Nucleation and growth of magnetite from solution

• Published in: Nature materials 2013-04, Vol.12 (4), p.310-314
• Main Authors: Baumgartner, Jens, Dey, Archan, Bomans, Paul H. H., Le Coadou, Cécile, Fratzl, Peter, Sommerdijk, Nico A. J. M., Faivre, Damien
• Format: Article
• Language: English
• Subjects: 639/301/1034; 639/301/357; 639/301/930/1032; Agglomeration; Biomaterials; Condensed Matter Physics; Crystal structure; Ferric Compounds - chemistry; Ferrosoferric Oxide - chemistry; Iron oxides; letter; Liquid Crystals - chemistry; Materials Science; Microscopy, Electron, Transmission; Minerals; Nanocomposites; Nanomaterials; Nanostructure; Nanotechnology; Nucleation; Optical and Electronic Materials; Particle physics; Precursors; Solutions; Thermodynamics; Transmission electron microscopy
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat3558

The crystallization of many minerals from solution has been shown to involve disordered precursors that agglomerate into an amorphous intermediate phase, a pathway that seems to contradict classical nucleation theory. It is now found that the crystallization of magnetite—a magnetic iron oxide with many bio- and nanotechnological applications—occurs classically from the accretion of precursors in the absence of amorphous intermediates. The formation of crystalline materials from solution is usually described by the nucleation and growth theory, where atoms or molecules are assumed to assemble directly from solution 1 . For numerous systems, the formation of the thermodynamically stable crystalline phase is additionally preceded by metastable intermediates 2 . More complex pathways have recently been proposed, such as aggregational processes of nanoparticle precursors or pre-nucleation clusters, which seem to contradict the classical theory 3 , 4 , 5 , 6 . Here we show by cryogenic transmission electron microscopy that the nucleation and growth of magnetite—a magnetic iron oxide with numerous bio- and nanotechnological applications 7 —proceed through rapid agglomeration of nanometric primary particles and that in contrast to the nucleation of other minerals 5 , no intermediate amorphous bulk precursor phase is involved. We also demonstrate that these observations can be described within the framework of classical nucleation theory.