LIGAND HOLE INDUCED SYMMETRY MIXING OF D8 STATES IN LIXNI1-XO, AS OBSERVED IN NI 2P X-RAY ABSORPTION-SPECTROSCOPY

We report the Ni 2p XAS edges of LixNi1-xO and discuss them in terms of an atomic multiplet theory with the inclusion of an adjustable crystal and ligand field parameter 10Dq. The measurements show clearly that the charge compensating states upon Li doping are of primarily O 2p character. The change of the XAS spectra upon doping are explained by the mixing in of 1E(g) and 1A1g symmetries in the d8 part of the mainly d8L ground state of the LiNiO2 end member upon doping. The results are important for the interpretation of the electronic structure and local moments of transition metal oxides in which upon doping charge compensating states of mainly O 2p character often emerge.