Hydrogen storage in Ti-Zr and Ti-Hf-based quasicrystals

The depletion of the world's petroleum reserves and the increased environmental impact of conventional combustion-engine-powered automobiles are leading to renewed interest in hydrogen storage materials. In the mid 1990s, Ti/Zr/Hf-based quasicrystals were demonstrated to store more hydrogen than competing crystal intermetallic phases. Unfortunately, recovery of the hydrogen required temperatures in excess of 400 degrees C, severely limiting the technological application of these materials. Here, the Ti/Zr-Hf-based quasicrystals and crystal approximants are reviewed and their hydrogenation properties are discussed. We also report the discovery of a relatively. at pressure plateau for hydrogenated TiZrNi quasicrystals at modest pressures (100-200 psi) that extends to hydrogen concentrations in excess of 4 wt.%. Approximately 2 wt.% of the hydrogen is easily recovered by heating at temperatures as low as 200 degrees C.