高温高压下cBN单晶转变机理的EET理论分析  

EET Theory Analysis of the Transition Mechanism of cBN Single Crystal under HPHT

作　　者：许斌[1] 吕美哲 张文[1] 蔡立超[2] 苏海通 

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：《人工晶体学报》2015年第10期2714-2720,共7页Journal of Synthetic Crystals

基　　金：国家自然科学基金(51272139)

摘　　要：使用ab从头算原理计算了六方氮化硼(hBN)和立方氮化硼(cBN)在cBN单晶合成温度和压强下(1800K,5.0GPa)的晶格常数。通过EET理论构建了hBN和cBN的共价电子结构,并计算出九组hBN和cBN单晶的不同低指数晶面之间在高温高压下的相对共价电子密度。根据TFDC理论分析判断,发现hBN的(110)与cBN的(110)、hBN的(100)与cBN的(100)分别连续,两组晶面组合的相对共价电子密度差均小于<10%。这表明:这两组hBN/cBN晶面之间的价电子结构相差不大,可以诱使hBN直接转变为cBN。因此本文认为:从价电子结构的角度分析,高温高压下的cBN单晶极有可能是由hBN直接转变而来的。The principle of ab initio is used for the calculation of the lattice constants of hexagonal boron nitride （hBN） and cubic boron nitride （cBN） under cBN synthesis temperature and pressure （1800 K, 5.0 GPa）. By means of the EET theory, the covalent electronic structures of hBN and cBN could be constrctured, and the relative differences in covalent electron density were also calculated for the nine different combinations of low-index crystal planes of hBN and cBN. According to the TFDC theory, it is found that the lattice planes of （ll0） and （100） in hBN are consecutive with planes （110） and （100） of cBN respectively, and relative differences of the two sets in covalent electron density are much less than 10%. It shows that the small differences of covalent electronic structures at hBN/cBN adjacent crystal planes can induce the direct transition of hBN into cBN. This indicates that cBN is most likely to be transformed directly by the hBN under high temperature and high pressure （HPHT） from the perspective of covalent electronic structures.

关 键 词：EET理论 共价电子密度 cBN单晶 转变机理 高温高压 

分 类 号：O79[理学—晶体学]