Correlating chemical composition and optical properties of photochromic rare-earth oxyhydrides using ion beam analysis

Aðalsteinsson, Sigurbjörn M.; Moro, Marcos V.; Moldarev, Dmitrii; Droulias, Sotirios A.; Wolff, Max; Primetzhofer, Daniel

doi:10.1016/j.nimb.2020.09.016

Cited by 24 publications

(23 citation statements)

References 34 publications

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“…Specifically, many authors use the low-intensity (101) reflection to distinguish between Fm 3̅ m and P 4/ nmm since it only appears for the latter space group. 7 , 8 , 25 However, A∂̅alsteinsson et al 11 did not find this reflection for their NdH 3–2 x O x films and assigned no space group. Therefore, it is unclear whether Nd oxyhydride thin films exhibit a tetragonal crystal structure as their powdered counterparts do.…”

Section: Resultsmentioning

confidence: 89%

“…Here, we investigate the structural properties of NdH 3–2 x O x thin films and their photochromic performance. While photochromism in Nd-based oxyhydrides was reported earlier, 11 a complete optical and structural analysis has been lacking so far. Rare earth oxyhydrides based on Nd are of particular interest because they show a high H – conductivity, 7 have a large RE cation, and have sometimes been described as anion-ordered with a tetragonal crystal structure.…”

Section: Introductionmentioning

confidence: 97%

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

et al. 2022

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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 NdH 3–2 x O x and show that we can change the band gap, crystal structure, and photochromic contrast by tuning the composition (O 2– :H – ) via the sputtering deposition pressure. To protect these films from rapid oxidation, we add a thin ALD coating of Al 2 O 3 , which increases the lifetime of the films from 1 day to several months. Encapsulation of the films also influences photochromic bleaching, changing the time dependency from first-order kinetics. As well, the partial annealing which occurs during the ALD process results in a dramatically slower bleaching speed, revealing the importance of defects for the reversibility (bleaching speed) of photochromism.

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Section: Resultsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 97%

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

et al. 2022

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“…Ref. [3] for a similar system). Light impurities (C and F) originating from the deposition process are found for all samples (in sum ≤ 5-7 at.%).…”

Section: Methodsmentioning

confidence: 96%

“…Recently, it was found that oxygen-containing rare-earth metal hydride thin films (REHO) change their optical transmission under illumination with visible light at ambient conditions [1][2][3][4][5] , attracting the attention of the scientific community for their potential applications in next generation of photochromic coatings (smart-windows) and optoelectronic devices (gas sensors) [6][7][8] . Transparent and photochromic REHO films are produced by either reactive Armagnetron sputtering [9] or reactive electron-beam evaporation [10] of a rare-earth metal hydride (REH2) onto a transparent substrate, followed by oxidation in air.…”

Section: Introductionmentioning

confidence: 99%

Photochromic Response of Encapsulated Oxygen‐Containing Yttrium Hydride Thin Films

Moro

Aðalsteinsson

Tran

et al. 2021

Physica Rapid Research Ltrs

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Photochromic oxygen-containing yttrium-hydride thin films are synthesized by argonmagnetron sputtering on microscope slides. Some of them are encapsulated with a thin, transparent and non-photochromic diffusion-barrier layer of either Al2O3 or Si3N4. Ion beambased methods prove that these protective diffusion barriers are stable and free from pinholes, with thicknesses of only a few tens of nanometers. Optical spectrophotometry reveals that the photochromic response and relaxation time for bothprotected and unprotectedsamples are almost identical. Ageing effects in the unprotected films lead to degradation of the photochromic performance (self-delamination) while the photochromic response for the encapsulated films is stable. Our results show that the environment does not play a decisive role for the photochromic process and encapsulation of oxygen containing rare-earth hydride films with transparent and non-organic thin diffusion barrier layers provides long-time stability of the films, mandatory for applications as photochromic coatings on e.g., smart windows.

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“…Oxygen-containing metalÀhydride thin films (MEHO, ME ¼ Sc, Y, Nd, Gd, Dy, and Er) are known to be capable of a reversible, color-neutral change in optical transmission in the visible range when illuminated with photons of energies larger than the bandgap of the material, that is, starting from the near-UV part of the visible spectrum. [1][2][3] This optical response, referred to as photochromism, makes these material systems attractive for potential technological applications in, for example, smart sensors and self-regulating smart-window coatings. [4] The vast majority of the photochromic MEHO coatings reported have been produced by reactive Ar magnetron sputtering of metallic rare earths in an Ar:H 2 environment, followed by oxidation of the films when exposed to air.…”

Section: Introductionmentioning

confidence: 99%

Photochromism in Isotopically Labeled Oxygen‐Containing Yttrium−Hydride and Deuteride Thin‐Film Systems

Moro

Aðalsteinsson

Moldarev

et al. 2021

Physica Rapid Research Ltrs

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Photochromic mono‐ and bilayered thin films of oxygen‐containing isotope‐labeled yttrium−hydride (i.e., protium and deuterium) are synthesized via reactive Ar sputtering. Selected samples are encapsulated with transparent diffusion barriers. Combining depth‐resolved nondestructive ion beam‐based techniques for composition and optical spectrophotometry, material mobility in the samples during illumination and over time is investigated. The results reveal that deuteride thin films exhibit a strong photochromic response equivalent to hydrogenated systems. No evidence of long‐distance light‐induced hydrogen mobility or thermal diffusion is found. The findings thus show that photochromism is not connected to long‐distance material transport. The observations for encapsulated samples also exclude direct material exchange with the environment and any environmental influence on material mobility.

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Correlating chemical composition and optical properties of photochromic rare-earth oxyhydrides using ion beam analysis

Cited by 24 publications

References 34 publications

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

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

Photochromic Response of Encapsulated Oxygen‐Containing Yttrium Hydride Thin Films

Photochromism in Isotopically Labeled Oxygen‐Containing Yttrium−Hydride and Deuteride Thin‐Film Systems

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