We study the structural, optical, and electrical properties of MgzY1-z switchable mirrors upon hydrogenation. It is found that the alloys disproportionate into essentially pure YH3-δ and MgH2 with the crystal structure of YH3-δ dependent on the Mg concentration z. For 0<z<0.1, both hcp and fcc YH3-δ are observed, whereas for z>~0.1 only cubic YH3-δ is present. Interestingly, cubic YH3-δ is expanded compared to YH2, in disagreement with theoretical predictions. From optical and electrical measurements we conclude that cubic YH3-δ is a transparent insulator with properties similar to hexagonal YH3-δ. Our results are inconsistent with calculations predicting fcc YH3-δ to be metallic, but they are in good agreement with recent GW calculations on both hcp and fcc YH3. Finally, we find an increase in the effective band gap of the hydrided MgzY1-z alloys with increasing z. Possibly this is due to quantum confinement effects in the small YH3 clusters.
|Number of pages||8|
|Journal||Physical review B: Condensed matter and materials physics|
|Publication status||Published - 2001|
van der Molen, S. J., Nagengast, D. G., van Gogh, A. T. M., Kalkman, J., Kooij, E. S., Rector, J. H., & Griessen, R. (2001). Insulating fcc YH3-ô stabilized by MgH2. Physical review B: Condensed matter and materials physics, 63(23), 235116-1-235116-8. https://doi.org/10.1103/PhysRevB.63.235116