TEMPERATURE-DEPENDENCE STUDY OF YMN2D4.5 BY MEANS OF NEUTRON POWDER DIFFRACTION

The deuteride YMn2D4.5, has been studied by means of temperature depen dent neutron diffraction analysis. A magnetic transition is observed a t 398 K on heating and 378 K on cooling. The transition involves both rhombohedral splitting of the diffraction lines of the high temperatur e cubic phase and appearance of superstructure lines. Crystallographic and magnetic parameters have been obtained from the refinement of the neutron diffraction patterns above, and below the transition. It show s that the transition involves both deuterium ordering and magnetic or dering. The competition which occurs in this compound between deuteriu m ordering and magnetic interactions is discussed and compared with ot her systems. (C) 1998 Elsevier Science S.A.