Comparison of electronic structure of LiInO2 with NaInO2

Electronic structure of NaCl type LiInO2 was compared experimentally and theoretically with that of alpha-NaFeO2 type NaInO2 to clarify the influences of Li-In direct interaction peculiar to LiInO2. Ultraviolet-visible diffuse reflectance spectrum of LiInO2, with the onset of absorption at 3.7 eV, was rather more simple than that of NaInO2 accompanied by two small peaks in the band gap of 3.7 eV. Discrete variational-Xalpha calculations for the [Li10In9O44](51-) and [Na7In12O44](45-) model clusters depicted well the features of absorption spectra of LiInO2 and alpha-NaInO2, respectively. The calculations also revealed that higher valence bands of LiInO2 and NaInO2 were dominated, respectively, by the Li 2s-In 5s bonding orbital with a large overlap population and the Na 3s,p-O 2p bonding orbital with a small overlap population, however, lower conduction bands in both LiInO2 and NaInO2 were formed by the In 5s-O 2p antibonding orbital. The experimental valence band spectrum of LiInO2, simply peaked at similar to4 eV below the valence band maximum, can be ascribed to overlapping of the Li 2s-In 5s bonding orbital with the In 5p-O 2p bonding orbital at around -3 eV in the density of states. (C) 2003 Elsevier B.V. All rights reserved.