Joanna Czub

Metastable amorphous or quasicrystalline materials are very intriguing regarding hydrogen storage by gaseous or electrochemical means. In this contribution, we report the results of studies on the formation of the Ti45Zr38Ni17 icosahedral ribbons prepared by the melt spinning method. It is evidenced that quasicrystalline specimens of high quality can be obtained for a moderate spinning speed of 30 m s-1. Measurements of the hydrogen storage capacity for the gaseous phase yielded the maximum hydrogen concentration for the powdered ribbons equal to 2.60 wt.% at 20°C. The article examines the influence of temperature on hydrogen storage in quasicrystals.

The amorphous materials of the Ti₄₅Zr₃₈Ni₁₇ composition synthesized by mechanical alloying are widely recognized for their ability to store hydrogen with gravimetric densities above 2 wt.%. It is also known that those alloys can form a quasicrystalline state after thermal treatment and their structural and hydrogen sorption properties can be altered by doping with various elements. Therefore, in this paper, the results of the studies on the Ti₄₅Zr₃₈Ni₁₇ system with yttrium substituted for titanium and zirconium are presented. We demonstrate that these alloys are able to absorb hydrogen with a concentration of up to 2.7 wt.% while retaining their amorphous structure and they transform into the unique glassy-quasicrystal phase upon annealing. Furthermore, we demonstrate that the in-situ hydrogenation of those new materials is an effortless procedure in which the decomposition of the alloy can be avoided. Moreover, we prove that, in that process, hydrogen does not bind to any specific component of the alloy, which would otherwise cause the formation of simple hydrides or nanoclusters.

The mechanically alloyed amorphous alloys of the Ti₄₅Zr₃₈Ni₁₇ composition are known for their ability to form a quasicrystalline state after thermal treatment. It is also known that the amorphous and quasicrystal alloys belonging to the Ti₄₅Zr₃₈Ni₁₇ family are able to store hydrogen and yield gravimetric densities above 2 wt.%. In this contribution, we report the results of research on the Ti₄₅Zr₃₈Ni₁₇ system with vanadium doped instead of titanium. We found that the amorphous samples with moderate doping (x < 20) show the ability to absorb hydrogen while maintaining the amorphous state and they transform into the novel glassy-quasicrystal phase during annealing. Those materials with higher vanadium concentrations do not form entirely amorphous structures. However, they still can absorb hydrogen easily. It was also confirmed that the in situ hydrogenation of the amorphous alloys is a straightforward process without decomposition of the alloy. In this process, hydrogen does not attach to any particular constituent of the alloy, which would lead to the formation of simple hydrides or nanoclusters. Therefore, we were able to confirm the fully amorphous nature of the deuterides/hydrides of the Ti_45−xV_xZr₃₈Ni₁₇ with moderate V doping.

The alloys based on Ti-Zr are considered an excellent candidate for hydrogen storage applications. In this communication, we report the results of Fe substitution for Ni in the well-known Ti₄₅Zr₃₈Ni₁₇ compound. The parent and related compounds can be obtained as amorphous powders, transforming into the quasicrystalline phase (i-phase) after annealing. The amorphous Ti₄₅Zr₃₈Fe₁₇ phase is transformed into the icosahedral quasicrystalline state, and it is a quasi-continuous process. The i-phase is well-developed close to 500 °C. At higher temperatures, the quasicrystal structure transforms into the other phase: the w-phase (an approximant to the crystalline phase) and another crystal phase with a small addition of the FeZr₃ and the Fe₂(ZrTi)₃. The amorphous Ti₄₅Zr₃₈Fe₁₇ phases can be hydrogenated while maintaining the amorphous nature, which constitutes another very fascinating research field for our group. The investigated alloy shows a good capacity for gaseous H₂ at level 2.54 wt.% at elevated temperatures. The ferromagnetic signal of the amorphous TiZrFe comes from magnetic nanocrystallites in the amorphous matrix. After heating, the magnetic signal significantly decreases due to the lack of long-range magnetic ordering in the i-phase of the Ti₄₅Zr₃₈Fe₁₇ alloy.