Insulating fcc YH3-ô stabilized by MgH2

S.J. van der Molen, D.G. Nagengast, A.T.M. van Gogh, J. Kalkman, Ernst S. Kooij, J.H. Rector, R. Griessen

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Abstract

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.
Original languageUndefined
Pages (from-to)235116-1-235116-8
Number of pages8
JournalPhysical review B: Condensed matter and materials physics
Volume63
Issue number23
DOIs
Publication statusPublished - 2001

Keywords

  • METIS-202523
  • IR-75190

Cite this

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