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Simple Synthesis of Versatile Akaganéite-Silica Core−Shell Rods

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Original languageEnglish
Pages (from-to)3449-3457
Number of pages9
JournalChemistry of Materials
Volume24
Issue number17
DOIs
Publication statusPublished - 11 Sep 2012

Abstract

We present a simple method for preparing large quantities of micrometer-sized core-shell silica rods, via needle-like akaganéite (β-FeOOH) template particles. The preparation of the akaganéite needles by aging ferric chloride solutions at elevated temperature is explored in order to find improved conditions for the formation of well-dispersed high-aspect-ratio needles. The influence of reaction conditions on irreversible bundling of the needles, yield, and the particle size distribution are reported and discussed. Subsequent coating of the template particles with silica leads to core-shell rods with an aspect ratio (A = L/D) that decreases with shell thickness. This facilitates control over the final aspect ratio and is accompanied by a decrease in the polydispersity. The composition of these core-shell particles offers various possibilities in terms of modifying the particle properties, which we demonstrate by preparing fluorescent particles and hollow silica rods while outlining other interesting options. We also include some optical microscopy images illustrating particle behavior and ordering under gravity, in a homogeneous magnetic field and at the interfaces of phase-separated binary liquids.

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