Hydrogen absorption characteristics of Zr substituted Ti0.85VFe0.15Ti0.85VFe0.15 alloy

Hydrogen absorption properties of Ti0.85VFe0.15Ti0.85VFe0.15 modified by Zr substitution (5 at%) at V site are studied. The crystal structure, maximum hydrogen absorption capacity and the hydrogen desorption properties of Ti0.85V0.95Fe0.15Zr0.05Ti0.85V0.95Fe0.15Zr0.05 have been compared with those of Ti0.85VFe0.15Ti0.85VFe0.15. The alloys and the corresponding hydrides have been characterized by X-ray diffraction and Mössbauer spectroscopy. The kinetics of hydrogen uptake of both the alloys has been carried out and they are found to be comparable. The pressure–composition isotherms have been studied at room temperature and 373 K for both the alloys. Zr substituted composition is found to have better hydrogen absorption properties. Ti0.85VFe0.15Ti0.85VFe0.15 is found to absorb a maximum of 3.83 H atoms/formula unit (3.7 wt%) to form a hydride with a composition Ti0.85VFe0.15H3.83Ti0.85VFe0.15H3.83, while Ti0.85V0.95Fe0.15Zr0.05Ti0.85V0.95Fe0.15Zr0.05 absorbs a maximum of 3.74 H atoms/formula unit to form a hydride with a composition Ti0.85V0.95Fe0.15Zr0.05H3.74Ti0.85V0.95Fe0.15Zr0.05H3.74 (3.5 wt%) at room temperature. Temperature programmed desorption studies have been carried out on the saturated hydrides in order to estimate the desorption temperatures.