A novel method was developed to fabricate monodispersed nanocomposite SiO2 sphere (200￣400 nm) containing homogeneously dispersed Ag nanoparticles (2￣6 nm). The morphology of inclusion was controlled through the N-[3-(Trimethoxysilyl)Propyl]ethylene diamine. TEM images showed that the silver nanoparticles were doped uniformly in silica spheres. UV-Vis showed that the doped silver nanoparticles have a plasmon resonance absorption band at 433 nm. Also SEM, EDX, XRD analyses were conducted to characterize thus-prepared sam- ples.
Nowadays, metallodielectric composite particles (especially spheres) have been the highlight to scientists due to their potential optical applications. In thi s paper, with wet chemistry method, we revised the Controlled-Double-Jet-Prec ipitation (CDJP) method and injected the silver salt and reducing agent into the silica-dispersed solution through two syringes. By changing the injected volum e and rate, we obtain silica/silver core/shell particles. TEM images show that t he silica surface was coated uniformly with silver nanoparticles and the samples were also uniform and low in polydispersity. Also XRD, EDX, DSC, UV-vis analys es were conducted to characterize thus-prepared samples.
A novel method of fabricating core-shell structure, comprising monodisperse polystyrene (PS) spheres as cores and Fe3O4 as shells, is demonstrated. The coating shell of magnetite (Fe3O4) crystallites was formed by controlled hydrolysis of aqueous solutions of iron ion with diethyleneglycol (DEG) either by the facile, electrostatic absorption between the polymer and iron compounds. Thickness of the shell could be easily changed in the range from 20 to 60 nm by using slow-injecting coating process. Structure and composition of iron compounds shell were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetric analysis (TG) and vibrating-sample magnetometer (VSM), indicating there are some differences between the Fe3O4-shell of the magnetic composite spheres and pure Fe3O4 particles, e.g. smaller crystallite size, lower magnetic transition temperature and weaker ferromagnetic character.
