| Popis: |
The interface energy is general factor, which has determined the critical size and equilibrium shape of nanoparticles, velocity of its growth and stability. The electron-statistical method, based on the Thomas-Fermi theory taking into account its current state, allows one to calculate the interfacial energy of metallic objects of different dimensions at the boundary with various media. Based on this method, we have developed a variant for calculating the interfacial energy of the system « low-dimensional metallic phase - polar dielectric film». The polyatomic alcohols (diols), used, for example, as non-aqueous media for the synthesis of metal nanoparticles, were chosen as the external medium. Also we have chosen cobalt nanocrystals as a low-dimensional metallic phase. Expressions are obtained for the external and internal contributions to the interfacial energy of the system, including the polarization correction, due to the presence of a dielectric fluid in the external region of the system. The effect of a limited dielectric fluid layer on the Gibbs boundary coordinate is analyzed. The presence of a dielectric leads to a shift of the Gibbs boundary to the external region of the system, that is, the so-called effect of «pulling the tail» of the electron density is observed. It is shown that with increasing dielectric constant, the magnitude of the polarization contribution increases rapidly in magnitude. The interface energy of a cobalt nanocrystal at the interface with polar polyatomic alcohols is calculated. The interfacial energy of the faces of cobalt nanocrystals decreases nonlinearly with an increase in the linear dimensions of the metal phase. It is shown that the dielectric coating changes the character of the dimensional and orientational dependence in comparison with the interfacial energy of macrocrystals and thin films at the interface with vacuum. With a constant size of the metal phase and an increase in the thickness of the dielectric coating, the interface energy of faces and anisotropy increase. It has been established that 1,2-ethanediol is the most effective surfactant for cobalt particles of the polyatomic alcohols considered in this paper. The dependencies obtained in this work are consistent with the literature data for the thin films of alkaline metals and other system. |
