ZnFe2O4@SiO2纳米核壳结构的合成及磁性随退火温度的演化

采用水热法合成了直径为10~15 nm的ZnFe2O4磁性纳米颗粒,将ZnFe2O4磁性纳米粒子添加到TEOS中,水解后得到ZnFe2O4@SiO2核壳结构的纳米复合材料,TEM图像证实了复合材料具有直径约为20 nm的核壳结构.制备出的ZnFe2O4磁性纳米粒子和ZnFe2O4@SiO2核壳结构纳米复合材料都表现出了顺磁性,温度低于800 ℃时ZnFe2O4磁性纳米粒子仍然具有顺磁性,温度高达580 ℃时ZnFe2O4@SiO2核壳结构纳米复合材料还是显示出了超顺磁性,这意味着ZnFe2O4和ZnFe2O4@SiO2磁性纳米粒子具有良好的磁稳定性.由于SiO2壳具有很好的亲水性和抗酸性,ZnFe2O4@SiO2核壳结构纳米复合材料未来可应用于磁疗法治疗癌症.

Preparation of ZnFe2O4@SiO2 core-shell nanocomposites and their magnetism evolution with annealing temperature

ZnFe2O4 magnetic nanoparticles with diameters between 10-15 nm were synthesized through a hydrothermal method.The ZnFe2O4@SiO2 core-shell structure nanocomposites were obtained by the hydrolysis of TEOS with the addition of ZnFe2O4 magnetic nanoparticles.The composites were further confirmed to have core-shell structure with diameters around 20 nm via TEM images.Both of the as-prepared ZnFe2O4 magnetic nanoparticles and ZnFe2O4@SiO2 core-shell structure nanocomposites showed paramagnetism.ZnFe2O4 magnetic nanoparticles possessed paramagnetism at temperature lower than 800 ℃.It was found that ZnFe2O4@SiO2 core-shell structure nanocomposites also showed superparamagnetism at temperature up to 580 ℃.This meaned that both the as-prepared ZnFe2O4 magnetic nanoparticles and ZnFe2O4@SiO2 core-shell structure nanocomposites had good magnetic stability.Since the SiO2 shell had the very good hydrophilicity and resistance to acid, ZnFe2O4@SiO2 core-shell structure nanocomposites might be applied to the magnetic therapy for the treatment of cancer in the future.