Iron nanoparticle formation in a metal-organic matrix: from ripening to gluttony

TL;DR

This paper presents a simple vacuum heating method to produce well-defined iron nanoparticles within a carbon matrix, revealing distinct nucleation, ripening, and a unique 'gluttony' growth phase observed via in-situ TEM.

Contribution

It introduces a novel fabrication process for metal nanoparticles embedded in a carbon matrix and characterizes their formation dynamics, including a new 'gluttony' growth phase.

Findings

Iron nanoparticles form at 500°C with narrow size distribution

Particles undergo ripening and a 'gluttony' growth phase

In-situ TEM reveals detailed formation kinetics

Abstract

A simple method for the fabrication of metal nanoparticles is introduced. Heating metal-organic crystals in vacuum results in the formation of well defined metal particles embedded in a carbon matrix. The method is demonstrated for iron-phthalocyanine. At 500C homogeneously distributed iron nanoparticles with a reasonably narrow size distribution form by nucleation and ripening. After this initial phase the formation kinetics changes drastically. The particles move in the matrix to incorporate material. The "gluttony" phase shows astonishing similarities with the search for nutrition of living micro-organisms. Particle formation, ripening and gluttony are followed in-situ by transmission electron microscopy.