Size effect on Debye temperature of metal crystals

Abstract

Understanding the physical origin of materials exhibiting different properties at the mesoscale is of great significance for the design and fabrication of multifunctional quantum devices. In this work, we proposed a simple model without any adjustable parameters to describe the size (D) dependence of Debye temperature Θ_D(D) of metallic nanocrystals. Θ_D(D) drops with the decrease of D, which is verified by relevant experimental and simulation results. In addition, we found that the difference in the size dependence of Θ_D(D) of different metal elements is determined by the ratio of the solid/liquid interface energy γ_sl and surface stress f, and the smaller the D of the nanocrystals, the greater the influence of γ_sl/f on Θ_D(D)/Θ_D.