Measurements of the hydrogen absorption pressure composition isotherms in Ti/Zr-based quasicrystals

摘要

The first hydrogen abosrption pressure-composition isotherms (p-c-T were measrued in quasicrystalline ti_45Zr_38Ni_17.No evidence for a pressure plateau was found,indicating a distribution of energies for the hydrogent in interstitial sites.Fits to the p-c-T data confirmed this,givifng energy peaks at -0.19 eV with a full width at half maximum (half-width) of 0.06 eV,and at -0.09 eV with a half-width of 0.08 ev .This is in ocntrast with the broad site energy distribution that is characteristic of a metallic glass.In agreement,fits to data taken from amorphous Ti_45Zr_27Ni_20Si_8 gave a single broad energy distribution at -0.10 ev with a half-width of 0.35 eV.Based on the weighted averages of the site energies for the pure components,the energies assigned to the tetratedral sites in the Ti_44Zr_40Ni_16 1/1 approximant phase are in qualitative agreement with the measured data for the quasicrystal,supporting a local structural similarity between these two phases.Almost all of the absorbed hydrogen can be ddesorbed at 650 deg C in one hour by pumping,without transforming the quasicrystal phase and without powdering the rapidly-quenched samples.