The controlled synthesis of hollow magnetite (Fe₃O₄) nanospheres of varying sizes and structures was successfully obtained via a facile solvothermal process and varying cooling processes. The Fe₃O₄ nanospheres were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and superconducting quantum interference device magnetometry. The diameters of the as-synthesized nanospheres were controlled at around 500–700 nm by simply changing the cooling rate, which had an obvious influence on the morphology and magnetic properties of these Fe₃O₄ nanospheres. While a low cooling rate triggered the formation and extension of the cracks present in the Fe₃O₄ nanospheres, a sudden drop of temperature tended to favor multi-site nucleation of the crystals as well as the formation of compact and smooth hollow nanospheres with superior crystallinity and high saturation magnetization. The growth mechanism of hollow magnetite oxide nanospheres was proposed and the correlation between the structure and the magnetic properties of the hollow nanospheres was discussed, which promises the potential of the hollow nanospheres in various applications such as drug delivery and cell separation.

通过简便的溶剂热过程和不同的冷却过程成功地获得了具有不同大小和结构的空心磁铁矿（Fe ₃ O ₄）纳米球的受控合成。通过X射线衍射，透射电子显微镜，扫描电子显微镜和超导量子干涉仪磁力分析对Fe ₃ O ₄纳米球进行了表征。只需改变冷却速度，就可以将合成后的纳米球的直径控制在500-700 nm左右，这对这些Fe ₃ O ₄的形貌和磁性能有明显的影响。纳米球。虽然低冷却速率触发了Fe ₃ O ₄纳米球中裂纹的形成和扩展，但温度的突然下降往往有利于晶体的多位成核，并形成具有优异性能的致密，光滑的空心纳米球。结晶度和高饱和磁化强度。提出了中空氧化磁铁矿纳米球的生长机理，探讨了中空纳米球的结构与磁性之间的相关性，为中空纳米球在药物输送，细胞分离等多种应用中的潜力提供了可能。