Vibrational Properties of Nanoscale Materials: From Nanoparticles to Nanocrystalline Materials

Abstract

The vibrational density of states (VDOS) of nanoclusters and nanocrystalline materials are derived from molecular-dynamics simulations using empirical tight-binding potentials. The results show that the VDOS inside nanoclusters can be understood as that of the corresponding bulk system compressed by the capillary pressure. At the surface of the nanoparticles the VDOS exhibits a strong enhancement at low energies and shows structures similar to that found near flat crystalline surfaces. For the nanocrystalline materials an increased VDOS is found at high and low phonon energies, in agreement with experimental findings. The individual VDOS contributions from the grain centers, grain boundaries, and internal surfaces show that, in the nanocrystalline materials, the VDOS enhancements are mainly caused by the grain-boundary contributions and that surface atoms play only a minor role. Although capillary pressures are also present inside the grains of nanocrystalline materials, their effect on the VDOS is different than in the cluster case which is probably due to the inter-grain coupling of the modes via the grain-boundaries.

10 pages, 7 figures, accepted for publication in Phys. Rev. B

References in corpus (2)

• Atomic-scale modeling of the deformation of nanocrystalline metals
• Stacking-fault energies for Ag, Cu, and Ni from empirical tight-binding potentials

Cited by in corpus (6)

• Vibrational density of states of silicon nanoparticles
• Acoustic modes in metallic nanoparticles: atomistic versus elasticity modeling
• Effects of morphology on phonons of nanoscopic silver grains
• Vibrational properties and stability of FePt nanoalloys
• A hybrid algorithm for parallel molecular dynamics simulations
• Vibrations of closed-shell Lennard-Jones icosahedral and cuboctahedral clusters and their effect on the cluster ground state energy