Jump to main content
Jump to site search

Issue 8, 2014
Previous Article Next Article

Aggregation-induced growth and transformation of β-FeOOH nanorods to micron-sized α-Fe2O3 spindles

Author affiliations

Abstract

Intimate interconnection of crystal growth, (oriented) aggregation and phase transformation seem common in the formation of nano- and microcrystalline materials from solutions. Yet, the mechanistic linkages between the different processes have not been fully understood. In this work, we studied the hydrothermal growth of akaganeite (β-FeOOH) nanorods and their transformation to micron-sized hematite (α-Fe2O3) spindles using high-resolution cryogenic transmission electron microscopy (cryo-TEM). Only akaganeite particles and hematite spindles were detected in the samples. Further, cryo-electron 3D tomograms show that akaganeite nanorods were aggregated into loose three-dimensional networks with some embedded hematite spindles. Based on our cryo-TEM and additional X-ray diffraction, electron microscopy, and chemical data, we propose the following mechanism: first, formation of the early-stage hematite spindles is driven by phase stability change due to increase in size caused by oriented aggregation of akaganeite. Then, akaganeite particles continue to transform to hematite upon contact with and recrystallization onto hematite surfaces, making hematite grow with a constant aspect ratio and forming micron-sized nano-porous single-crystal spindles. Our growth model interprets experimental observations well and it resolves previous long-time debate over whether the hematite spindles are formed via classical Ostwald ripening or by oriented aggregation of hematite nanoparticles. Possibly, this aggregation-based concurrent growth and transformation model may also be applicable to crystal growth and phase transformation in other systems.

Graphical abstract: Aggregation-induced growth and transformation of β-FeOOH nanorods to micron-sized α-Fe2O3 spindles

Back to tab navigation

Publication details

The article was received on 31 May 2013, accepted on 21 Oct 2013 and first published on 22 Nov 2013


Article type: Paper
DOI: 10.1039/C3CE40983J
Citation: CrystEngComm, 2014,16, 1451-1458
  • Open access: Creative Commons BY license
  •   Request permissions

    Aggregation-induced growth and transformation of β-FeOOH nanorods to micron-sized α-Fe2O3 spindles

    C. Frandsen, B. A. Legg, L. R. Comolli, H. Zhang, B. Gilbert, E. Johnson and J. F. Banfield, CrystEngComm, 2014, 16, 1451
    DOI: 10.1039/C3CE40983J

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements