Oxygen mobility in yttrium hydride films studied by isotopic labelling

The photochromic properties of oxygen-containing yttrium hydride thin films are directly dependent on the oxygen concentration in the material. We use 16O/18O labelling to study oxidation of YH2 films. Oxygen penetrates the film through grain boundaries and intercolumnar voids oxidising the whole film thickness, without pronounced surface oxidation or self-passivation. Once oxidised, the mobility of oxygen in the films is low and no detectable changes in chemical composition of 18O-labeled YHO films is found under illumination