Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1600764 | Intermetallics | 2011 | 11 Pages |
The effect of Pd substitution on the crystal structure and hydrogenation properties of TiNi compound has been investigated. Ti(Ni,Pd) are pseudo-binary compounds. The unit-cell volumes of B2 (Austenite) and B19 (Martensite) structures linearly increase with Pd substitution in Ti1.04Ni0.96−xPdx samples. The hydrogenation properties of Pd-substituting Ti(Ni,Pd) compounds are not affected by the crystal structure of the parent compounds. For all samples, hydrogen absorption occurs without showing any clear plateau pressure in Pressure-Composition-Isotherm (PCI) curves. All hydrided samples crystallise in the tetragonal I 4/mmm space group. At 6 MPa of hydrogen pressure and T = 423 K, the hydrogenation capacity of Ti(Ni,Pd) compounds reaches 1.52 hydrogen atoms per formula unit (H/f.u.) for x = 0.1 and then gradually decreases with Pd content down to 0.93 H/f.u. for x = 0.5. Ti1.04Ni0.86Pd0.10 sample yields a discharge capacity of 148 mAh/g at C/5 regime when used as negative electrode in Ni-MH battery. The hydrogenation properties of Pd-substituting Ti(Ni,Pd) compounds are discussed in detail by comparison with previous studies on Zr substituting, (Ti,Zr)Ni compounds.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ti(Ni,Pd) compounds behave as pseudo-binary compounds. ► Their hydrogenation properties are not affected by the martensitic transformation. ► All Ti(Ni,Pd) hydrides crystallize in I4/mmm tetragonal symmetry. ► Hydrogenation capacity decreases with Pd content in Ti(Ni,Pd) compounds. ► Electronic effects probably dictate the hydrogenation properties of Ti(Ni,Pd) compounds