对Fe-Ni-B催化剂合成的金刚石中含硼包裹物的研究

本文以自制的Fe基含硼合金作催化剂,石墨片作碳源,压力和温度分别为5.3GPa和1570K条件下,在六面顶压机上合成了0.6mm左右的含硼金刚石晶体.利用X射线衍射仪(XRD)分析了金刚石晶体的结构,证明金刚石是六方结构的.在光学显微镜下观察了金刚石的晶形,利用透射电子显微镜(TEM)和能谱仪(EDS)对金刚石晶体进行了微观分析,发现了多种含硼包裹物,包括(Fe,Ni)23(C,B)6,(Fe,Ni)3(C,B),(Fe,Ni)B,(Fe,Ni)2B,Ni3B,B4C等.研究了它们的化学组成与微观结构,并分析了含硼包裹物的来源与形成过程.结合金刚石的生长过程分析认为,合金触媒是金刚石中包裹物元素的主要来源,通过调整触媒的成份和含量可以控制金刚石内杂质元素的种类.硼元素在金刚石中既可以以化合物的形式存在,也可以替代碳原子存在于金刚石内.

Investigation on Boride Inclusions in Synthetic Diamond Grown from Fe-Ni-B Catalyst under HPHT

The outsourcing graphite discs were placed alternatively with several discs of Fe-Ni-B alloy catalyst. The high-temperature (1570K) and high-pressure (5.3GPa) experiment was carried out in a cubic anvil apparatus. The structure of synthetic diamond crystal was hexagonal, which was determined by X-ray diffraction.A optical microscope was used to observe the crystal shape of diamond and transmission electron microscopy (TEM) combined with energy dispersive X-ray spectrometer (EDS) was used to determine the microstructure of synthetic diamond crystal. Various borides inclusions were found in the diamond, such as (Fe,Ni)_(23)(C,B)_6, (Fe,Ni)_3(C,B), (Fe,Ni)B, (Fe,Ni)_2B, Ni_3B and B_4C. Their chemical composition and microstructures were investigated. And their origins and formation process were analyzed also. They are considered to form during the course of diamond growing and origin from the metal catalyst. The dopant in the diamond can be controlled via modulating composition and content of the metal catalyst. Boron can exist either as borides or as boron atoms substituting for carbon atoms.