Large Polaron Conduction, Photoconductivity, and Photochromism in GdO_xH_3−2x Oxyhydride Thin Films

At ambient conditions, rare-earth oxyhydride thin films show reversible photochromism and photoconductivity, while their mechanism and relation are still unclear. In this work, this question is explored with in situ time-resolved measurements of both optical and transport properties of Gd-based oxyhydride thin films. It is found that p-type...

Photochromic samarium oxyhydride thin films

Photochromism has been reported for several rare-earth (RE) metal oxyhydride thin films and is characterized by a reversible darkening of the sample when exposed to light with energy greater than its optical bandgap. Here, we extend the range of known photochromic RE-oxyhydrides to include samarium oxyhydrides. These SmH3−2xOx thin films are...

Exploring Multi-Anion Chemistry in Yttrium Oxyhydrides: Solid-State NMR Studies and DFT Calculations

Rare earth oxyhydrides REO_xH_(3-2x), with RE = Y, Sc, or Gd and a cationic FCC lattice, are reversibly photochromic in nature. It is known that structural details and anion (O^2-:H^-) composition dictate the efficiency of the photochromic behavior. The mechanism behind the photochromism is, however,...

Chasing H- in Rare-earth Metal Oxyhydride Thin Films

Rare-earth metal oxyhydride thin films show a photochromic effect, where their transparency decreases (reversibly) with exposure to light with energy greater than its optical band gap. The precise underlying mechanism behind this effect is unknown, but is investigated in this thesis by using techniques such as muon spin relaxation, or materials...

Formation of vacancies and metallic-like domains in photochromic rare-earth oxyhydride thin films studied by in-situ illumination positron annihilation spectroscopy

Rare-earth (RE) oxyhydride thin films show a color-neutral, reversible photochromic effect at ambient conditions. The origin of the photochromism is the topic of current investigations. Here, we investigated the lattice defects, electronic structure, and crystal structure of photochromic YHxOy and GdHxOy thin films deposited by magnetron...

Energy, metastability, and optical properties of anion-disordered R Ox H3-2x (R= Y, La) oxyhydrides: A computational study

In this paper, we investigate by ab initio DFT how the O:H ratio influences the formation and lattice energy, metastability, and optical properties of Y and La anion-disordered ROxH3-2x oxyhydrides. To achieve this, a set of special quasirandom structures (SQS) is introduced to model anion-disorder along the whole RH3-R2O3 composition line. A...

Aliovalent Calcium Doping of Yttrium Oxyhydride Thin Films and Implications for Photochromism

To develop an understanding of the photochromic effect in rare-earth metal oxyhydride thin films (REH3-2xOx, here RE = Y), we explore the aliovalent doping of the RE cation. We prepared Ca-doped yttrium oxyhydride thin films ((CazY1-z)HxOy) by reactive magnetron cosputtering with Ca doping concentrations between 0 and 36 at. %. All of the...

Erratum to: Aliovalent Calcium Doping of Yttrium Oxyhydride Thin Films and Implications for Photochromism (The Journal of Physical Chemistry C (2022) 126:34 (14742−14749) DOI:10.1021/acs.jpcc.2c04456)

The energy axes of the RBS and ERD data (contained in Figures 2a,b,d,e, and S4) were originally underestimated, and the corrected figures appear below and in the Supporting Information. The change is in the conversion from raw data to the energy scale, which was initially converted incorrectly. The rescaled x-axis does not change the data...

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...

Structural properties and anion dynamics of yttrium dihydride and photochromic oxyhydride thin films examined by in situ μ+SR

Thin films of rare-earth metal oxyhydrides, such as yttrium oxyhydrides (YH3-2xOx), show a photochromic effect where the transparency of the films decreases reversibly upon exposure to UV light. However, the exact mechanism behind this effect is unknown. In this paper, we describe the behavior of YH3-2xOx thin films, with different O2-:H-...

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...

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...