本文研究了用高频溅射制备的纯Ｎｉ纳米晶体的晶格结构特征，利用Ｘ射线衍射技术精确测定了晶粒尺寸为６－１５ｎｍ的Ｎｉ纳米晶体的晶格常数．发现纳米晶体的晶格常数（ａ）均大于完整Ｎｉ单晶的平衡晶格常数（ａｏ），且ａ值随晶粒尺寸减小而显著增大，利用纳米晶体的热力学状态对这种晶格膨胀效应进行了解释． In this paper, the lattice structure of pure Ni nanocrystals prepared by high-frequency sputtering has been investigated. The lattice constants of Ni nanocrystals with grain sizes of 6-15nm have been accurately determined by X-ray diffraction. It is found that the lattice constant (a) of the nanocrystals is larger than the equilibrium lattice constant (ao) of the intact Ni single crystal, and the value of a increases remarkably with the decrease of the grain size. By using the thermodynamic state of the nanocrystals, The expansion effect is explained.