Influence of oxide layer on hydrogen desorption from zirconium hydride

Abstract: Hydrogen desorption from zirconium hydride with hydrogen content of 1.95 H/Zr in He and He–5%O2 atmospheres was studied by thermal desorption spectroscopy (TDS). The morphology, structure and valence states of the oxide layer formed on the surface of zirconium hydride were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that hydrogen desorption is retarded in the presence of oxygen. Heating in He leads to a large desorption range starting at 500°C while heating in He–5%O2 atmosphere delays decomposition to relatively higher temperature of 525°C. A protective oxide layer composed of monoclinic ZrO2 and small amount of tetragonal ZrO1.88, which acts as a very effective diffusion barrier. The O–H bond was observed in the oxide layer, which is beneficial to fix hydrogen atoms and prevent hydrogen diffusion. [Copyright &y& Elsevier]