Neutron powder diffraction study on Li1.8Na0.2MgCl4

The crystal structure of inverse spinel-type (space group Fd3m, Z = 8), quaternary lithium chloride Li 1.8 Na 0.2 MgCl 4 has been determined by neutron powder diffraction methods (a = 1044.16(7) pm, 114 reflections, R exp = 5.23%). The sodium ions are solely placed at the octahedral 16d site together with the Mg 2+ and a part of the Li + ions. These results are in agreement with analogous studies on the manganese compound (Lutz et al., 1989) but being in contradiction with the results of 6 Li and 7 Li MAS NMR experiments (Nagel et al., 2002). The reason of this discrepancy is discussed.