Surface characterizations of TiH2 powders before and after dehydrogenation

The oxide film of TiH2 and HDH-Ti powder are investigated using X-ray photoelectron spectroscopy (XPS). The XPS depth profiles indicate that there exists mainly Ti2+, Ti3+, Ti4+ and Ti0 on TiH2 and HDH-Ti surface. The intensities of Ti 2p decrease for Ti4+, first increase and then decrease for Ti3+ and Ti2+, and increase all the time for Ti0 in the surface layer of TiH2 and HDH-Ti with the sputtering depth increasing. The relative fractions of TiO2, Ti2O3 and TiO for the Ti 2p of TiH2 and HDH-Ti first decrease and then slow down with the sputtering depth increasing. Meanwhile, the relative fractions of TiO2 and TiO of HDH-Ti are lower than that of TiH2 after the sputtering depth of about 5 nm, and the fraction of Ti2O3 of HDH-Ti is always lower that of TiH2. In addition, the decrease of Ti2O3 is much pronounced, followed by TiO2 and TiO before and after dehydrogenation when the sputtering depth is more than 5 nm. The XPS depth profiles and calculation results suggest that the release of H atoms removes the part of oxygen on TiH2 surface, which results in the thinner oxide layer and low oxygen content of HDH-Ti powder.