Surface energy and pressure of diamond and silicon nanocrystals |
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Authors: | M N Magomedov |
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Institution: | (1) State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China;(2) National Renewable Energy Laboratory, Golden, CO 80401, USA |
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Abstract: | Based on the pair potential of interatomic interaction, we study the dependence of various properties of diamond and silicon
nanocrystals with a free surface on size, surface shape, and temperature. A model nanocrystal has the form of a parallelepiped
faceted by {100} planes with a square base. The number of atoms N in the nanocrystals is varied from 5 to infinity. The Debye temperature, Gruneisen parameter, specific surface energy, isochoric
derivative of specific surface energy with respect to temperature, and surface pressure are calculated as a function of the
size and shape of diamond and silicon nanocrystals at temperatures ranging from 20 K to the melting point. The surface pressure
P
sf(N) ∼ N
−1/3 is much lower than the pressure calculated by the Laplace formula for similar nanocrystals for given values of density, temperature,
and number of atoms. As the temperature increases from 20 K to the melting point, the isotherm P
sf(N) lowers and changes the shape of the dependence on N; at high temperatures, it goes to the region of extension of small nanocrystals of diamond and silicon. |
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Keywords: | |
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