Fe基金属包膜的Mssbauer参量及其在金刚石合成中的催化作用

MOSSBAUER PARAMETERS OF THE Fe-BASED METAL FILM SURROUNDING DIAMOND AND ITS CATALYTIC EFFECT DURING DIAMOND SYNTHESIS

研究了高温高压下金刚石单晶合成时形成的Fe基金属包膜与触媒合金的Mossbauer参量,并利用它们的差异,讨论了包膜的催化作用.结果表明,虽然Fe基金属包膜与触媒合金中的含Fe相均为γ-(Fe,Ni)和Fe3C,但包膜中的γ-(Fe,Ni)与触媒合金中的γ-(Fe,Ni)相比,同质异能移IS大于后者、超精细场Bhf小于后者.这表明Fe基金属包膜内γ-(Fe,Ni)中Fe原子的3d层电子状态发生了变化,包膜的γ-(Fe,Ni)在高温高压金刚石生长过程中是一催化相.

The Fe-based metal film surrounding diamond and solvent metal, formed during diamond synthesis at high temperature and high pressure (HPHT), have been investigated by means of Mossbauer spectroscopy, and the catalyzing mechanism of the film was studied from Mossbauer parameter differences between them. The results show that there are two phases containing iron atoms in both the film and the solvent metal. Compared the γ-(Fe, Ni) in the film with the γ-(Fe, Ni) in the solvent metal, the isomer shift (IS) in the former is higher than that in the later, and the hyperfine field (5hf) is lower. So it is believed that there must exist 3d-electrons transition in iron atoms in the γ-(Fe, Ni) in the film, from which the γ-(Fe, Ni) in the film could be thought as a catalyzing phase under diamond growth at HPHT.