密堆六方结构Ni纳米颗粒的合成及其磁性

采用溶胶-凝胶方法制备前驱体样品, 在氩气气氛中不同温度下热处理得到样品. 利用热分析仪、 X射线衍射(XRD)、 透射电子显微镜(TEM)和振动样品磁强计(VSM)研究材料的合成、 形貌、 结构及其磁性. 结果表明, 经300 ℃热处理的样品为具有密堆六方结构的球形Ni纳米颗粒, 且六方Ni单相具有铁磁性质, 平均晶粒尺寸即超顺磁临界尺寸约为12 nm, 室温下在-800~800 kA/m磁场范围内未表现出饱和趋势, 最大比磁化强度为0.58 (A·m2)/kg, 矫顽力为1.592 kA/m. 

Synthesis and Magnetic Properties of Hexagonal Close-packed Ni Nanoparticles

The hexagonal close-packed Ni nanoparticles were synthesized with the precursor prepared by sol-gel method via heat-treating technique in Ar atmosphere. The synthesis condition, structural and magnetic properties of the samples were analysed by means of thermogravimetric analysis (TG), different thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results indicate that hcp Ni nanoparticles with spheric shape were synthesized by heating precursor at 300 ℃. The average grain size of the hcp Ni particles is evaluated to be about 12 nm via Scherrer equation. The RT magnetic measurement in 800 kA/m field for the samples suggests the unsaturated magnetization in hcp nanoparticles. It turns out that the hcp Ni nanoparticles have unique ferromagnetic with a magnetization of 0.58 (A·m2)/kg and a coercivity of 1.592 kA/m. The critical size of superparamagnetic behavior is near to 12 nm.