Abstract
Controlling the morphology and magnetic properties of CoFe2O4 nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe2O4 nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe2O4 nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe2O4 nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe2O4 nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe2O4 nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe2O4 nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe2O4 nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe2O4 magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.
Highlights
Magnetic nanoparticles are very attractive for many applications in various fields, among which the iron oxide (Fe3 O4 ) nanoparticles have been widely studied in the past decade due to their outstanding ability to capture the magnetic moment signal, high biocompatibility, and high chemical stability [1,2]
Magnetic ferrite nanoparticles have other transition metal atoms such as Ni, Cu, Mg, Zn, Co, and Mn instead of some iron atoms in the ferrite crystal lattice and have gained remarkable attention in recent years because of their improved unique physicochemical properties such as a high surface area-to-volume ratio, feasibility of surface functionalization, and excellent magnetic responses with magnetic fields and field gradients that can be widely applied to bio-separation, magnetic resonance imaging, biosensors, drug delivery, and magnetic hyperthermia [3,4,5,6,7,8,9,10]
As the reaction time increased to 8–16 h, the intensity of those peaks increased remarkably, which means that the crystallinity of
Summary
Magnetic nanoparticles are very attractive for many applications in various fields, among which the iron oxide (Fe3 O4 ) nanoparticles have been widely studied in the past decade due to their outstanding ability to capture the magnetic moment signal, high biocompatibility, and high chemical stability [1,2]. The solvothermal methods have become popular and widely used to synthesize ferrite nanomaterials due to their simplicity, low cost, high potential on a large-scale fabrication, and, more importantly, high uniformity in both size and shape with excellent magnetic properties of the synthesized nanoparticles [25]. It is still a great challenge to controllably synthesize the CoFe2 O4 nanoparticles of desired size, shape, and properties for proposed application, because a small difference in synthesis process’ conditions might eventually cause a remarkable variation of product particle morphologies and characteristics. This will require a comprehensive study about the effects of synthesis process variables on the products. CoFe2 O4 nanoparticles, because the particle morphology control is strictly required to synthesize highly uniform products with desired properties for proposed applications
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