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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]

The crack-free bulk hydrides of Zr Y alloys have been prepared and characterized by X-ray diffraction, optical microscopy and electron probe microanalysis to study the phase structure, microstructure and composition distribution, respectively. It was found that the as-received hydrides were composed of zirconium hydrides and yttrium hydrides mixtures. We performed thermogravimetry and simultaneous thermal desorption spectroscopy (TG/TDS) under Ar and CO 2 atmosphere to study the effect of yttrium and surface oxide layer on hydrogen desorption from zirconium hydride. The results showed that zirconium hydrides containing higher Y content tend to have higher hydrogen desorption temperatures and higher hydrogen content, suggesting that hydrogen could be retained in the hydride matrix by alloying with yttrium. X-ray diffraction indicated that an oxide layer was formed on the surface of the metal hydrides under CO 2 atmosphere, and yttrium could stabilize t-ZrO 2 phase in the oxide layer, thus inhibiting hydrogen desorption from the metal hydrides at the reactor working temperature. [ABSTRACT FROM AUTHOR]