Effect of La-content on the hydrogenation properties of the Ce1−xLaxNi3Cr2 (x=0.2, 0.4, 0.6, 0.8, 1) alloys

The effect of partial substitution of Ce by La in CeNi3Cr2 hydrogen storage alloy has been systematically investigated. All intermetallic compounds Ce1-xLaxNi3Cr2 (x = 0.2, 0.4, 0.6, 0.8, 1) synthesized by arc melting method are well characterized by the means of XRD and SEM. XRD results show that all the alloys are crystallized as a single-phase compound in the hexagonal CaCu5 type structure. The substitution of Ce by La leads to increase the unit cell volume of the alloy. Hydrogen storage capacity has been investigated in the temperature and pressure range of 293 K ≤ T ≤ 323 K and 0.5 ≤ P ≤ 45 bar respectively using pressure-composition isotherm. The P-C isotherm curves show that the plateau pressure of the hydrogen absorption decreases and hydrogen storage capacity increases with increasing La content in the alloy. The enthalpy (∆H) and entropy (∆S) of dissolved hydrogen for all systems has been calculated using Van't Hoff plot. The variation of ∆H and ∆S with hydrogen content has also been studied which confirm the phase boundaries.