Oxyhydride Nature of Rare-Earth-Based Photochromic Thin Films
S. Cornelius (TU Delft - ChemE/Materials for Energy Conversion and Storage)
Giorgio Colombi (TU Delft - ChemE/Materials for Energy Conversion and Storage)
Fahimeh Nafezarefi (TU Delft - ChemE/Materials for Energy Conversion and Storage)
Herman Schreuders (TU Delft - ChemE/Afdelingsbureau)
René Heller (Institute of Ion Beam Physics and Materials Research)
Frans Munnik (Institute of Ion Beam Physics and Materials Research)
B Dam (TU Delft - ChemE/Materials for Energy Conversion and Storage)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Thin films of rare-earth (RE)-oxygen-hydrogen compounds prepared by reactive magnetron sputtering show a unique color-neutral photochromic effect at ambient conditions. While their optical properties have been studied extensively, the understanding of the relationship between photochromism, chemical composition, and structure is limited. Here we establish a ternary RE-O-H composition-phase diagram based on chemical composition analysis by a combination of Rutherford backscattering and elastic recoil detection. The photochromic films are identified as oxyhydrides with a wide composition range described by the formula REO
x
H
3-2x
where 0.5 ≤ x ≤ 1.5. We propose an anion-disordered structure model based on the face-centered cubic unit cell where the O
2-
and H
-
anions occupy tetrahedral and octahedral interstices. The optical band gap varies continuously with the anion ratio, demonstrating the potential of band gap tuning for reversible optical switching applications.
help_outline