Study on the hydrogen storage property of (TiZr0.1)(x)Cr1.7-yFeyMn0.3 (1.05 < x < 1.2, 0.2 < y < 0.6) alloys

Abstract

The hydrogen storage of (TiZr0.1)(x)Cr1.7-yFeyMn0.3 (1.05 < x < 1.2, 0.2 < y < 0.6) alloys, prepared by Ar plasma arc melting, were investigated by X-ray diffraction, pressure-composition-temperature (PCT). The results indicated that all (TiZr0.1)(x)Cr1.7-yFeyMn0.3 (1.05 <= x <= 1.2, 0.2 <= y <= 0.6) alloys were determined as C14-type Laves phase, the cell parameters a, c and unit cell volume of (TiZr0.1)(x)Cr1.1Fe0.6Mn0.3 (1.05 <= x <= 1.2) alloys increased with increasing the (TiZr) super-stoichiometry from 1.05 to 1.2, and the value of a/c almost unchanged. The hydrogen absorption and desorption plateau pressure decreased from 5.6, 4.4-2.6, 2.2 MPa with the increase of (TiZr) super-stoichiometry from 1.05 to 1.2 at 274 K respectively, and the hydrogen desorption plateau pressure decline was not obvious when the (TiZr) super-stoichiometry exceeded 1.15. The (TiZr0.1)(1.1)Cr1.1Fe0.6Mn0.3 alloy had the best comprehensive properties about the maximum and reversible hydrogen storage capacity was 1.79 and 1.45 wt% respectively. The cell parameters a, c and unit cell volume of (TiZr0.1)(1.1)Cr1.7-yFeyMn0.3(0.2 <= y <= 0.6) alloys increased as the ratio of Fe/Cr content decreased. The hydrogenation and dehydrogenation plateau pressure decreased from 4.5, 3.4-1.0, 0.9 MPa respectively and the maximum hydrogen storage capacity increased from 1.79 to 2.0 wt% as the Fe content reduced from 0.6 to 0.2 at 274 K. The maximum and the reversible hydrogen storage capacity were about 2.0 and 1.65 wt% as the ratio of Fe/Cr was 0.13 (ie, (TiZr0.1)(1.1)Cr1.5Fe0.2Mn0.3 alloy), its relative molar enthalpy of dissociation hydrogen was 24.30 kJ/mol H-2.