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采用溶胶—凝胶法制备了含Ni2 + 的SiO2 干凝胶 ,再通过化学还原得到了纳米Ni/SiO2 介孔复合体。从样品的透射电子显微镜观测结果可估算出 ,介孔复合体中Ni粒子的尺寸约为 11～ 12nm。样品的磁性测量结果表明 ,与通常的Ni纳米颗粒相比 ,纳米Ni/SiO2 介孔复合体中纳米Ni粒子的粒径在大于理论计算的纳米Ni粒子的临界尺寸时 ,仍能够保持超顺磁状态。在一定温度范围内 ,提高还原温度有利于复合体中纳米Ni粒子向超顺磁状态转变。
The SiO2 xerogel containing Ni2 + was prepared by sol-gel method and the nano-Ni / SiO2 mesoporous composite was obtained by chemical reduction. From the transmission electron microscopic observation of the sample, it can be estimated that the size of the Ni particles in the mesoporous composite is about 11 to 12 nm. The magnetic measurement results of the samples show that compared with the conventional Ni nanoparticles, the nano Ni particles in the nano-sized Ni / SiO2 mesoporous composite can still maintain the superparamagnetism when the particle size is larger than the critical size of the theoretically calculated nano Ni particles status. In a certain temperature range, increasing the reduction temperature is beneficial to the transformation of nano-Ni particles into superparamagnetic state in the composite.