Abstract:
Small-angle X-ray scattering (SAXS) was performed on a series of Electric Double-Layered Magnetic Fluids (EDL-MF) composed of ferrite type-- CoFe2O4, MnFe2O4, ZnFe2O4, NiFe2O4 and CuFe2O4--nanoparticles of different crystalline sizes ( D XR ranging from 40 to 139Å, as determined by X-ray diffraction). The information concerning the scattering objects was obtained through the analysis of the distance distribution function p(r) and of the size distribution function D(R), both retrieved from SAXS data. The results show that EDL-MF, in the absence of an applied magnetic field, are composed of small magnetic particle aggregates in solution. These agglomerates are elongated in one direction (chain-like) with the longest dimension varying from 240 to 330Å. The cross-section size is of the order of D XR. The data also demonstrate that the maximum dimension of these aggregates is independent of the ferrite type. On the other hand, the number of aggregated magnetic particles is nanoparticle-size-dependent. Accordingly, larger ferrite-type nanoparticles as those with D XR = 139Å form aggregates composed of 2-3 magnetic particles, whereas smaller ones with D XR 40Å form agglomerates of about 6 magnetic particles in solution. As the nanoparticle size is reduced, it might increase the particle surface defects. Such occurrence would affect the particle surface charge density, which could reduce the electrostatic screening, favoring the agglomeration phenomenon.
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Received 28 February 2000 and Received in final form 28 August 2000
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Itri, R., Depeyrot, J., Tourinho, F. et al. Nanoparticle chain-like formation in electrical double-layered magnetic fluids evidenced by small-angle X-ray scattering. Eur. Phys. J. E 4, 201–208 (2001). https://doi.org/10.1007/s101890170129
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DOI: https://doi.org/10.1007/s101890170129