Pressure–composition–temperature curves and structure stability induced by hydrogen in TiZrNi quasicrystals

Abstract

To evaluate the potential applications of Ti-based quasicrystals as hydrogen storage materials, metastable Ti_{53– x} Zr₂₇Ni₂₀Pd _x (x = 0, 2, 4, 6) quasicrystals were prepared by a rapid quenching method and equilibrium vapor pressures for hydrogen were measured. Pressure–composition–temperature curves measured in Pd-added TiZrNi quasicrystals revealed a significantly increased equilibrium vapor pressure for hydrogen with increasing Pd concentration, while hydrogen loading capacity decreased. After hydrogen absorption, no hydride phase was found for samples made with less than x = 4. The main peaks shifted to the lower angle of 2θ in X-ray diffraction patterns, demonstrating that the quasi-lattice constants increased from 5.13 to 5.38 Å after hydrogenation. The quasi-lattice constants linearly expanded with increasing absorption amount of hydrogen. Interestingly, analyzing the full width at half maximum values of the main peaks in the X-ray diffraction patterns showed that the coherence lengths of the quasicrystals significantly increased from 120 to 240 Å after hydrogenation, presumably due to kinetic rather than thermal factors.

Keywords:

• quasicrystals
• TiZrNiPd
• hydrogen storage
• P–c–T curves

Acknowledgements

This work was supported by the Korea Research Foundation Grant (KRF-2010-0023492) funded by the Korea Government (MOEHRD), Research Fund of HYU-2010-T, and by the Nuclear R&D program through the National Research Foundation, International Research & Development Program funded by the Ministry of Education, Science and Technology (MEST) of Korea (Grant No. K20901000006-09E0100-00610) and the Seoul R&D Program (10919).