Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles | Girgis et al. Nanoscale Research Letters 2011 6 460 http content 6 1 460 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Synthesis magnetic and optical properties of core shell SiO2 nanoparticles Emad Girgis1 4 Mohamed MS Wahsh2 Atef GM Othman2 Lokeshwar Bandhu3 and KV Rao3 Abstract The optical properties of multi-functionalized cobalt ferrite CoFe2O4 cobalt zinc ferrite and zinc ferrite ZnFe2O4 nanoparticles have been enhanced by coating them with silica shell using a modified Stober method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core shell ferrites nanoparticles have been fired at temperatures 400 C 600 C and 800 C respectively for 2 h. The composition phase and morphology of the prepared core shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy respectively. The diffuse reflectance and magnetic properties of the core shell ferrites nanoparticles at room temperature were investigated using UV VIS double-beam spectrophotometer and vibrating sample magnetometer respectively. It was found that by increasing the firing temperature from 400 C to 800 C the average crystallite size of the core shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800 C show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand core shell zinc ferrite silica nanoparticles fired at 400 C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core shell zinc ferrite silica nanostructures make them promising candidates for magneto-optical nanodevice applications. Keywords nanostructures oxides cobalt ferrite cobalt zinc ferrite zinc ferrite magnetic properties diffuse .
