Abstract
Ferrite spinels, especially magnetite (Fe3O4), can be formed either by geological, biological or chemical processes leading to chemically similar phases that show different physical characteristics. We compare, for the first time, magnetite produced by these three different methods using X-ray magnetic circular dichroism (XMCD), a synchrotron radiation based technique able to determine the site occupancy of Fe cations in the ferrite spinels. Extracellular nanoscale magnetite produced by different Fe(III)- reducing bacteria was shown to have different degrees of stoichiometry depending on the bacteria and the method of formation, but all were oxygen deficient due to formation under anoxic conditions. Intracellular nano-magnetite synthesized in the magnetosomes of magnetotactic bacteria was found to have a Fe cation site occupancy ratio most similar to stoichiometric magnetite, possibly due to the tight physiological controls exerted by the magnetosome membrane. Chemically-synthesised nano-magnetite and bulk magnetite produced as a result of geological processes were both found to be cation deficient with a composition between magnetite and maghemite (oxidised magnetite). © 2007 E. Schweizerbart'sche Verlagsbuchhandlung.
Original language | English |
---|---|
Pages (from-to) | 707-716 |
Number of pages | 9 |
Journal | European Journal of Mineralogy |
Volume | 19 |
Issue number | 5 |
DOIs | |
Publication status | Published - Sept 2007 |
Keywords
- Biogenic magnetite
- Biominer-alogy
- Fe(III) reduction
- Geobacter
- Metal reduction
- Nanoparticles
- X-ray magnetic circular dichroism
- XMCD
Research Beacons, Institutes and Platforms
- Dalton Nuclear Institute