Size-dependent melting of spherical copper nanoparticles

TL;DR

This study investigates how the melting behavior of spherical copper nanoparticles embedded in silica varies with size, revealing a transition from gradual melting in smaller particles to abrupt melting in larger ones.

Contribution

It demonstrates size-dependent melting regimes in copper nanoparticles, identifying a critical size around 20 nm where the melting behavior changes.

Findings

Nanoparticles smaller than 20 nm melt gradually, indicating superheating.

Larger than 20 nm exhibit abrupt melting, similar to bulk copper.

Melting behavior transitions from continuous to first-order at ~20 nm.

Abstract

We report size-dependent melting of spherical copper nanoparticles embedded into silica matrix. Based on the temperature dependence of the surface plasmon resonance energy and its width we observe two distinct melting regimes. For particles smaller than 20 nm the absorption spectrum changes monotonically with the temperature, and this allows us to assume the gradual solid-liquid phase transition (melting) of the nanoparticles or existence of superheated solid nanoparticles. In contrast, for nanoparticles larger than 20 nm, we observe a jump-like increase of the bandwidth and non-monotonic dependence of surface plasmon energy at the temperatures below the bulk melting point. This indicates that the melting of large nanoparticles is a first-order phase transition similar to the melting of bulk copper.