Hydrogenation properties of Pd-coated Zr-based Laves phase compounds

Pd thin film is deposited by radio frequency magnetron sputtering on ZrV₂ and Zr_0.9Ti_0.1V₂ substrates to investigate the effects of Pd coating on the hydrogenation properties of Zr-based Laves compounds. The growth characteristics and microstructure of Pd membrane are examined by XRD and SEM. The results indicate that the deposited Pd layer grows with the (111) preferred orientation. The results of hydrogenation property tests of the Zr-based alloys with Pd film show that Pd coating preserves no notable deterioration on the hydrogen absorption capabilities of the Zr-based alloys, while it leads to obvious reductions in the hydriding rates. Hydriding reaction rate of the rapid absorbing stage (k _α1) decreases by ∼37% for ZrV₂, and the reduction is about ∼42% for Zr_0.9Ti_0.1V₂. The average absolute values of enthalpy are 138 kJ mol^-1 and 137 kJ mol^-1 for the Pd coated ZrV₂ and Zr_0.9Ti _0.1V₂, respectively. The average absolute value of entropy is 105 J mol^-1 K^-1 for the former and 102 J mol ^-1 K^-1 for the latter.