International Conference on METALS IN SOLUTION
J. Phys. IV France 01 (1991) C5-339-C5-344
THE STRUCTURE OF Yb (ND3)5.7C. NÖLDEKE1, P. DAMAY2, W. PRESS1, F. LECLERCQ2, W. LIPPIK1 and M. FOUKANI2
1 Institut für Experimentalphysik der Universität Kiel, Leibnizstrasse 19, D-2300 Kiel, Germany
2 URA 253 du CNRS, HEI, 13 rue de Toul, F-59046 Lille cedex, France
Neutron powder diffraction was performed on five Yb(ND3)x samples prepared with x = 5.5, 5.7, 5.9 6.0 and 6.3. Two different low temperature (2 K) structures are observed ; one (i) mainly showing peaks of a bcc lattice with a0 = 9.076 Å but also weak sc peaks, the other (ii) presenting bcc peaks only with a0 = 9.111 Å. At 17 K the sc peaks in (i) vanish, which indicates the presence of an order- disorder phase transition. For the orientationally disordered structure (ii), Yb(ND3)5.7, showing more disorder at low temperature, a structure refinement with cubic harmonic functions is given.
© EDP Sciences 1991