Surface-protective assistance of ultrasound in synthesis of superparamagnetic magnetite nanoparticles and in preparation of mono-core magnetite-silica nanocomposites

Ultrasound was throughout employed to enhance the co-precipitation process for the synthesis of magnetite nanoparticles (Fe 3 O 4 ) and the Stöber approach for the preparation of magnetite-silica nanocomposites (Fe 3 O 4 /SiO 2 ). The synthesised magnetite nanoparticles exhibited single-domain nanocrystallites with a uniform spherical morphology, a narrow size distribution (ca. 10 nm), and negligible coercive field (∼5 Oe). The prepared magnetite-silica nanocomposites possessed a mono core-shell structure with spherical morphology, biologically coherent size (ca. 100 nm), and discrete mono-domain behaviour. The crystalline structure-magnetic behaviour relationships of the nanomaterials were investigated to imply the presence of a surface protection at nanoscale. The speculation indicated that shock waves took place as the surface-protective role rather than the original mechanical interaction of ultrasound with a larger scope of impact.