Influence of Crystal Structure, Encapsulation, and Annealing on Photochromism in Nd Oxyhydride Thin Films

Thin films of rare earth metal oxyhydrides show a photochromic effect, the precise mechanism of which is yet unknown. Here, we made thin films of NdH3-2xOx and show that we can change the band gap, crystal structure, and photochromic contrast by tuning the composition (O2-:H-) via the sputtering deposition pressure. To protect these films...

Influence of Cation (RE = Sc, Y, Gd) and O/H Anion Ratio on the Photochromic Properties of REO_xH_3-2x Thin Films

Rare-earth oxyhydride REOxH3-2x thin films prepared by air-oxidation of reactively sputtered REH2 dihydrides show a color-neutral, reversible photochromic effect at ambient conditions. The present work shows that the O/H anion ratio, as well as the choice of the cation, allow to largely tune the extent of the optical change and its speed. The...

Photochromic YO_xH_y thin films examined by in situ positron annihilation spectroscopy

Doppler broadening positron annihilation spectroscopy depth profiles were collected on photochromic YO_xH_y thin films. In situ UV illumination of photochromic semiconductor YO_xH_y films leads to an increase in S-parameter and a large reduction in W-parameter, possibly caused by a change in the charge...

Structure Model for Anion-Disordered Photochromic Gadolinium Oxyhydride Thin Films

Rare-earth (RE) oxyhydride thin films prepared by reactive magnetron sputtering followed by air-oxidation show a color-neutral photochromic effect at ambient conditions within a wide composition range (REOxH3-2x where 0.5 ≤ x < 1.5). Due to the high degree of anion sublattice disorder present in these thin films, the structure models...

Oxyhydride Nature of Rare-Earth-Based Photochromic Thin Films

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....

Effect of the addition of zirconium on the photochromic properties of yttrium oxy-hydride

Thin films of yttrium oxy-hydride have interesting, reversible photochromic properties, the origin of which is poorly understood. To investigate the role of point defect mobility, we probed the effect of lattice contraction as induced by the addition of zirconium. Interestingly, we find no loss of photochromic contrast for Y _1-z...

Electronic structure and vacancy formation in photochromic yttrium oxy-hydride thin films studied by positron annihilation

In order to investigate the mechanism of the photochromic effect in yttrium oxy-hydride (YO_xH_y) thin films, Doppler broadening positron annihilation spectroscopy (PAS) was applied to probe the electronic structure and the presence of vacancies in YO_xH_y and related materials as a function of...

Photochromism of rare-earth metal-oxy-hydrides

Recently, thin films of yttrium oxy-hydride (YO_xH_y) were reported to show an unusual color-neutral photochromic effect promising for application in smart windows. Our present work demonstrates that also oxy-hydrides based on Gd, Dy, and Er have photochromic properties and crystal structures similar to YO_xH<sub...