Fe_3C型碳化物与人造金刚石晶面价电子结构分析  

ANALYSES FOR VALENCE ELECTRON STRUCTURES ON THE FACES OF SYNTHETIC DIAMOND CRYSTAL AND Fe_3C TYPE CARBIDES

作　　者：许斌[1] 宫建红[2] 李丽[2] 李木森[2] 宿庆财[2] 高洪吉[1] 

机构地区：[1]山东建筑大学材料科学与工程学院,济南250101 [2]山东大学材料科学与工程学院,济南250061

出　　处：《硅酸盐学报》2006年第6期656-661,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(50371048;50372035)资助项目

摘　　要：基于高温高压合成金刚石过程中铁基触媒及其金属包膜中存在大量Fe3C型碳化物的实验结果,利用余氏理论(empirical electron theory of solid and molecule,EET)分析了Fe3C型碳化物内C-C键组成晶面和与之对应的金刚石晶面的共价电子密度,发现它们在一级近似下存在连续性,满足程氏理论(improved Thomas-Fermi-Dirac theory advanced by Cheng,TFDC)提出的原子界面边界条件。分析结果表明:高温高压下的金刚石单晶生长与 Fe3C型碳化物的分解有关。在4种Fe3C型碳化物中,(Fe,Ni)3C内的C-C键组成晶面和与之对应的金刚石晶面的共价电子密度连续的组数最多。因而认为:合成金刚石过程中使用含镍的铁基触媒,在高温高压下形成的(Fe,Ni)3C作为碳源,最容易转变为金刚石。Based on a fact that there exist stacks of Fe3C type carbides in Fe-based catalyst and metal fill covering on diamond surface during synthesis of diamond at high temperature and high pressure （HPHT）, the covalent electron densities of the crystal faces composed of C-C bonds in the Fe3C type carbides were calculated according to the empirical electron theory of solid and molecule（EET）. It is found that they are very close to those corresponding to the crystal faces in diamond, which accord with the boundary condition （at first crder of approximation） from the improved Thomas-Fermi-Dirac theory advanced by Cheng Kaijia （TFDC）. Hereby, the results show that diamond growth at HPHT is closely related to decomposition of Fe3C type carbides. The number of continuous group of the covalent electron densities of the crystal faces of the diamond and composed of C-C bonds in （Fe,Ni）3C is the most among those of four types of Fe3C carbides. Therefore, diamond transformation is the most easy by using the Fe-based catalyst con- taining nicxel forming （Fe,Ni）3C as an carbon source at HPHT.

关 键 词：人造金刚石 渗碳体型碳化物 价电子结构 

分 类 号：TQ164[化学工程—高温制品工业]