Superparamagnetic Nanoparticles with Mesoporous Structure Prepared Through Hydrothermal Technique

摘要

Magnetite nanoparticles have been successfully prepared by hydrothermal method from FeCl_3 as starting material. The properties and morphology of the products with different synthesis time and FeCl_3 concentration were investigated. Firstly, the FeCl_3 with concentration of 0.05 - 0.15 M and 0.10 M sodium citrate as well as 0.15 M were mixed with distilled water containing 0.1 g polyethylene glycol. Subsequenly, the solution was transferred into a Teflon-lined autoclave and it heated into an oven at 210°C for 12 hours. The black precipitate that formed was separated by a bar magnet, then washed with water and ethanol, and dried at 60°C overnight. The magnetite formation begun at 3.5 hours synthesis time with crystal diameter in range of 9.4-30 nm. The crystallinity and crystal size of magnetite increased with reaction time and concentration of FeCl_3. The magnetite nanoparticles had a mesoporous structure and bigger pores at higher concentration. The saturation magnetization (Ms) of magnetite was in the range of 59 - 81 Emu/g with coercivity value was near to zero showing that magnetite nanoparticle had superparamagnetic properties.