温度梯度法宝石级金刚石的合成及表征  

Synthesis and characterization of the Gem-diamond by temperature gradient method

作　　者：肖宏宇[1] 苏剑峰[1] 张永胜[1] 鲍志刚[1] 

机构地区：[1]洛阳理工学院数理部,洛阳471023

出　　处：《物理学报》2012年第24期505-511,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50572032;50801030)资助的课题~~

摘　　要：利用温度梯度法,在5.0—5.7GPa,1250—1600℃条件下,研究了FeNiMnCo触媒合成宝石级金刚石的温度和压力区间,给出了P-T相图.基于有限元法的温度场模拟及碳素浓度梯度拟合结果表明,I型温度场只适合生长大尺寸优质板状及小尺寸塔状金刚石单晶;II型温度场可以合成出大尺寸优质板状或塔状金刚石单晶.该结论被Ib型及掺硼宝石级金刚石晶体生长实验所证实.提出碳素浓度梯度是决定晶体生长速度及合成晶体品质的关键因素.研究得到了只有触媒中温度场分布与晶体尺寸、形貌相匹配时,才能合成出优质宝石级金刚石单晶的晶体生长规律.揭示了{110}和{113}高指数晶面在Ib型金刚石"V"形区内的分布规律.通过傅里叶红外光谱检测发现,FeNiMnCo触媒合成金刚石的氮含量较低,较低的氮含量是由铁会降低金刚石氮含量所致.氮含量低有利于金刚石的光谱透过性.At pressure 5.0-5.7 GPa and temperature 1250-1600℃, the conditions of synthesis Gem-diamond are reported using FeNiMnCo catalyst by temperature gradient method （TGM）, and the P-T phase diagram is given. Temperature field and carbon concentration gradient are simulated based on finite element method （FEM）. The results of simulation and experiment show that type-I temperature field is suitable for growing high-quality large sheet-shaped Gem-diamond and small tower-shaped Gem-diamond; however, choosing type-II temperature field, both large sheet-shaped Gem-diamond and large tower-shaped Gem-diamond can be synthesized （type-Ib diamond and boron-doped diamond）. On this basis, the growth speed and crystal quality are found to be determined by the carbon concentration gradient, and the rule that high-quality Gem-diamond can be synthesized when temperature field is suitable for the size and shape of diamond growing is given. The pressure and temperature regions for {110} and {113} faces to exist are studied. According to the analysis of Fourier infrared spectroscopy, it is found that the nitrogen concentrations in type-Ib and boron-doped diamonds synthesized by FeNiMnCo catalyst, which are due to the influence of Fe element, are lower than that of normal diamond. The diamond with low nitrogen can be used as an optical material with better transmission characteristics.

关 键 词：金刚石 触媒 温度梯度法 有限元法 

分 类 号：TQ164[化学工程—高温制品工业]