Thermodynamics and structural aspects of hydrogen absorption in Zr1-xCrxFe2Zr1-xCrxFe2 alloys

The hydrogen storage properties of Zr1-xCrxFe2Zr1-xCrxFe2 (x=0.2x=0.2, 0.3, 0.4, 0.5) alloys have been obtained in the pressure and temperature range of 0.5⩽P⩽60bar and 303K⩽T⩽373K. The alloys have been characterized by XRD and SEM. The results show that all the alloys were having C14 laves phase hexagonal structure. The substitution of Cr in Zr site leads to the contraction of their lattice. The PP–C–TT isotherms of the alloys showed the existence of αα, α+βα+β, and ββ regions. The maximum hydrogen intake capacity is around 3.131 H/f.u. at 303 K and at 48 bar pressure for Zr0.8Cr0.2Fe2Zr0.8Cr0.2Fe2 alloy. The average relative partial molar enthalpy and entropy of hydrogen at plateau region have been calculated for all the alloys. The presence of αα, α+βα+β, and ββ region as seen in PP–C isotherm has been confirmed by the variation of thermodynamical parameters with hydrogen content.