Definition of Interface Parameter and Its Application on Estimating the Thermal Stability of Metallic Nanoparticles

To describe the effect of the interface structure on the thermal stability of nanoparticles (NPs) that are embedded in a matrix, an interface parameter ψ is defined by considering both the interface energy γss and the interface stress fss. As ψ is introduced into a size-dependent melting model, the interface and size effects on the melting temperature Tm(ψ,D) is found. Results show that fss predominates the elevation and depression of Tm(ψ,D) for coherent and incoherent interfaces, while γss is only a secondary effect. Furthermore, Tm(ψ,D) decreases following the increase of ψ. Namely, ψ < 0 for coherent interfaces, ψ = 0 for bulk, 0 < ψ < 1 for incoherent interfaces, and 1 < ψ for the core–shell structure where the low melting point element is located at the core. The success in the prediction of Tm(D) for metallic NPs confirms the validity of parameter ψ.