First-principles study of the optical properties ofMgxTi1−xH2
(2009) Physical review. B, Condensed matter and materials physics — Vol. 79, n° 12, p. 125117 (2009)
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- Abstract
- Thin films of MgxTi1−x show an optical black state upon hydrogenation. We calculate the dielectric function and the optical properties of MgxTi1−xH2, x=0.5, 0.75, and 0.875 using first-principles density-functional theory. We argue that the black state is an intrinsic property of these compounds, unlike similar optical phenomena observed in other metal hydride films. The structures of MgxTi1−xH2 are represented either by simple ordered or quasirandom structures. The density of states has a broad peak at the Fermi level, composed of Ti d states; hence, both interband and intraband transitions contribute to the optical response. Ordered structures have a plasma frequency of 3 eV. The plasma frequency drops below 1 eV in disordered struc- tures, which—as a result of interband transitions—then show a low reflection and considerable absorption in the energy range of 1–6 eV, i.e., a black state.
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van Setten, M., Er, S., Brocks, G., de Groot, R. A., & de Wijs, G. A. (2009). First-principles study of the optical properties ofMgxTi1−xH2. Physical review. B, Condensed matter and materials physics, 79(12), 125117. https://doi.org/10.1103/PhysRevB.79.125117 (Original work published 2009)