| AVS 54th International Symposium | |
| Surface Science | Thursday Sessions |
| Session SS-ThP |
| Session: | Surface Science Poster Session |
| Presenter: | H.H. Farrell, Idaho National Laboratory |
| Authors: | H.H. Farrell, Idaho National Laboratory C.D. Van Siclen, Idaho National Laboratory D.M. Ginosar, Idaho National Laboratory L.M. Petkovic, Idaho National Laboratory R.D. Parra, DePaul University |
| Correspondent: | Click to Email |
The nature of the bonding at surfaces has a profound effect on their properties. Current models for the cohesive energy of nanoparticles generally predict a linear dependence on the inverse particle diameter, 1/r, for low aspect-ratio (spherical) clusters.@super1-4@ Although this is generally true for metals, we have recently found that for the Group IV semiconductors, C, Si and Ge, this linear dependence does not hold.@super5. Instead, using first principles, density functional theory calculations to calculate the binding energy of these materials, we find a roughly quadratic dependence on the inverse of the particle size. Similar results have also been obtained for the metallic Group IV elements Sn and Pb and for Mg, another "poor" metal.@super5@ This result is in direct contradiction to current assumptions. Further, as a consequence of this quadratic behavior, the melting point of these materials will not be linear in 1/r, but will experience less suppression than experienced by metal nanoparticles with comparable bulk binding energies. Similarly, the vapor pressure of semiconductor nanoparticles will rise more slowly with decreasing size than would be expected. This non-linearity also affects sintering or Ostwald ripening behavior of these nanoparticles as well as other physical properties that depend on the nanoparticle binding energy. The reason for this variation in size dependence involves the covalent nature of the bonding in semiconductors, and even in the "poor" metals. New work on other materials, including compound semiconductors and oxides will also be presented.
1See, for example, S. C. Vanithakumari, and K. K. Nanda, J. Phys. Chem. B 110, 1033 (2006), and references therein.
2See, for example, W. H. Qi, M. P. Wang, M. Zhou, and W. Y. Hu, J. Phys. D: Appl. Phys. 38, 1429 (2005), and references therein.
3See, for example, Chang Q. Sun, H. L. Bai, S. Li, B. K. Tay, C. Li, T. P. Chen, and E. Y. Jiang, J. Phys. Chem. B 108, 2162 (2004), and references therein.
4See, for example, M. Wautelet, J. P. Dauchot, and M. Hecq, J. Phys.: Condens. Matter 15, 3651 (2003), and references therein.
5H. H. Farrell and C. D. Van Siclen, accepted for publication in J.Vac. Sci. Technol. B.