In-Situ Powder Diffraction Measurements of Hydrogen Storage in Ti-Zr-Ni Quasicrystals. S.T. Misture, Alfred University, Alfred, NY 14802; R.M. Stroud, and K.F. Kelton, Washington University, St. Louis, MO 63130.

High temperature x-ray powder diffraction was used to determine the hydrogen cycling behavior of a novel material, Ti₄₅Zr₃₈Ni₁₇-H quasicrystal, and demonstrate its potential for application in hydrogen storage systems. Of paramount importance for hydrogen storage is the thermodynamic stability of the host alloy. The first in-situ x-ray diffraction measurements of quasicrystal-crystal and crystal-crystal transformations in three TiZrNi alloys will be presented. In addition, the first evidence of the thermodynamic stability of Ti₄₅Zr₃₈Ni₁₇-H was determined in-situ.

Calibration of hydrogen content to quasilattice parameter allowed the application of powder diffraction to monitor desorption of hydrogen from the alloy under inert gas, as well as hydrogen resorption under 1 atmosphere of H₂. The maximum change in hydrogen content observed was from 61 at.% at room temperature to 2.5 at.% at 620(C. Desorption of hydrogen begins at about 350(C and continues up to the quasicrystal decomposition temperature of 665(C. Hydrogen loading in the quasicrystal to > 20 at.% occurs at temperatures up to ~350(C when exposed to 1 atm. H₂.