Metallic nanocrystals synthesized in solution: a brief review of crystal shape theory and crystallographic characterization

Abstract

This article reviews the main theoretical/computational techniques and the experimental characterization methodologies that are used in the quest to investigate the shape, size, composition, and crystallography of metallic nanoparticles. Two morphological regimes are described, one governed by equilibrium thermodynamics, and another in which the shape can be controlled kinetically: in each case, the focus is on key phenomenological effects, ignoring to a large extent the specifics of the materials. For the equilibrium crystal shape, the field has recently experienced developments beyond the basic Wulff construction. For the kinetically controlled case, we argue that models informed by experiments can lead to insights into the growth mechanisms, as well as into the resulting shapes and morphologies. Experimentally, the increasing resolution of characterization techniques can inform and validate the growth models. While ex situ characterization techniques have become de facto standards for investigations of nanoparticles, in situ techniques offer significant advances in spatial and temporal resolution and help establish a fundamental understanding of growth mechanisms.