title: Ordered mesoporous Fe2O3 with crystalline walls.
abstract: Alpha-Fe(2)O(3) has been synthesized with an ordered mesoporous structure and crystalline walls that exhibit a near-single crystal-like order. The unique magnetic behavior of the material, distinct from bulk nanoparticles of alpha-Fe(2)O(3) or mesoporous Fe(2)O(3) with disordered walls, has been established. Magnetic susceptibility, Mössbauer, and neutron diffraction data show that the material possesses the same long-range magnetic order as bulk alpha-Fe(2)O(3), despite the wall thickness being less than the 8 nm limit below which magnetic ordering breaks down in nanoparticulate alpha-Fe(2)O(3), yet the Morin transition of bulk alpha-Fe(2)O(3) is absent. It is also shown by TEM, PXRD, and EXAFS that alpha-Fe(2)O(3) with the same ordered mesoporous structure but disordered walls contains small crystalline domains. Mössbauer and magnetic susceptibility data demonstrate that this material exhibits no long-range magnetic order but superparamagnetic behavior.
authors.affiliation: School of Chemistry and EaStChem, University of St. Andrews, UK.
authors.forename: Feng
authors.initials: F
authors.lastname: Jiao
authors.forename: Andrew
authors.initials: A
authors.lastname: Harrison
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Jumas
authors.forename: Alan V
authors.initials: AV
authors.lastname: Chadwick
authors.forename: Winfried
authors.initials: W
authors.lastname: Kockelmann
authors.forename: Peter G
authors.initials: PG
authors.lastname: Bruce