CRYSTAL-STRUCTURE REFINEMENT OF ND2-XCEXCUO4 (X = 0.05-0.30) BY X-RAY (295-K) AND NEUTRON (1.5-K) POWDER DIFFRACTION

The lattice constants and the atomic positional and thermal parameters of tetragonal Nd2-xCexCuO4 were refined from X-ray (295 K) and neutron (1.5 K) powder data. A rare earth oxide phase was detected for x 0.20. Whereas the a-axis remains constant over the whole range of composition, a pronounced decrease of the c-axis with increasing amount of cerium is observed at both temperatures. The cell constants at 1.5 K are slightly shorter (a = 94224(3), c = 12.0603(1)) than at 295 K (a = 3.9457(2), c = 12.0764(9)) for x = 0.15. No deformation to lower symmetry was detected at 1.5 K. © 1990.