THE ELECTRONIC-STRUCTURE OF KNBO3 - AN XPS AND XAS STUDY

The electronic structure of orthorhombic potassium niobate has been studied with a particular focus on empty electronic states. Occupied electronic states were analysed by x-ray photoelectron spectroscopy. Empty electronic states were probed by x-ray absorption spectroscopy at the oxygen K edge (531 eV), the niobium L1 (2698 eV), L2 (2465 eV), and L3 (2371 eV) edges, and the potassium K (3608 eV) edge. Absorption experiments are interpreted in terms of orbital hybridizations using self-consistent tight-binding calculations. O K-edge structures are related to hybridizations of O 2p orbitals with Nb 4d, 5p, and 5s orbitals respectively. Nb L edges reflect the (t2g, e(g)) degeneracy lift Of Nb 4d orbitals placed in the NbO6 environment. The delocalization of Nb 4d e(g) states is not found to be significantly larger than the delocalization of Nb t2g states.