Optimization of Properties of Iron Oxide Nanoparticles Synthized by SolGel Method

In this study, the effects of pH value and capping agent on the morphology, pore structure and size of iron oxide nanoparticles were investigated systematically to obtain optimum properties. Iron oxide nanoparticles were synthized by sol-gel method. Polyvinyl alcohol (PVA) was used as capping agent by adding to the solution at 70 °C. After the drying process the powders were heat treated at 250 °C for 2 h under air atmosphere. Particle size of each sample was determined by using ZetaSizer instrument. X-ray diffraction (XRD) technique was employed for structural properties of iron oxide nanoparticles, FE-SEM (Field Emmision Scanning Electron Microscopy) was used to analyze the morphology of the powders. Magnetic properties of the nanoparticles were measured by VSM (Vibrating Sample Magnetometer) under air atmosphere at room temperature. Spesific surface area, porosity and pore size distribution of iron oxide nanoparticles were calculated by Brunauer-Emmett-Teller (BET) instrument. The results indicated that formation of the γ-Fe2O3 is sensitive to either the pH value of the solution or the capping agent, for the uncoated samples when pH value of the solution is adjusted to 2.5, α-Fe2O3 phase was detected as a single phase. When the solution was neutralized, γ-Fe2O3 was formed as the major phase in the microstructure, γ-Fe2O3 phase was formed as the major phase in the PVA coated samples leading to highest value of 50.33 emu/g measured in the sample of PVA8.5. For the PVA coated samples, specific surface area is in the range of 15.73 – 20.81 m2 /g, the intervals of pore volume and average pore width are increased to 0.099 – 0.121 cm3 /g and 23.19 – 23.07 nm respectively.