Influence of the Hollowness and Size Distribution on the Magnetic Properties of Fe₃O₄ Nanospheres

Abstract

In this study, Fe 3 O 4 nanospheres with different levels of hollowness were successfully prepared by the solvent thermal method. The synthesized Fe 3 O 4 nanospheres were characterized by transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry, and Image-Pro software was used to analyze the hollowness of the Fe 3 O 4 nanospheres for the first time. It was found that excess reactants could lead to the disappearance of the hollow structure of the Fe 3 O 4 nanospheres, and the reason for this phenomenon was discussed as due to entropy increase theory. Furthermore, the influence of the hollowness and size distribution on the magnetic properties of the Fe 3 O 4 nanospheres was evaluated. The magnetic properties of a Fe 3 O 4 nanosphere with a hollowness of 10.48% showed a relatively high saturation magnetization of 103 emu/g and a rather low coercivity (54 Oe). The as-prepared Fe 3 O 4 nanospheres are expected to be useful in a wide range of fields such as drug-delivery and energy applications.

Synthesis of Acid Mine Drainage (AMD) Sludge-Derived Al–Fe3O4 as Fenton-like Catalysts for the Efficient Degradation of Tetracycline

“…Moreover, the diffraction peaks at 2θ = 37.1°, 43.1°, 56.9°and 65.7°could be detected, corresponding to the crystal planes of ( 222), (400), ( 422), (511), and (531) of Fe 3 O 4 , which may be due to the deconstruction and transformation of FeOOH into Fe 3 O 4 under this pH condition. 29 Then the diffraction peaks of FeOOH completely disappeared at pH 10.03, and only the Fe 3 O 4 diffraction peak remained, proving the formation of Fe 3 O 4 with higher-purity crystal nuclei. It is well known that the crystal structure of maghemite (γ-Fe 2 O 3 ) is similar to that of Fe 3 O 4 , which leads to the XRD pattern being difficult to identify, but there is still a difference.…”