Introduction

Abstract

The transmission electron microscopy image in Fig.1.1a shows well-dispersed magnetite particles with a dimension below 10nm, i.e., nanoparticles. The black arrows in this figure indicate the presence of equiaxial (almost spherical) particles and well-faceted (triangular-shaped) nanoparticles. A high-resolution transmission electron microscopy analysis (see Fig.1.1b, c) reveals that each particle is formed by a single crystalline domain; i.e., each particle is a single crystal and both particles have the same crystalline structure despite a different shape.