X-ray diffraction and H-storage in ultra-small palladium particles
| Autor: | S. Kishore, Humberto R. Gutierrez, D. G. Narehood, J. A. Nelson, Peter C. Eklund, H. Goto, James H. Adair |
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| Rok vydání: | 2009 |
| Předmět: |
Phase transition
Phase boundary Hydrogen Renewable Energy Sustainability and the Environment Chemistry Hydride Analytical chemistry Energy Engineering and Power Technology Nanoparticle chemistry.chemical_element Condensed Matter Physics Crystallography Fuel Technology Phase (matter) X-ray crystallography Solid solution |
| Zdroj: | International Journal of Hydrogen Energy. 34:952-960 |
| ISSN: | 0360-3199 |
| DOI: | 10.1016/j.ijhydene.2008.10.080 |
| Popis: | In situ X-ray diffraction (XRD) and gravimetric hydrogen uptake measurements of d ∼ 2–3 nm spherical PdH x particles have been studied in the temperature and pressure range of 323 T P x , these highly crystalline PdH x nanoparticles also exhibit a complete transformation from the dilute α solid solution phase to the more concentrated β hydride phase. However, we observed that the character of the α–β phase transition in these nanoparticles is very different from that in the bulk. Indeed, the hydrogen uptake isotherm exhibits a noticeable positive slope in the α + β co-existence region. Furthermore, we also observed a noticeable narrowing of the α + β co-existence region ( δx ) in the nanoparticles. Also, a significant suppression of the critical temperature T c for the phase boundary was observed: T c (nano) ≈ 430 K while T c (bulk) ≈ 570 K. These results signal a significant change in the thermodynamic behavior of very small hydride nanoparticles that may be common to many other nano-scale metal hydride systems as well. |
| Databáze: | OpenAIRE |
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