Synthesis of spherical iron-oxide nanoparticles of various sizes under different synthetic conditions

The present work describes eleven different syntheses of oleate-coated iron-oxide nanoparticles via thermolysis of Fe(III) oleate in high-boiling point organic solvents using a heating mantle with manual heating rate control. It has been shown that heating of iron oleate for 10 min in octadecane at 318 °C (average heating rate is about 7.7 °C/min) does not lead to the formation of iron-oxide nanoparticles, whereas decrease of the heating rate and further more continuous reflux (20, 30, 60 min) trigger their formation. The experimental results show that the use of heating mantle without automatic heating controller makes it harder to precisely control the size of the nanoparticles and indicate that certain variations of the heating rates may result in iron-oxide nanoparticles of slightly different sizes. It has been also exemplified that prehistory of the iron oleate namely its storage time may affect the morphology of the resulting iron-oxide nanoparticles.