Structure and properties of iron oxide clusters: From Fe6 to Fe6O20 and from Fe7 to Fe7O24 |
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| Authors: | Gennady L Gutsev Kalayu G Belay Lavrenty G Gutsev Bala R Ramachandran |
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| Affiliation: | 1. Department of Physics, Florida A&M University, Tallahassee, Florida;2. Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida;3. College of Engineering & Science, Louisiana Tech University, Ruston, Louisiana |
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| Abstract: | Geometrical and electronic structures of the neutral and singly negatively charged Fe6On and Fe7Om clusters in the range of 1 ≤ n ≤ 20 and 1 ≤ m ≤ 24, respectively, are computed using density functional theory with the generalized gradient approximation. The largest clusters in the two series, Fe6O20 and Fe7O24, can be described as Fe(FeO4)5 and Fe(FeO4)6 or alternatively as FeO5](FeO3)5 and FeO6](FeO3)6, respectively. The Fe6O20 and Fe7O24 clusters possess adiabatic electron affinities (EAad) of 5.64 eV and 5.80 eV and can be attributed to the class of hyperhalogens since FeO4 is an unique closed‐shell superhalogen with the EAad of 3.9 eV. The spin character of the lowest total energy states in both series changes from ferromagnetic to ferrimagnetic or antiferromagnetic when the first Fe? O? Fe bridge is formed. Oxidation decreases substantially the polarizability per atom of the initial bare clusters; namely, from 5.98 Å3 of Fe6 to 2.47 Å3 of Fe6O20 and from 5.67 Å3 of Fe7 to 2.38 Å3 of Fe7O24. The results of our computations pertaining to the binding energies of O, Fe, O2, and FeO in the Fe7Om series provide an explanation for the experimentally observed abundance of the iron oxide nanoparticles with stoichiometric compositions. © 2016 Wiley Periodicals, Inc. |
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| Keywords: | iron oxide cluster superhalogen polarizability electron affinity antiferromagnetic state |
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