支撑团簇结构收缩效应的研究

Structure Shrinking of Supported Clusters

利用磁控溅射与液氮冷凝相结合的方法，分别在方华膜及金膜上制备了Ｃｕ、ＺｎＯ等团族样品；并对样品的微观结构进行了ＴＥＭ／ＥＤ观察。结果表明，当Ｃｕ团簇的直径为２ｎｍ时，它表现为非晶结构；而当其直径大于８ｎｍ时，则表现为晶体结构。具有晶体结构的Ｃｕ团簇晶格常数随其大小的不同，表现出不同程度的收缩效应，与块材相比，最大收缩量达到了５％。随着尺寸的变化，ＺｎＯ团簇也表现出了一定的晶格收缩，观察到的最大收缩量为７％。

Supported Cu and ZnO clusters on Formvar and Au foil are produced by using magnetron sputtering combined with liquid nitrogen condensation technique.Specimens are investigated by TEM/ED.Results show that,Cu clusters of 2nm in diameter are amorphous,and those larger than 8nm in diameter are in crystalline.For Cu clusters in crystal form,their lattice constan tends to shrink in different amount with the variation of cluster size,the largest shrinking value being 5% compared with that of bulk Cu.With the variation of cluster size,ZnO clusters also tend to shrink,the observed largest shrinking amount being 7% compared with that of bulk ZnO.