Hydrogen transport properties in zinc oxide

Hydrogen diffusion in single crystal and polycrystalline zinc oxide (ZnO) was investigated by deuterium diffusion and hydrogen effusion measurements. The diffusion coefficient exhibits thermally activated behavior and varies between EA=0.17EA=0.17 and 0.37 eV. Interestingly, the change in EAEA is accompanied by a variation of the diffusion prefactor by about eight orders of magnitude. This indicates that EAEA does not represent the diffusion barrier. On the other hand, the H density of states derived from effusion data is consistent with originally reported values of the diffusion activation energy of EA≈1.0eV.