Interrupted thermal desorption of TiH2

Structural changes of commercial TiH2 were studied using interrupted temperature desorption spectroscopy and X-ray diffraction techniques to understand the mechanism of its degradation under non-equilibrium conditions. Rapid cooling on different stages of temperature-programmed heating allowed to study the intermediate phase compositions that evolve upon cooling from the high-temperature phase βTi(H). The phase transformation sequence is described as a number of consecutive reactions corresponding to the observed desorption peaks. Phases δTiH2−x, γTiH, and the solid solution αTi(H) were found to be intermediates in the ɛTiH2 → αTi transformation when the latter is interrupted. Additional evidence for the thermodynamic stability of γTiH is given.