High-yield synthesis and characterization of monodisperse sub-microsized CoFe2O4 octahedra

In this study, sub-microsized CoFe₂O₄ octahedra with a high yield are synthesized via a simple hydrothermal route under mild conditions. The as-prepared products are characterized by conventional techniques of XRD, SEM, TEM, ED and HR-TEM. The results show that the as-synthesized sample exhibits octahedral morphology with a narrow size distribution. The edge size of CoFe₂O₄ octahedra is estimated to be about 0.10-0.14 μm. The growth process is also monitored by time and temperature-dependent observation. It is found that the reaction temperature has no obvious influence on the product morphology but a significant effect on the size of CoFe₂O₄ octahedra, while the reaction time determines the final morphology of the product. Moreover, it is displayed that the citrate ions play a key role in the formation of CoFe₂O₄ octahedra. Furthermore, the possible growth mechanism of the sub-microsized CoFe₂O₄ octahedra is discussed on the basis of a series of experiments. Magnetic measurements show that sub-micro-sized CoFe₂O₄ octahedra exhibit obvious ferromagnetic behaviors. The saturation magnetization (M_s), remanent magnetization (M_r), and coercivity (H_c) are determined to be 85.8, 29.2 emu/g and 892 Oe, respectively.