HIGH-TEMPERATURE ANOMALIES OF THE ELECTRICAL-RESISTIVITY AND THERMOELECTRIC-POWER IN LA(2-X)R(X)CUO(4) (R=Y AND FE, X=0.0 AND 0.05)

Samples of Lap(2-x)R(x)CuO(4)(R = Y and Fe; x = 0.0 and 0.05) were pre pared by the usual ceramic method. X-ray diffraction studies indicated the presence of a single phase. The samples were studied by different ial scanning, calorimetry, electrical resistivity and thermoelectric p ower. An intimate relation between the electrical properties and the d ifferent transitions in La2CuO4 was found. The partial substitution of Y or Fe for La in La2CuO4 has a slight effect on the transition tempe ratures; it was found to inhibit the phase recombination supposed in t he unsubstituted sample at 410 K. Finally the effect of substitution o f Y or Fe was found to increase both the electrical resistivity and th ermoelectric power markedly.