Can nano-particle stand above the melting temperature of its fixed surface partner?

TL;DR

This paper investigates how boundary conditions influence the melting temperature of nano-particles by analyzing phonon contributions and phase shifts, revealing that boundary effects can raise or lower melting points and establish an upper temperature limit.

Contribution

It introduces a size-dependent melting temperature model based on phonon phase shifts caused by boundary scattering, highlighting the boundary condition's role in melting behavior.

Findings

Boundary conditions can increase or decrease nano-particle melting temperatures.

An upper melting temperature bound exists under fixed boundary conditions.

The model accounts for complex phonon integration volumes in nano-particles.

Abstract

The phonon thermal contribution to the melting temperature of nano-particles is inspected. Unlike in periodic boundary condition, under a general boundary condition the integration volume of low energy phonon for a nano-particle is more complex. We estimate the size-dependent melting temperature through the phase shift of the low energy phonon mode acquired by its scattering on boundary surface. A nano-particle can have either a rising or a decreasing melting temperature due to the boundary condition effect, and we found that an upper melting temperature bound exists for a nano-particle in various environments. Moreover, the melting temperature under a fixed boundary condition sets this upper bound.