铁基触媒合成金刚石形成的金属包膜成分的研究

利用电子探针(EPMA)和X射线光电子能谱(XPS)研究了包围金刚石单晶的铁基金属包膜和触媒的成分分布。结果表明，在金刚石生长过程中，接近金刚石单晶的包膜内层中的碳含量是变化的，但均高于接近金刚石的触媒层。然而，与包围金刚石单晶的触媒表面相比，包膜表面碳含量低、铁含量高。分析认为，高温高压下，金刚石生长的碳源主要来自于包膜，但碳并非均匀地在包膜熔体内层向金刚石扩散。结合前期研究发现的“包膜内层无石墨和无定形碳结构”的事实分析，金刚石生长所需的碳极有可能来源于包膜内层铁碳化物的瞬间分解，结果导致包膜表面瞬间碳含量低、铁含量高。

STUDY ON COMPOSITION OF THE METALLIC FILM DURING SYNTHETIC DIAMOND GROWTH FROM Fe - Ni - C SYSTEM

Composition distributions in metallic film and solvent metal surrounding on the as-grown single diamond synthesized from FeNiC system at high temperature and high pressure (HTHP) were investigated using electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The results show that carbon content in the film adjacent to diamond (called the inner layer) are changing under the process of diamond growth, and it is higher than that in the solvent metal adjacent to diamond. However, compared with those on the solvent metal, there exist lower carbon and higher iron contents on the film contacting diamond. Carbon atoms in the inner layer are considered to be the main source for diamond growth, but they are diffusing discontinuously towards the growing diamond at HPHT. According to the results and previous findings of no graphite and amorphous carbon in the inner layer, carbon atoms for diamond growth may come from the instant decomposition of iron carbides in the inner layer during the diamond growth, which results in lower carbon and higher iron contents on the film than those on the solvent metal at a moment.