Modeling cohesive energy of nanosolid based on averaged coordination number
S. Morshedi*a , A. Yazdani band M. R. Rostamic
aDepartment of physics، of Islamic Azad university north Tehran .Iran
(Sabah_morshedi@yahoo.com)
bDepartment of physics ،university of Tarbiat modares. iran
While the cohesive energy of material is well known to be the energy needed to divided the material into isolated atoms, but in the Nano-Structure it is still could be a question whether;
(i) The increased surface energy should be equal to the cohesive energy of the material, which results from the surface area difference (SAD) between the total atoms and the material[ 1].
(ii) In the metallic nanostructure it is decreased with the decreasing of the size of the particle[2 ].
Since the surface-to-volume ratio is the effective parameter on the size and shape of the nano-structure the cohesive energy should be the functional of both the surface and interior atoms,(where it should depends of the strength and the angle of the chemical bond on which a large dangling bonds is exist).
Consequently the formation of the cohesive energy should be considered by functional of the, form factor, coordinate number and structural factor;
It is also suggested that the strength of the surface bond, due to the distribution of the bond-energy, degree of freedom, and as container, should be stronger than the interior bonds( ).
If the ratio of this energy is suppose to be a constant ,which is supposed to be equal[3] ,the ratio of cohesive energy of nano metallic system to the bulk could be fined as follow:
Where , are the number of nearest neishbour and the size of Nano Particle with is the critical size on which the atoms are located on the surface and is the form shape factor.and are the number of total،interior and surface atomsin the nanostructures.
Keywords: cohesive energy. coordination number. Nanostructure. . bond-energy.
References:
[1]W.H. Qi, M.P. Wang, Size and shape dependent melting temperature of metallic
nanoparticles, Mater. Chem. Phys. 2004, 88: 280.
[2]K. K. Nanda, S. N. Sahu, and S. N. Behera, 2002. Liquid-drop model for the sizedependent
melting of low-dimensional systems, Phys. Rev. A, 66: 013208.
[3]M. Attarian Shandiz, A. Safaei, S. Sanjabi, Z.H. Barber, "Modeling of the Cohesive Energy and Melting Temperature of Nanoparticles by Calculation of Average Coordination
Number",SolidState Communications 145 (2008) 432
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