Oriented graphite single-crystal inclusions in diamond
Oriented graphite single-crystal inclusions in diamond
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金刚石中的定向石墨单晶包裹体
DOI：
10.1524/zkri.218.11.733.20302
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Harris
中科院分区：
文献类型：
--
作者：
J. Glinnemann;K. Kusaka;J. Harris
本文对13个中心含有自面体单晶石墨包裹体的金刚石样品进行了结晶学研究。所有夹杂物都属于六方石墨变质(空间群p63/mm C；a0≈2.46？，c0≈6.70？)，直径可达300mGm。将测得的石墨晶体的c-晶格参数与等静压升高时的石墨晶格参数进行比较，发现夹杂物上的残余压力高达2.6 Gpa。所有样品都表现出明显的石墨和金刚石之间的取向关系。在12个样品中，石墨的[001]方向(G[001])大致平行于立方金刚石的一个<111>方向(D<111>)。最大偏差约为4°。这12个样品的进一步划分是：(A)三个G<100>方向与三个D<110>方向的夹角约为4°。在五个样品中观察到了这种取向关系。(B)在6个样品中，相同方向之间的夹角约为34°。(C)在一个样本中，该角度约为16°。在第13个样品中，G[001]与三个D<100>中的一个大致平行。偏差约为6°，其中一个G<100>方向与一个D<110>方向几乎平行。用“重合格点(CSL)”概念的简化应用对这些取向关系进行了分析。第14个样品与所有其他样品不同，因为它显示了一个很大的(约300μm边缘长度)区域，带有一个尖锐的六边形边界线，里面充满了由微小的石墨“岛”组成的“拼凑”。几个厚度达5μm的平行薄片形成六角锥体形式。这种石墨包裹体相对于钻石来说是原生的。
Abstract A crystallographic study of 13 specimens of diamonds with euhedral single-crystalline graphite inclusions in their centres is presented. All inclusions belong to the hexagonal graphite modification (space group P63/mmc; a0 ≈ 2.46 Å, c0 ≈ 6.70 Å) and are up to 300 μm in diameter. Comparison of the measured c-lattice parameters of the graphite crystals with lattice parameters of graphite at elevated isostatic pressures indicates remnant pressures of up to 2.6 GPa acting on the inclusions. All samples exhibit distinct orientation relations between graphite and diamond. In 12 samples the direction [001] of graphite (G[001]) approximately parallels one of the directions 〈111〉 of cubic diamond (D〈111〉). The largest deviation is about 4°. A further division of these 12 samples is: (a) The three G〈100〉 directions have angles of about 4° with three D〈110〉 directions. This orientation relation is observed in five samples. (b) The angle between the same directions is about 34° in six samples. (c) In one sample this angle is about 16°. In a 13th specimen G[001] approximately parallels one of the three D〈100〉. The deviation is of about 6°, and one of the G〈100〉 directions nearly parallels one of the D〈110〉. These orientation relations are analysed with a simplified application of the “coincidence site lattice (CSL)” concept. A 14th specimen is different to all others, as it exhibits a large (about 300 μm edge length) region with a sharp hexagonal borderline filled with a “patchwork” of tiny graphite “islands”. Several parallel lamellae of up to 5 μm thickness result in a hexagonal pyramidal form. This graphite inclusion is suggested to be protogenetic with respect to the diamond.