Influence of a silica interlayer on the structural and magnetic properties of sol-gel TiO₂-coated magnetic nanoparticles.
Superparamagnetic iron oxide nanoparticles coated with titanium dioxide have been synthesized, growing the titanium dioxide directly either on the magnetic nuclei or on magnetic nanoparticles previously coated with a semihydrophobic silica layer. Both coatings have been obtained by sol-gel. Since it is well-known that the existence of the intermediate silica layer influences the physicochemical properties of the material, a detailed characterization of both types of coatings has been carried out. The morphology, structure, and composition of the synthesized nanomatrices have been locally analyzed with subangstrom spatial resolution, by means of aberration corrected transmission electron microscopy (HRTEM and STEM-HAADF). Besides magnetization measurements, proton relaxivity experiments have been also performed on water suspensions of the as-synthesized nanoparticles to investigate the role of the silica interlayer in the relaxometric properties. The silica interlayer leads to nanoparticles with much higher water stability and to higher relaxivity of the suspensions.
Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza , Mariano Esquillor s/n, 50018 Zaragoza, Spain.
Laura
L
De Matteis
Rodrigo
R
Fernández-Pacheco
Laura
L
Custardoy
María L
ML
García-Martín
Jesús M
JM
de la Fuente
Clara
C
Marquina
M Ricardo
MR
Ibarra
D058185:Magnetite Nanoparticles / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
D058185:Magnetite Nanoparticles; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium