TY - UNPB
T1 - Finite temperature effects on the X-ray absorption spectra of crystalline aluminas from first principles
AU - Harper, Angela F.
AU - Monserrat, Bartomeu
AU - Morris, Andrew J.
PY - 2022/6/21
Y1 - 2022/6/21
N2 - 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
AB - 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
KW - cond-mat.mtrl-sci
U2 - 10.48550/arXiv.2206.10448
DO - 10.48550/arXiv.2206.10448
M3 - Preprint
BT - Finite temperature effects on the X-ray absorption spectra of crystalline aluminas from first principles
PB - arXiv
ER -