Magnetic Properties of Manganese Ferrite (MnFe2o4) Nanoparticles Synthesized by Co-Precipitation Method

Abstract

N anostructured transition metal oxides, also known as spinel ferrites, are commonly studied due to their potential use in a variety of biomedical applications such as magnetic resonance imaging, hyperthermia and targeted drug delivery [1]. The general formula for ferrite family is given as MFe 2 O 4 ; M=Zn, Ni, Co, Mn, where depending on the Curie temperature, magnetic anisotropy and magnetic moment of the substitution metal M, the overall magnetic properties of ferrites can be adjusted in order to optimize their performance in these biomedical applications. In this manner, manganese ferrite MnFe 2 O 4 is a good candidate with its relatively high magnetiza-tion and biocompatibility [2,3]. For these reasons, na-nosized MnFe 2 O 4 particles were deeply investigated in literature, where particles were synthesized with different techniques and their surfaces were functio-nalized with different capping agents. In the beginning of 2000s, Z. J. Zhang and co-workers, in a series of papers, showed the effect of particle size and interparticle interactions on the general magnetic behavior of MnFe 2 O 4 nanoparticles synthesized with reverse microemulsion method [4-7]. By grafting a wide variety of ligands on the surface of MnFe 2 O 4 nanoparticles, they also studied the relationship between surface coordination chemistry and the magnetic properties [8]. In 2009, A. Yang et al. demonstrated the change in Neel temperature depending on the cation distribution in MnFe 2 O 4 particles prepared with co-precipitation method [9]. Later Aslibeiki and his colleagues , reported observation of a superspin glass-like behavior in nanosized MnFe 2 O 4 particles produced by ball-milling technique, where they attribute the origin of this behavior to dipolar interactions among particles [10]. Following these studies, first papers reporting the implementation of MnFe 2 O 4 nanoparticles into biome-dical applications were published: Tromsdorf et al. [11] A B S T R A C T I n the presented study, manganese ferrite (MnFe 2 O 4) nanoparticles were synthesized by applying a modified co-precipitation method based on the decomposition of metallic precursors in a liquid phase environment in the presence of surfactant oleic acid. The synthesized sample was then characterized with X-ray Diffraction (XRD), standard and high resolution Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), which revealed that the as-prepared MnFe 2 O 4 particles are monodis-persed nanocrystals with an average size of 4.7 nm and well surrounded with dimeric oleic acid coating. The magnetic properties of nanoparticles were first investigated by means of Superconducting Quantum Interference Device (SQUID) magnetometry. The temperature and field dependent magnetization measurements showed that the MnFe 2 O 4 nano-particles exhibit superparamagnetic property with zero coercivity at room temperature and thermal irreversibility. The superparamagnetic behavior of MnFe 2 O 4 nanoparticles was further confirmed by conducting zero field Mössbauer Spectroscopy measurements on nanoparticle powders. As to fulfill all the requirements like crystallinity, small size and su-perparamagnetism, the prepared oleic acid coated MnFe 2 O 4 nanoparticles has the potential to be used in biomedical applications like targeted drug delivery, MRI and hyperthermia.