Atomistic Mechanisms for the Nucleation of Aluminium Oxide Nanoparticles

TL;DR

This paper develops a microscopic, first-principles model to predict aluminium oxide nanoparticle nucleation, addressing limitations of classical theories by considering atomistic structures and thermodynamics.

Contribution

It introduces a novel atomistic approach based on first-principles calculations to accurately model alumina cluster formation and nucleation processes.

Findings

Successfully reproduces experimental spectroscopy data

Provides detailed thermodynamic data for AlxOy clusters

Proposes a new scenario for alumina seed formation

Abstract

A predictive model for nanoparticle nucleation has not yet been successfully achieved. Classical nucleation theory fails because the atomistic nature of the seed has to be considered since geometrical structure as well as stoichiometry do not always match the bulk values. We present a fully microscopic approach based on a first-principle study of aluminium oxide clusters. We have calculated stable structures of AlxOy} and their associated thermodynamic properties. From these data, the chemical composition of a gas composed of aluminium and oxygen atoms can be calculated as a function of temperature, pressure, and aluminium to oxygen ratio. We demonstrate the accuracy of this approach in reproducing experimental results obtained with time resolved spectroscopy of a laser induced plasma from an Al2O3} target. We thus extended the calculation to lower temperatures, i.e. longer time scales, to propose a scenario of composition gas evolution leading to the first alumina seeds.