【摘要】 利用共沉淀结合氢气还原法制备球形核-壳结构的γ-FeNi/SiO2纳米复合材料.用X射线衍射(XRD)确定样品的相组成,用透射电子显微镜(TEM)观察样品的形貌,用振动样品磁强计(VSM)测定样品的磁性能.结果表明:pH值是影响核-壳纳米结构形貌的重要因素;pH值为9左右且还原温度为700℃,制备出的纳米粒子具有近似的球形核-壳结构:纳米颗粒是以γ-FeNi合金为核心,其平均粒径大约为80 nm,外面包覆非晶SiO2壳层的核-壳结构;随着SiO2质量分数增加,样品的饱和磁化强度明显下降.随着还原温度升高,纳米粒子的尺寸大小略有增加,其饱和磁化强度明显增大,但矫顽力下降,这主要归结于铁镍与铁镍氧化物界面存在交换耦合相互作用.更多还原

【Abstract】 γ-FeNi/SiO2 with core-shell structure nanocomposites was prepared in co-precipitation combined H2 reduction method.The phase structure,morphology and magnetic properties of the nanoparticles were determined and measured by X-ray diffraction(XRD),transmission electron microscopy(TEM) and vibrating samples magnetometer(VSM),respectively.The result has shown that the pH is an important factor for core/shell nanostructure morphology.The TEM images have revealed that the nanoparticles reduced at 700 ℃ have an obvious core-shell structure at about pH 9.The core is γ-FeNi alloy with particles with an average diameter of about 80 nm and the coating shell is amorphous SiO2.It was found that the size of γ-FeNi nanoparticles increases little as the reduction temperature increases.Experiment results have indicated that the value of saturation magnetization decreases with the increase of the SiO2 content.The value of saturation magnetization increases with the increase of reduction temperature,but the coercive force decreases,due to the existence of the exchange coupling interaction interface of FeNi and Fe(Ni)-oxide.更多还原