J. Moscovici et al., Unexpected Fe local order in iron oxide-coated nanocrystalline magnesium oxides with exceptional reactivities against environmental toxins, J SYNCHROTR, 8, 2001, pp. 925-927
Mg oxide nanoparticles are very reactive materials used to mitigate atmosph
eric pollution and to sequester polluting molecules. Using Fe K-edge XAFS,
we have studied the structure of iron oxide-coated MgO nanoparticles before
and after reaction with CCl4. Before reaction, the local structure around
Fe is totally different from that in iron oxide coatings on SrO and CaO nan
oparticles, although these coated materials were prepared in the same way.
In SrO and CaO, the iron oxide coating has been shown to be well separated
from the bulk of the nanoparticle, whereas in MgO, Fe was found to mix with
MgO. After reaction with CCl4, Fe-Cl bonds can be detected when the coated
nanoparticle is saturated. Such Fe-Cl EXAFS signals have not been observed
in previously studied nanoparticles.