Interplay between crystallization and particle growth during the isothermal annealing of colloidal iron oxide nanoparticles

Abstract

The relationship between crystallization and growth of colloidal iron oxide nanoparticles during isothermal annealing was addressed in this work. The structural, morphological and chemical modifications of the nanoparticles during thermal treatments were followed by combination of electron microscopy, X-ray diffraction and spectroscopic methods. The initially monodisperse spherical nanoparticles with amorphous and partially oxidized structure evolved during the treatments, depending on the temperature and treatment time. Core-void-shell nanoparticles or single crystal nanoparticles and hollow polycrystalline nanoparticles, both with well defined Fe(3)O(4) oxide phase, are formed depending on the conditions. This evolution was interpreted as a result of the Kirkendall effect associated to mass redistribution and fragmentation of the nanoparticles, bringing new information about the effect of post-synthesis treatments on the crystallinity and morphology of colloidal nanoparticles.

Nitric oxide donor superparamagnetic iron oxide nanoparticles

“…Such a kind of contrast may be related to differences in the mean atomic number of the material in these two regions, suggesting that the nanoparticles are formed by a Fe-oxide shell with an inner oxygen-poor core. This core-shell morphology is in agreement with the formation of Fe 3 O 4 during the synthesis [36].…”

Tuning the self-assembled monolayer formation on nanoparticle surfaces with different curvatures: Investigations on spherical silica particles and plane-crystal-shaped zirconia particles

“…Nanoparticle surfaces exhibit a high curvature with many defects and disordering phenomena. Furthermore very often particles show an amorphous outer-shell-formation at their surface which has to be taken into account if the surface is compared with an ideal crystal surface [35]. Also the number of surface OH-groups responsible for chemical bonding between organophosphorus anchor groups and the various oxidic nanoparticle surfaces usually differs from the coordination site number on a perfect plane surface [36], which has negative impact on the grafting density.…”

Hollow Magnetic Nanoparticles: Synthesis and Applications in Biomedicine

“…67 Principally, Atomic transport mode support the effect, as atoms diffuse through the interface, vacancies move in the opposite direction and accumulate to form void. 68 In recently years, magnetic hollow particles employing the Kirkendall effect based on the diffusion of pore and shell to provide void formation.…”