Structural disorder along the lithium diffusion pathway in cubically stabilized lithium manganese spinel. I. Synchrotron X-ray studies

Abstract Electron density distribution, EXAFS, and transmission electron microscope studies on stoichiometric Li(Mg 1/6 Mn 11/6 )O 4 have revealed that: (1) the structure is essentially of spinel-type with slight diffuse scattering, (2) the Li atoms are not all located at the ideal 8 a site of the Fd 3 m spinel structure, but are partially tetrahedrally distributed along the 8 a –16 c tie line, (3) the O atoms also exhibit a statistical distribution about their ideal positions and (4) the Mn 3 d electrons are squeezed out toward the open space of the coordinating octahedra with D 3 d distortion. The present results indicate the possible existence of many metastable Li positions in the structure, suggestive of complicated Li atom hopping routes in conjunction with a local distortion of neighboring atoms at least up to the second shell.