The transport of H through a plasma-enhanced chemical vapor deposited oxide film on a Pd substrate was investigated by using the time-lag method and alternating current impedance spectroscopy. Experiments were carried out on bilayer specimens by applying a constant cathodic current density of 80A/cm2 to the Pd side and anodic potentials, ranging from -300 to 300mV, to the oxide side. Alternating-current impedance measurements were performed on the oxide side before and after permeation. The diffusivity of H in the oxide film was deduced, from the time lag, to be equal to between 3.9 x 10-14 and 5.2 x 10-14cm2/s; for anodic potentials ranging from -300 to 300mV. The relatively low value of H diffusivity in the oxide was explained in terms of H trapping in the film. The injection of H into the oxide film greatly increased the capacitance of the oxide film. It was suggested that trapped H formed deep donor levels in the band-gap of the oxide film.

Hydrogen Permeation through PECVD (Plasma-Enhanced Chemical Vapor Deposition) TiO2 Film on Pd by the Time Lag Method. Pyun, S.I., Park, J.W., Yoon, Y.G.: Journal of Alloys and Compounds, 1995, 231, 315-20