UC Irvine

La2Li0.5Cu0.5O4 has been investigated by electron diffraction and high resolution electron microscopy at room temperature. Ordering between Li and Cu cations is nearly perfect within the (a, c) plane but there is disorder between Cu and Li cations along the b axis. The detection of weak reflections which violate the C centering of the Cmmm space group (initially proposed [1] for this compound), indicates that the crystal symmetry allows lattice distortions. The evolution of the structure as a function of the temperature may lead to the determination of whether the low energy singlet-triplet excitation, found in NMR/NQR studies, is coupled with lattice distortions. © 1998 Elsevier Science Ltd. All rights reserved.