Abstract
We report preferential orientation control in photochromic gadolinium oxyhydride (GdHO) thin films deposited by a two-step process. Gadolinium hydride (GdH2-x) films were grown by reactive magnetron sputtering, followed by oxidation in air. The preferential orientation, grain size, anion concentrations and photochromic response of the films were strongly dependent on the deposition pressure. The GdHO films showed a preferential orientation along the [100] direction and exhibited photochromism when synthesized at deposition pressures of up to 5.8 Pa. The photochromic contrast was larger than 20% when the films were deposited below 2.8 Pa with a 0.22 H2/Ar flow ratio. We argue that the relation of preferential orientation and the post deposition oxidation since oxygen concentration is known to be a key parameter for photochromism in rare-earth oxyhydride thin films. The experimental observations described above were explained by the decrease of the grain size as a result of the increase of the deposition pressure of the sputtering gas, followed by a higher oxygen incorporation.
| Original language | English |
|---|---|
| Article number | 3181 |
| Journal | Molecules |
| Volume | 25 |
| Issue number | 14 |
| DOIs | |
| Publication status | Published - Jul 2020 |
Bibliographical note
Publisher Copyright:© 2020 by the authors.
Funding
Funding: The work by IFE team has received funding from the Research Council of Norway through FRINATEK Project No. 287545. Accelerator operation at Uppsala University is supported by the Swedish Research Council VR-RFI (contract No. 2017-00646_9) and the Swedish Foundation for Strategic Research (contract RIF14-0053). Author Contributions: Conceptualization, E.M.B., J.M. and S.K.; methodology, E.M.B. and J.M.; formal analysis, E.M.B., J.M., D.M., M.V.M., M.W., D.P., S.S., E.Z., S.K.; investigation, E.M.B., J.M., D.M., M.V.M., S.K.; resources, S.K.; data curation, E.M.B., D.M., M.V.M.; writing—original draft preparation, E.M.B.; writing—review and editing, E.M.B., J.M., D.M., M.V.M., M.W., D.P., S.S., E.Z., S.K.; visualization, E.M.B., D.M., M.V.M.; supervision, E.Z., S.K.; project administration, S.K.; funding acquisition, S.K. (FRINATEK Project No. 287545 from the Research Council of Norway), D.P. (infrastructural grants from VR-RFI and SSF). All authors have read and agreed to the published version of the manuscript.
| Funders | Funder number |
|---|---|
| Swedish Research Council VR-RFI | 2017-00646_9 |
| VR-RFI | |
| Stiftelsen för Strategisk Forskning | RIF14-0053 |
| Norges Forskningsråd | 287545 |
| Uppsala Universitet | |
| Institute for Future Environments, Queensland University of Technology |
Keywords
- Band gap
- Gadolinium oxyhydride
- Mixed anionmaterials
- Photochromic effect
- Preferential orientation
- Rare earthmetal oxyhydride