TEM observation and Hall measurements on superconductive Nd2CuO4−xFx

Abstract We report the structural and transport properties of polycrystalline superconductive Nd 2 CuO 4− x F x samples. Chemical analysis shows that the fluorine content of the samples decreases to about 85% of the nominal content after sintering at 1100°C. For the Nd 2 CuO 3.8 F 0.2 sample ( T c,on =27 K and T c,zero =20 K), TEM observation indicates that there are no evidences for the existence of any type of structural modulations. For each sample with x in the range from 0.1 to 0.3, the Hall coefficient ( R H ) is found to be negative in the temperature range between 30 and 275 K. Moreover, the temperature dependence of R H seems to be similar to that of the n-type superconductor, Nd 2− y Ce y CuO 4 . This suggests that electrons are the dominant charge carriers in Nd 2 CuO 4− x F x at least in the normal state.