溶胶-凝胶法制备CoFe₂O₄/SiO₂复合材料及其磁性研究

溶胶-凝胶法制备CoFe 2 O 4 /SiO 2 复合材料及其磁性研究 Synthesis and Magnetic Properties of CoFe 2 O 4 /SiO 2 Nano-Composites by Sol-Gel Method 张悦 ZHANG Yue 1 2 first-author 柳阳 LIU Yang 1 2 冯金地 FENG Jindi 1 2 石兢 SHI Jing 1 2 熊锐 XIONG Rui 1 2 武汉大学物理科学与技术学院 武汉大学物理科学与技术学院 School of Physics and Technology,Wuhan University School of Physics and Technology,Wuhan University 武汉大学物理科学与技术学院,湖北,武汉,430072 武汉大学物理科学与技术学院,湖北,武汉,430072 采用溶胶-凝胶法制备了CoFe2O4/SiO2纳米复合材料,利用X射线衍射,透射电镜以及傅立叶变换红外吸收光谱分析了该复合材料的结构、形貌及形成机理,并在室温下用振动样品磁强计测量了复合材料的磁滞回线.实验结果表明:当煅烧温度不超过1 250℃时,复合材料中的球型CoFe2O4纳米晶镶嵌在非晶SiO2基体中,纳米晶的平均尺寸从煅烧温度850℃时的5 nm缓慢增大到1 250℃时的35 nm;当煅烧温度升高到1 300℃时,SiO2的晶化导致了CoFe2O4纳米晶的严重团聚,CoFe2O4纳米颗粒的平均尺寸迅速增大到83 nm,CoFe2O4的晶体结构有所改变,饱和磁化强度急剧增大,矫顽力和剩磁比则显著下降.并且在1 250℃时,复合材料的矫顽力和剩磁比均达到最大值,分别为1.61 kOe和0.91.在850℃时,复合材料表现超顺磁性. CoFe2O4/SiO2 nano-composites were prepared by sol-gel method.The crystal structure,morphologies,and formation mechanism of the composites were studied through X-ray diffraction（XRD）,Fourier transform infrared（FT-IR） spectrum,and transmission electron microscope（TEM）.The magnetic hysteresis loops were collected using a vibrating sample magnetometer（VSM） at room temperature.The results show that as the calcining temperature is below 1 250 ℃,the composites compose of CoFe2O4 nano-crystallite dispersed in the amorphous SiO2 matrix,and the crystallite size increases slowly from 5 nm to 35 nm as the calcining temperature increases from 850 ℃ to 1 250 ℃.As the calcining temperature increases to 1 300 ℃,the crystallization of SiO2 results in a serious agglomeration of CoFe2O4 nanoparticles,and induces the crystal structure change from the normal spinel to mixing of normal spinel and inverse spinel,the drastic increase of Ms,and the considerable decrease of Hc and remanence ratio,at 1 250 ℃,both Hc and remanence ratio reach their maximum values of 1.61 kOe and 0.91 respectively.Furthermore,superparamagnetic behavior is observed in the nano-composites calcined at 850 ℃. CoFe2O4/SiO2纳米复合材料 溶胶-凝胶 结晶 磁性 CoFe2O4/SiO2 nano-composites sol-gel crystal structure magnetic properties TB332 国家自然科学基金（10674105）;国家重点基础研究发展（973）计划（2007CB607501）资助项目 2008-03-01 2021-04-01 3