Reactivity of 3d Transition Metal Cations in Diethylene Glycol Solutions. Synthesis of Transition Metal Ferrites with the Structure of Discrete Nanoparticles Complexed with Long-Chain Carboxylate Anions

Abstract

Study of the reactivity of 3d transition metal cations in diethylene glycol solutions revealed several key features that made it possible to develop a new method for synthesis of the nanocrystalline transition metal ferrites. The 3-7 nm particles of [MFe2O4]n[O2CR]m, where M = Mn, Fe, Co, Ni, and Zn, ligated on their surface with long-chain carboxylate anions, have been obtained in an isolated yield of 75-90%. The key features are the following. Complexation of the first-row transition metal cations with diethylene glycol at a presence of alkaline hydroxide is sufficient to enable control over the rate of their hydrolysis. The reaction of hydrolysis leads to the formation of metal oxide nanocrystals in colloidal solution. The nanoparticles growth is terminated by an added long-chain carboxylic acid, which binds to their surface and acts as a capping ligand. The isolated nanocrystalline powders are stable against agglomeration and highly soluble in nonpolar organic solvents.

Magnetic properties of variable-sized Fe3O4nanoparticles synthesized from non-aqueous homogeneous solutions of polyols

“…Moreover, the presence of monolayers of polyol molecules adsorbed on the nanocrystals' surface induces their solubility in polar solvents such as water, methanol and ethanol. The polyol molecules can be exchanged at elevated temperatures for long-chain carboxylic acids which bind covalently to the surface iron ions via carboxylate groups, thereby stabilizing the particles against agglomeration and rendering them soluble in non-polar media (toluene, hexanes and decane) [31,32]. These fatty acids are also essential in minimizing the exchange interactions between the superficial iron ions of neighbouring Fe 3 O 4 nanocrystals such that the interparticle interactions are dominated by the dipole-dipole ones [33,34].…”

Cation distribution and magnetic behavior of Mg1 − x Zn x Fe2O4 ceramics monitored by Mössbauer Spectroscopy

“…ments [3,4], sensing materials [4][5][6][7], in high density memory devices, ferrofluid, drug carriers, and MRI contrast agents [8]. Magnesium ferrite (MgFe 2 O 4 ) is a soft magnet (space group Fd-3m) with low coercivities and high resistivities.…”

Magneto-optical spectra of closely spaced magnetite nanoparticles

“…Magnetite nanoparticles were synthesized using the method of Caruntu et al 15 Briefly, FeCl 3 and FeCl 2 were dissolved in diethylene glycol yielding a solution containing Fe 3+ and Fe 2+ ions in the ratio of 2:1. Coprecipitation with NaOH at ϳ200°C resulted in 8-10-nm Fe 3 O 4 particles.…”