Hyunjeong Kim1, Kouji Sakaki1, Kohta Asano1, Kazutaka Ikeda2, Toshiya Otomo2, Akihiko Machida3, Tetsu Watanuki3 and Yumiko Nakamura1
1Hydrogen Energy Technology Group, Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8565
The effect of a quenching rate on the hydrogen storage properties of V0.79Ti0.2Zr0.01 was investigated. Two V0.79Ti0.2Zr0.01 samples with different quenching rates were prepared; one was quenched from 1673 K to the ice-water temperature in less than 1 s (V0.79Ti0.2Zr0.01-FQ) and the other was quenched more slowly (V0.79Ti0.2Zr0.01-SQ). Both samples are single phase and no notable difference in their average structure was found. Pressure-composition isotherm curves representing transition between monohydride and dihydride phases at 410 K show that V0.79Ti0.2Zr0.01-FQ absorbs hydrogen at much higher pressure than V0.79Ti0.2Zr0.01-SQ. In addition, V0.79Ti0.2Zr0.01-FQ has a more slanting absorption plateau. During 15 hydrogen absorption and desorption cycles, gradual reduction in hydrogen absorption plateau pressure was observed only in V0.79Ti0.2Zr0.01-FQ. Our preliminary local structural study using the atomic pair distribution function analysis show that their structural correlations start to deviate around 5.5 nm. [doi:10.2320/jinstmet.JC201405]
hydrogen storage materials, vanadium-based bcc alloys, quenching effect
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