摘要
利用场发射扫描电子显微镜（FESEM）和X射线能谱仪（EDS）研究了高温高压触媒法合成金刚石后金刚石/触媒界面的物相组成,发现铁镍元素与碳元素的原子比为3.1∶1,并分析得出高温高压下界面中存在Fe3C、Ni3C物相结构。据此,利用热力学中经典的ΔG〈0判定法,计算Me3C（Me：Fe,Ni）物相分解出金刚石的自由能变化。结果表明：在触媒法合成金刚石条件下（1500-1700 K、5-6 GPa）,Me3C C（金刚石）＋3Me比石墨金刚石的ΔG更负。因此,从热力学角度看,Me3C的形成,尤其是铁基触媒中Fe3C、Ni3C的形成,说明触媒法合成金刚石单晶是来自于Me3C型碳化物的分解,而并非石墨结构的直接转变。
During the synthesis of diamond with catalyst under high temperature and high pressure（HTHP）,the phase structures of diamond single crystal/metallic catalyst interface were investigated by field emission scanning electron microscope（FESEM） and energy dispersive spectrometer（EDS）.The results showed that the atomic ratio for（Fe＋Ni）/C are 3.1∶1,which means the Fe3C,Ni3C phase structure may exist on the diamond/metallic catalyst film interface at HTHP.In the next section the Gibbs free energy of the decomposition from Me3C-type（Me： Fe,Ni） phases to diamond were calculated with the determinant method of ΔG0 in thermodynamics theory.It was found that the Gibbs free energies of Me3CC（diamond）＋3Me is more negative than graphitediamond,which means the former will take place more easily at the range of 1500-1700 K,5-6 GPa.Therefore,from the viewpoint of thermodynamics,the formation of Me3C especially Fe3C and Ni3C explained the diamond crystal growth with catalysts comes from the decomposition of Me3C instead of the direct transformation from graphite structure to diamond structure.
出处
《人工晶体学报》
EI
CAS
CSCD
北大核心
2010年第6期1367-1371,1380,共6页
Journal of Synthetic Crystals
基金
国家自然科学基金(50972084)资助项目
山东省自然科学基金(ZR2010EM050)资助项目
