Synthesis, characterization and magnetic properties of near monodisperse Fe3O4 sub-microspheres

Abstract

Near monodisperse Fe 3 O 4 sub-microspheres with an average diameter of 170 nm have been synthesized by a solvothermal reduction method, using K 3 [Fe(CN) 6 ] as the raw material in the absence of any surfactants at 200℃ for 24 h. The products were detected by XRD, FESEM, TEM, and XPS. The investigation of the reaction parameters indicates that ethylene glycol plays a key role both as reducing agent and solvent. In addition, the reaction time and temperature also have important influences on the final product. The hysteresis loop of the near monodisperse Fe 3 O 4 sub-microspheres shows a ferromagnetic behavior with saturation magnetization of 60.8 emu/g and coercivity of 124.7 Oe. solvothermal, sub-microspheres, morphology, saturation magnetizationIn recent years, increasing attention has been paid to the morphology and size control of materials synthesized on the micro-and nano-scale due to the fact that morphology and size play very important roles in determining chemical and physical properties of materials. As a type of important functional materials, iron oxides such as γ-Fe 2 O 3 and Fe 3 O 4 are becoming more and more attractive because of their intrinsic half-metallic ferromagnetic nature, which can be widely used in catalysts, biological assays, chemical sensors, ferrofluids, colored pigments, high density magnetic recording media, super paramagnets, etc. [1][2][3][4][5][6][7] . Because of the widespread applications, much attention has been paid to the preparation of different kinds of magnetic nanoparticles in the past dozens of years. To date, a number of preparation methods for magnetic nanoparticles have been developed, such as chemical co-precipitation [8] , oil-in-water emulsion [9] , sonochemistry [10] , spray pyrolysis [11] , hydrothermal [12] , solvothermal [13] , arc-discharge [14] , combustion synthesis [15] and thermal decomposition [16] . Although magnetic particles with narrow size distribution have been synthesized by various methods since the fabrication of monodisperse magnetic nanoparticles reported by Matijeviae in the early 1980s [17,18] , the products were overwhelmingly dominated by particles with sizes of dozens of nanometers. With the development of the modern science, it is an interesting challenge to develop approaches to synthesize magnetic particles with suitable sizes to meet the special need of biomedical fields. The research results indicate that various magnetic nano-or micro-particles have been considered as ideal candidates for biological applications such as protein and enzyme immobilization, cell isolation, DNA and RNA purification, immunoassay and guided site-specific drug delivery [19][20][21][22][23] , due to their good hydrophilic and biocompatible properties.Various chemical synthetic routes have been developed to synthesize monodisperse magnetite (Fe 3 O 4 ) particles. The main difficulty in synthesizing monodisperse Fe 3 O 4 particles is the intrinsic agglomerating properties of magnetic nanoparticles. Recently, in order to prevent this agglomeration, the synth...

Microemulsion-mediated hydrothermal growth of pagoda-like Fe3O4 microstructures and their application in a lithium–air battery

“…In the absence of the hydrazine, Fe 3 O 4 could not be obtained when other conditions were kept constant. This might be because hydrazine was able to slowly oxidize Fe 2 þ ions dissociated from [Fe(CN) 6 ] 4 À to Fe 3 þ ions under hydrothermal conditions in the reaction [22]. Fe 2 þ and Fe 3 þ contributed to Fe 3 O 4 , when hydrazine was used as the oxidant.…”

Controlling the size and size distribution of magnetite nanoparticles on carbon nanotubes

“…For example, Cai and Wan [18] have successfully synthesized Fe 3 O 4 nanoparticles in liquid polyols. Zhang et al [19] also reported the preparation of monodisperse Fe 3 O 4 sub-microspheres using ethylene glycol (EG) as both reducing agent and solvent. The advantages of polyols approach are the easily controlled experimental conditions, simplicity and less material consuming.…”

Synthesis and magnetic properties of Fe3O4/helical carbon nanofiber nanocomposites from the catalytic pyrolysis of ferrocene

“…On the other hand, the presence of a detrimental surface/ crystal-structure is also related to the demagnetization effects. However, the coercivity value is higher than that of sub-microspheres (124.7 Oe) and Fe 3 O 4 nanopartiicles (274 Oe) [25,26]. These research results indicate that size and morphology may be influencing factors because the coercivity is sensitive to many structural parameters such as the internal stress, the orientation, defects and shapes.…”