F-19 NMR-STUDY OF SUPERCONDUCTIVE AND NONSUPERCONDUCTIVE ND2CUO4-XFY

We have synthesized superconductive and nonsuperconductive samples of the n-type high-T-c superconducting system Nd2CuO4-xFy from the same b atch. They give very similar normal state F-19 NMR results, with decre asing spin-lattice relaxation time (T-1) and the spin-spin relaxation time (T-2E) and increasing negative line shift on decreasing temperatu re. Our results seem to indicate that the fluorine is more likely to b e substituted into the O(2) sites between the Nd planes in this system .