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

Abstract

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.