RELATION BETWEEN T-C AND THE DEFECT STRUCTURE OF NEODYMIUM CERIUM CUPRITE ND2-XCEXCUO4-Y

Neutron powder diffraction has been used to study the defect structure of neodymium cerium cuprite Nd2-xCexCuO4+/-y (x=0.15). It has been sh own that in addition to oxygen vacancies, O2 sites in superconducting samples may also contain a small quantity of implanted oxygen atoms po sitioned between copper ions and neodymium/cerium, which control the e lectrical charge in the Cu-O planes. The oxygen distribution among cry stal lattice sites in Nd2-xCexCuO4+/y (x=0.15) was determined, the ave rage charge of the copper ions was calculated by the method of valence sums, and a correlation was established between the charge of the cop per-oxygen plane and T-c. (C) 1998 American Institute of Physics.