Finite temperature effects on the X-ray absorption spectra of crystalline aluminas from first principles

Angela F. Harper, Bartomeu Monserrat, Andrew J. Morris

Research output: Working paper/PreprintPreprint

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Abstract

X-ray Absorption spectroscopy (XAS) is a high-resolution probe of the electronic density of states within solid-state materials. By including phonon-assisted transitions within plane-wave density-functional theory methods of calculating the XAS we obtain the Al K-edge XAS at 300 K for two crystalline phases of alumina (Al2O3). From these finite-temperature spectra, we reproduce the pre-edge peak for the α-Al2O3 phase, which arises from a mixed s-p state that is not visible at the static-lattice level of approximation. In addition, we calculate the finite-temperature XAS for γ-Al2O3, which has not previously been reported, and find that the fully ordered spinel-based model of γ-Al2O3 describes two out of the three experimental transitions seen in the Al K-edge. We observe that the third peak in the calculated γ-Al2O3 spectrum arises from transitions in AlO6 octahedral coordination environments from Al 1s to delocalized d-like states. Finally, we propose this letter as a basis for future applications of finite-temperature XAS from first principles, as the methods used are fully generalizable to any atom and edge, beyond the Al K-edge
Original languageEnglish
PublisherarXiv
DOIs
Publication statusPublished - 21 Jun 2022

Keywords

  • cond-mat.mtrl-sci

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