Structural phase transition of the spinel-type oxide LiMn2O4

The crystal structure of the low-temperature (LT) form of spinel-type LiMn2O4, has been studied by neutron and X-ray powder diffraction as well as electron diffraction. Reflections of the LT phase in its neutron and X-ray diffraction patterns were indexed on the basis of not a tetragonal unit cell but roughly an orthorhombic one (space group Fddd) with lattice parameters a = 8.2797(2), b = 8.2444(3) and c = 8.1981(2) Angstrom. However, the presence of extra reflections which cannot be indexed with this unit cell shows that the actual lattice parameters ale different from the above ones. Superlattice reflections, which were missing in powder diffraction patterns, with tripled periodicity were observed in election diffraction patterns of the LT phase. (C) 1998 Elsevier Science B.V. All rights reserved.