正二十面体金刚石的形成及其计算机模拟  

Formation of an icosahedral diamond crystal and its computer simulation

作　　者：余志明[1,2] 魏秋平[1] 叶浚[1] A. Flodrstrom 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]粉末冶金国家重点实验室,湖南长沙410083 [3]Royal Institute of Technology,Vahallavagen 79,SE-10044,Stockholm,Sweden

出　　处：《新型炭材料》2009年第2期102-108,共7页New Carbon Materials

基　　金：粉末冶金国家重点实验室开放基金(2008112048);湖南省研究生创新基金(1343-74236000005);中南大学优秀博士论文扶持基金(2008yb015);中南大学贵重仪器开放共享基金(ZKJ2008001)~~

摘　　要：采用热丝化学气相沉积(HFCVD)法,以甲烷和氢气为反应气体,在YG13(WC1-3%Co)硬质合金基体上制备了金刚石膜。膜中存在大量五重对称结构的正二十面体金刚石晶粒(IDC)。当尺寸较小时晶粒为较完整的正二十面体形状,尺寸达微米级后晶粒为带有"沟槽"或"凹坑"的变种正二十面体形状。研究了IDC的形成机制,并进行了计算机模拟。结果表明:对于四面体立方结构来说,IDC的{111}孪晶面与正常{111}孪晶面相比存在2.87o的差异,孪晶面两侧原子几何位置失配,使其成为畸变孪晶面,这种畸变孪晶面导致IDC晶粒存在"凹坑"和"沟槽";IDC的晶核是正十二面体烷(C20H20)。Icosahedral diamond crystals （IDCs） were found in chemical vapour deposited diamond by a field emission scanning electron microscope, using. YG13 （cemented tungsten carbide containing 13% of Co） as a substrate. It is found that the nanometer sized IDCs are in the shape of a nearly perfect icosahedron and the micrometer sized IDCs are in the shape of a icosahedron with dimples or grooves. A simulation on atomistic scale is performed by assuming a nucleation -growth model in order to elaborate the mechanism of IDC formation. Resuits show that the nucleus of IDCs is dodecahedrane, C20H20. For the tetrahedral cubic packing, the dihedral angle of {1 1 1} t facets of IDCs is 2.87° larger than that of the normal {1 1 1} twin plane. The geometric position of the bilateral atoms on the {1 1 1} twin plane of IDCs is mismatched, resulting in a distorted twin plane （DTP） in IDCs. The high energy of DTP induces the dimples or grooves that occurred in IDCs.

关 键 词：化学气相沉积 金刚石 正二十面体晶粒 十二面体烷 计算机模拟 

分 类 号：O613.71[理学—无机化学] TQ163[理学—化学]