Abdrie Seid Hassen: Using both species will give the same result. Lifehacks: 1) dissolve precursors (FeCl3 especially) in muriatic acid to prevent premature hydrolysis; 2) purge the alkali solution with nitrogen before reaction to prevent oxidation (to increase magnetite yield); 3) add some alcohol to alkali solution to decrease nanoparticles’ size.
Sadanand Pandey: According to stoichiometry, the ratio Fe(III):Fe(II) must be 2:1, not vice versa.