Annealing and quenching effects on Nd2-xCexCuO4-δ

The annealing and quenching effects are examined on Nd2-xCexCuO4-δ after it is annealed under an Ar atmosphere. From the X-ray diffraction patterns, both the quenched and furnace-cooled samples are confirmed as a single phase of Nd2CuO4 structure. The quenched samples of x=0.15 show zero resistivity at about 13 K, while zero resistance does not appear in the furnace-cooled samples. However, the DC susceptibility shows that the Meissner volume fraction is nearly the same for both samples. The results indicate that the superconductive connection between grains in the furnace-cooled samples is much weaker than that in the quenched ones. (orig.)