AN INVESTIGATION ABOUT THE IMPROVEMENT OF T(C) FOR THE N-TYPE SUPERCONDUCTOR ND2-XCEXCUO4

Nd2-xCexCuO4(x = 0.12 to 0.18)with T(onset) = 17 to 26 K is synthesized from the nominal composition of Nd2-xCexCuO4 + nSrCuO2 (+ nCaCuO2) (n = 1, 2) under standard conditions without high pressure treatment. The sintering temperature, atmosphere, and synthetic procedure are important for the superconductivity of Nd2-xCexCuO4. It is difficult to build up n blocks of SrCuO2, CaCuO2, or CdCuO2 on Nd2-xCexCuO4 so as to add CuO2 layers. In addition, the crystal structure and electrical resistance of Nd2-xCexCuO4 are studied.