POSSIBLE COMPETITIVE ELECTRON-LIKE AND HOLE-LIKE CONDUCTION IN THE REVIVED ND1.82CE0.18CUOY SUPERCONDUCTORS

Thermoelectric power (S) studies on the nominally electron-doped Nd1.8 2-zSrzCe0.18CuOy (NSCCO) superconductor system in the temperature rang e 35 K to 250 K are reported here, S of the reduced z = 0.09 sample ha s negative sign, indicating electron conduction, and has small magnitu de, showing high metallicity. The sign of S for the z = 0.18 sample ho wever shows a cross-over below 75 K, from negative to positive, confli cting perhaps with electronic conduction, This sample on oxygenation e xhibits broadened positive peak and apparently gets carrier concentrat ion enhanced. There is seemingly a competition between electron and ho le-like conduction in these co-doped compounds also.