First-principles modelling of magnesium titanium hydrides
(2010) Journal of Physics: Condensed Matter — Vol. 22, n° 7, p. 74208 (2010)
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- Abstract
- Mixing Mg with Ti leads to a hydride Mgx Ti(1−x)H2 with markedly improved (de)hydrogenation properties for x 0.8, as compared to MgH2. Optically thin films of Mgx Ti(1−x)H2 have a black appearance, which is remarkable for a hydride material. In this paper we study the structure and stability of Mgx Ti(1−x)H2, x = 0–1 by first-principles calculations at the level of density functional theory. We give evidence for a fluorite to rutile phase transition at a critical composition xc = 0.8–0.9, which correlates with the experimentally observed sharp decrease in (de)hydrogenation rates at this composition. The densities of states of Mgx Ti(1−x)H2 have a peak at the Fermi level, composed of Ti d states. Disorder in the positions of the Ti atoms easily destroys the metallic plasma, however, which suppresses the optical reflection. Interband transitions result in a featureless optical absorption over a large energy range, causing the black appearance of Mgx Ti(1−x)H2.
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Er, S., van Setten, M., de Wijs, G. A., & Brocks, G. (2010). First-principles modelling of magnesium titanium hydrides. Journal of Physics: Condensed Matter, 22(7), 74208. https://doi.org/10.1088/0953-8984/22/7/074208 (Original work published 2010)