Local Structure and L1- and L3-Edge X-ray Absorption Near Edge Structures of Middle Lanthanoid Elements (Eu, Gd, Tb, and Dy) in Their Complex Oxides

Relationship between the local structures of middle lanthanoid elements (Ln; Eu, Gd, Tb, and Dy) in their complex oxides and the characteristic features of the L₁-edge and L₃-edge X-ray absorption near edge structure (XANES) was investigated. There was a significant correlation between the pre-edge peak areas of the Ln L₁-edge or the full widths at half maximum of the white line of the Ln L₃-edge XANES spectra and the abstract physical indexes defined by bond angles formed by the middle Ln elements and the two adjacent oxygen atoms, which act as indicators of local configurational disorder of the target element. Theoretical simulation based on multiple scattering theory revealed that the pre-edge peak in the Ln L₁-edge XANES spectra originates due to the p-d hybridization that occurs above the Fermi energy. This systematic survey demonstrated a universal method to estimate the local structure of the middle Ln elements by means of XANES spectroscopy.