( 湖南大學 材料科學與工程學院， 長沙 410082)
摘 要: 通過溶膠凝膠法將NiFe2O4納米顆粒分散于SiO2基體中， 制得NiFe2O4/SiO2納米復合體。 利用XRD, DSC, TEM和VSM對合成的(NiFe2O4)wSiO2(1-w)(5%≤w≤55%)納米復合體進行了表征。 研究結(jié)果顯示： w＜15%的納米復合體均以非晶態(tài)存在， 在15%≤w≤50%的范圍內(nèi)， 隨著w的增加， NiFe2O4的晶粒尺寸從2 nm增長到25 nm， w進一步增加則會導致材料中NiFe2O4晶粒尺寸減小。 所制備的NiFe2O4/SiO2納米復合體的飽和磁場強度隨晶粒尺寸增加而增加， 變化范圍為3.7~11.0 A·m2·kg-1； 矯頑力值最大可以達到2.49×104 A·m-1， 是純NiFe2O4大塊材料矯頑力值的4倍以上。
關鍵字: 納米復合體; 溶膠凝膠法; 鎳鐵氧體; 二氧化硅基; 磁性能
nickel ferrite on silica nanocomposites
（ College of Materials Science and Engineering,
Hunan University, Changsha 410082, China）
Abstract: Nanocomposites with nickel ferrite nanoparticles uniformly dispersed in silica matrix were successfully synthesized by sol-gel process. The obtained (NiFe2O4)wSiO2(1-w)(5%≤w≤55%) samples were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscope (TEM) and vibration sample magnetometer (VSM). The results show that as w≤15%, the materials have an amorphous character, at the range of 15%≤w≤50%, the crystalline sizes increase ranging from 2 nm to 25 nm with increasing w, while at higher concentrations, a decrease in the crystalline sizes is observed. Ms increases with the crystalline size, ranging in 3.7-11.0 A·m2·kg-1 and coercivity can be as high as 2.49×104 A·m-1, which is more than four times higher than the coercivity of bulk nickel ferrite.
Key words: nanocomposites; sol-gel method; NiFe2O4; SiO2 matrix; magnetic properties
