Rare-earth oxyhydride REO_xH_3–2x 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 bleaching time, in particular, can be reduced by an order of magnitude by increasing the O/H ratio, indirectly defined by the deposition pressure of the parent REH₂. The influence of the cation (RE = Sc, Y, Gd) under comparable deposition conditions is discussed. Our data suggest that REs of a larger ionic radius form oxyhydrides with a larger optical contrast and faster bleaching speed, hinting to a dependency of the photochromic mechanism on the anion site-hopping.

中文翻译：

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阳离子（RE = Sc，Y，Gd）和O / H阴离子比对REO _x H _{3–2 x}薄膜光致变色性能的影响

通过空气氧化反应性溅射的REH ₂二氢化物制备的稀土氧氢化物REO _x H _{3–2 x}薄膜在环境条件下显示出中性的可逆光致变色效应。目前的工作表明，O / H阴离子比率以及阳离子的选择可以在很大程度上调整光学变化的程度及其速度。特别地，通过增加O / H比可以将漂白时间缩短一个数量级，而O / H比可以直接由母体REH ₂的沉积压力来确定。讨论了阳离子（RE = Sc，Y，Gd）在可比的沉积条件下的影响。我们的数据表明，较大离子半径的RE形成具有较大光学对比度和更快漂白速度的氢氧根，暗示了光致变色机理对阴离子位点跃迁的依赖性。