Journal Article

PUBDB-2026-01046

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Impact of hydrogen concentration on the local structure of yttrium in photochromic yttrium oxyhydride

Arslan, H.Extern* ; Kuzmin, A.Extern* ; Pudza, I.Extern* ; Karazhanov, S. (Corresponding author)Extern*

2026
Elsevier Ltd. Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.mtchem.2026.103550  doi:10.3204/PUBDB-2026-01046

Abstract: We report a systematic study of the relationship between structure and photochromic activity in yttrium oxyhydride (YHO) thin films deposited by DC magnetron sputtering under different ratios of ionization gas (Ar) and reactant gas (H$_2$) flows. The best photochromic performance was observed for intermediate ratios Ar/H$_2$ ≈ 9-12. Decreasing the Ar/H$_2$ ratio to about 5 promotes film growth with a (200) texture and suppresses photochromic activity. On the contrary, increasing the Ar/H$_2$ ratio to about 19 results in a dark-colored film without photochromic activity, exhibiting a metallic-like environment similar to Y foil or yttrium hydride. The local atomic structure and oxidation state of yttrium cations were probed using Y K-edge X-ray absorption spectroscopy. No shift in the absorption edge position was found under different deposition and illumination conditions, indicating an average Y$^{2.5+}$ oxidation state in YHO films. Analysis of extended X-ray absorption fine structure confirms that, while yttrium ions are on average arranged on a face-centred cubic lattice, local structural distortions induce a splitting of the second coordination shell of yttrium, well visible in both transparent and dark film states. These findings suggest that photochromism in YHO is not driven by changes in the average electronic structure of yttrium ions. The previously reported reduction of the yttrium charge may instead result from light-induced anion vacancy formation and defect migration.

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Contributing Institute(s):

1. FS DOOR-User (FS DOOR-User)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
2. SWEB - Smart Windows for Zero Energy Buildings (101087367) (101087367)
3. FS-Proposal: I-20230822 EC (I-20230822-EC) (I-20230822-EC)

Experiment(s):

1. PETRA Beamline P65 (PETRA III)

Appears in the scientific report 2026

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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