Estimating Hybridization of Transition Metal and Oxygen States in Perovskites from O K-edge X-ray Absorption Spectroscopy
Journal Article - Open Access
Department of Mechanical Engineering, Massachusetts Institute of Technology Cambridge United States
Pagination or Media Count:
The interaction between the transition metal 3d and the oxygen 2p statesvia hybridization underpins many of the phenomena in transition metal oxide materials.We report the empirical trend of this interaction using the pre-edge feature of the O KedgeX-ray absorption spectrum. Our assessment method is built on the dipoleapproximation and the configuration interaction between the transition metal 3d and theoxygen 2p states. We found that hybridization increases with the number of 3d electrons,consistent with the expected electronegativity trend. We support this analysis withdensity functional calculations, which reveal a systematic increase in the transition metal3d and the oxygen 2p state mixing with increasing 3d-electron number. Oxidation of thetransition metal was also found to increase hybridization, which we believe reflects thereduced transition metal 3d and oxygen 2p energy difference, causing increased covalency. We compare the analysis from thesurface-sensitive electron-yield and the bulk-sensitive fluorescence-yield spectra, revealing that either method can be used tostudy the hybridization trend. We finally compare and discuss the influence of the lanthanide ions and the influence of thecovalency on oxygen electrocatalysis. Our study describes an efficient and simple approach to understand the hybridization trendin transition metal oxides, which has considerable implications for electrochemical energy conversion processes.
- Physical Chemistry
- Atomic and Molecular Physics and Spectroscopy