Oxyhydride Nature of Rare-Earth-Based Photochromic Thin Films

Journal article (2019)

Authors

S. Cornelius ChemE/Materials for Energy Conversion and Storage - AS
G. Colombi ChemE/Materials for Energy Conversion and Storage - AS
F. Nafezarefi ChemE/Materials for Energy Conversion and Storage - AS
H. Schreuders ChemE/Afdelingsbureau
R. Heller Institute of Ion Beam Physics and Materials Research
Frans Munnik Institute of Ion Beam Physics and Materials Research
B. Dam ChemE/Materials for Energy Conversion and Storage - AS
Research Group
ChemE/Materials for Energy Conversion and Storage (AS) (TU Delft)
Copyright: © 2019 S. Cornelius, G. Colombi, F. Nafezarefi, H. Schreuders, R. Heller, Frans Munnik, B. Dam
DOI: https://doi.org/10.1021/acs.jpclett.9b00088
More Info
expand_more

Published Date

2019

Language

English

Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Materials for Energy Conversion and Storage

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.