An experimental investigation on the poor hydrogen sorption properties of nano-structured LaNi5 prepared by ball-milling
✍ Scribed by B. Joseph; B. Schiavo; G. D’Alì Staiti; B.R. Sekhar
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 608 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0360-3199
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✦ Synopsis
Nano-structured LaNi 5 hydrogen storage materials prepared by ball-milling is analysed using differential scanning calorimetry (DSC) and x-ray photoelectron spectroscopy (XPS).
DSC results indicate a partial elimination of defects at 500 C in a more efficient way for the short-time ball-milled powders compared to the long-time ball-milled ones. XPS results
show almost no change in the core-level electronic structure for La and Ni of LaNi 5 in the bulk and the nano-structured forms, but gives an indication that the self-restoring mechanism of the active surface observed in the bulk sample (Siegmann et al. Phys. Rev. Lett. 40, 972) may not be occurring in the nano-powders. Results from the X-ray diffraction and the local structural studies together with the above observations suggest that the reduced unit-cell volume and the enhanced atomic disorder in the nano-structured LaNi 5 cause a larger energy barrier for the hydrogen sorption reactions of the long-time ballmilled samples.