Anisotropic growth of multi-twinned goethite particles by oriented aggregation

Abstract

Goethite (α-FeOOH) nanostructures with tunable sizes and shapes were prepared by aging ferrihydrite nanoparticles in aqueous media without the assistance of organic additives. Novel anisotropic assemblies of α-FeOOH nanocrystallites were characterized by high-resolution TEM. In particular, various stages of twinning mediated by oriented aggregation were identified on α-FeOOH particles for the first time. Oriented aggregation not only leads to one-dimensional (1D) assembly of nanoparticles, but results in two-dimensional (2D) side-by-side organization of twinned nanorods. The rod-like 1D and 2D particles show pseudoperiodical multi-twinning nanostructures along the <112> direction. The results from the current study shed new light on oriented aggregation, which directs extended defect structures as building blocks for self-assembling unique and useful nanocrystals.