Abstract:We report on experimental observations of self-assemblies in colloidal dispersions of clay nanoplatelets and magnetic nanoparticles. Visual observations have been combined with small angle X-ray scattering (SAXS) in the study of several composites at a fixed clay concentration in the dilute regime, and varying ferrofluid concentrations. Our visual observations which encompass macroscopic separation in gravitational-and magnetic field, indicate that all samples present a concentrated phase and a diluted one. SA… Show more
“…This work aims to investigate the local structure of magnetic colloids [22] under external magnetic field application, the colloids in question are composed of magnetic nanoparticles based on manganese ferrite type core-shell MnFe 2 O 4+δ @γ-Fe 2 O 3 [23] and dispersed in aqueous medium. SAXS measurements were performed with external magnetic field applied [24] to determine the dimensions between nanoparticles and clusters [25], for future studies in hyperthermia [26] for biomedical applications.…”
In this work, we investigated the local colloidal structure of ferrofluid, in the presence of the external magnetic field. The nanoparticles studied here are of the core-shell type, with the core formed by manganese ferrite and maghemite shell, and were synthesized by the coprecipitation method in alkaline medium. Measures of Small Angle X-ray Scattering (SAXS) performed in the Brazilian Synchrotron Light Laboratory (LNLS) were used for the study of the local colloidal structure of ferrofluid, so it was possible to study two levels of structure, cluster and isolated particles, in the regimes with and without applied magnetic field. In the methodology used here there is a combination of the information obtained in the system with and without magnetic field application. In this way, it is possible to undertake a better investigation of the colloidal dispersion. The theoretical formalism used: (i) the unification equation proposed by Beaucage G.; (ii) the analysis of the radial distribution function p ( r ) and (iii) theoretical calculation of the radius of gyration as a function of the moment of inertia of the spherical of n-nanoparticles.
“…This work aims to investigate the local structure of magnetic colloids [22] under external magnetic field application, the colloids in question are composed of magnetic nanoparticles based on manganese ferrite type core-shell MnFe 2 O 4+δ @γ-Fe 2 O 3 [23] and dispersed in aqueous medium. SAXS measurements were performed with external magnetic field applied [24] to determine the dimensions between nanoparticles and clusters [25], for future studies in hyperthermia [26] for biomedical applications.…”
In this work, we investigated the local colloidal structure of ferrofluid, in the presence of the external magnetic field. The nanoparticles studied here are of the core-shell type, with the core formed by manganese ferrite and maghemite shell, and were synthesized by the coprecipitation method in alkaline medium. Measures of Small Angle X-ray Scattering (SAXS) performed in the Brazilian Synchrotron Light Laboratory (LNLS) were used for the study of the local colloidal structure of ferrofluid, so it was possible to study two levels of structure, cluster and isolated particles, in the regimes with and without applied magnetic field. In the methodology used here there is a combination of the information obtained in the system with and without magnetic field application. In this way, it is possible to undertake a better investigation of the colloidal dispersion. The theoretical formalism used: (i) the unification equation proposed by Beaucage G.; (ii) the analysis of the radial distribution function p ( r ) and (iii) theoretical calculation of the radius of gyration as a function of the moment of inertia of the spherical of n-nanoparticles.
“…The ionic strength and pH conditions needed to obtain a stable isotropic liquid dispersion of magnetic nanoparticles and laponite nanoplatelets are described elsewhere (Paula et al, 2007). Our composite materials were obtained by mixing an isotropic liquid dispersion of laponite at 0.1 wt% and a ferrofluid solution with a fraction of magnetic nanoparticles of 0.025 wt%.…”
We investigated mixed colloidal dispersions of clay platelets and magnetic nanoparticles using small-angle X-ray and neutron scattering. Our results show that the contribution to the scattering is essentially due to the magnetic nanoparticles. The scattering intensities are proportional to the concentration of magnetic particles, indicating that from the scattering point of view the sample is a colloidal dispersion of non-interacting magnetic objects, although the laponite and magnetic particles clearly interact when the sample textures are observed in an optical microscope. The visually observed phase separation may be characterized as a liquid-gas transition.
“…Assim, considera-se esferas seguindo uma distribuição log-normal designada por 2 : onde σ é a polidispersão e D 0 é o diâmetro médio. O fator de forma é adaptado [66] em função da distribuição log-normal por:…”
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