Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model

TL;DR

This study predicts a comprehensive phase diagram for binary nanoparticle superlattices using Lennard-Jones potentials, revealing universal features and structural motifs that align with experimental phases and packing models.

Contribution

It introduces a universal phase diagram for binary nanoparticle superlattices based on Lennard-Jones interactions, highlighting structural motifs and metastable phases.

Findings

Identified 53 equilibrium phases in the phase diagram.

Demonstrated universality of phase stability across potential details.

Linked lattice motifs to experimental superlattices and packing models.

Abstract

A first principle prediction of the binary nanoparticle phase diagram assembled by solvent evaporation has eluded theoretical approaches. In this paper, we show that a binary system interacting through Lennard-Jones (LJ) potential contains all experimental phases in which nanoparticles are effectively described as quasi hard spheres. We report a phase diagram consisting of 53 equilibrium phases, whose stability is quite insensitive to the microscopic details of the potentials, thus giving rise to some type of universality. Furthermore, we show that binary lattices may be understood as consisting of certain particle clusters, i.e. motifs, which provide a generalization of the four conventional Frank-Kasper polyhedral units. Our results show that meta-stable phases share the very same motifs as equilibrium phases. We discuss the connection with packing models, phase diagrams with repulsive potentials and the prediction of likely experimental superlattices.