title: An X-ray absorption spectroscopy study of the inversion degree in zinc ferrite nanocrystals dispersed on a highly porous silica aerogel matrix.
abstract: The structural properties of zinc ferrite nanoparticles with spinel structure dispersed in a highly porous SiO(2) aerogel matrix were compared with a bulk zinc ferrite sample. In particular, the details of the cation distribution between the octahedral (B) and tetrahedral (A) sites of the spinel structure were determined using X-ray absorption spectroscopy. The analysis of both the X-ray absorption near edge structure and the extended X-ray absorption fine structure indicates that the degree of inversion of the zinc ferrite spinel structures varies with particle size. In particular, in the bulk microcrystalline sample, Zn(2+) ions are at the tetrahedral sites and trivalent Fe(3+) ions occupy octahedral sites (normal spinel). When particle size decreases, Zn(2+) ions are transferred to octahedral sites and the degree of inversion is found to increase as the nanoparticle size decreases. This is the first time that a variation of the degree of inversion with particle size is observed in ferrite nanoparticles grown within an aerogel matrix.
authors: Dipartimento di Scienze Chimiche e Geologiche, and INSTM, Università di Cagliari, S.S. 554, Bivio per Sestu, 09042 Monserrato (CA), Italy.
authors: D
authors: D
authors: Carta
authors: C
authors: C
authors: Marras
authors: D
authors: D
authors: Loche
authors: G
authors: G
authors: Mountjoy
authors: S I
authors: SI
authors: Ahmed
authors: A
authors: A
authors: Corrias
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D005782:Gels; C001215:ferrite; D012822:Silicon Dioxide; D015032:Zinc