Two types of polymeric surfactants, PEG300
and PVP40000 , were used for the preparation of magnetic
ferrite MFe2O4 (M = Mn, Fe) colloidal nanocrystals using
a solvothermal reaction method. The effect of spinel type
effect on the size evolution of various nanoparticles was
investigated. It was found that Fe3O4 nanoparticles
exhibited higher crystalinity and size evolution than
MnFe2O4 nanoparticles with use of the two surfactants.
It is proposed that this observation is due to fewer
tendencies of surfactants on the surface of Fe3O4 building
blocks nanoparticles than MnFe2O4. Less amounts of
surfactant or capping agent on the surface of nanoparticles
lead to the higher crystalibity and larger size. It is also
suggested that the type of spinel (normal or inverted spinel)
plays a key role on the affinity of the polymeric surfactant
on the surface of building blocks
