cu3O7-y, in which Tc largely depended on sintering temperature and T amounts to 13.4K.
