天然巴拉斯的结构特征——多晶金刚石的球体变体,Crystals

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天然巴拉斯的结构特征——多晶金刚石的球体变体
Crystals ( IF 2.4 ) Pub Date : 2023-04-05 , DOI: 10.3390/cryst13040624
Andrei A. Shiryaev _{1,

2} , Felix V. Kaminsky ₃ , Anton D. Pavlushin ₄ , Vasily O. Yapaskurt ₅ , Denis A. Zolotov ₆ , Alexei A. Averin ₁ , Olga M. Zhilicheva ₂ , Maximilian S. Nickolsky ₂ , Olga V. Kuznetsova ₃

Affiliation

巴拉斯 (Ballas) 是一种罕见的聚晶金刚石品种，其特点是内部结构呈放射状，外部形状呈球状。天然 ballases 的起源仍然没有得到很好的限制。我们展示了对产自巴西的两颗经典巴拉斯钻石进行全面调查的结果。使用 SEM、高分辨率 3D 光学显微镜和 X 射线断层扫描技术研究了外部形态。使用红外线、光和阴极发光光谱以及电子背散射衍射检查抛光中心板上的点缺陷和扩展缺陷；有关纳米夹杂物的信息是从透射电子显微镜中推断出来的。结果表明，包含巴拉斯的纤维状金刚石微晶随着明显的旋转而分裂，导致样品的同心分区。普遍的羽毛状发光结构特征包裹着单晶域，很可能代表具有非晶体分支的纤维。这些特征在 N3 点缺陷中得到了丰富。双胞胎并不常见。所研究样品的氮含量达到700 at.ppm；它的浓度从中心到边缘逐渐增加。球酶的退火发生在 1125–1250 °C 的相对高温下；正如外缘中存在与 H4 氮相关的缺陷所表明的那样，即使样品完全生长，退火仍在继续。据推测，巴拉斯钻石品种是在高过饱和度但有利于小生长动力学系数的条件下形成的。所研究的 ballases 的碳同位素组成 (δ13C = −5.42, −7.

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Structural Peculiarities of Natural Ballas—Spheroidal Variety of Polycrystalline Diamond

Ballas is a rare polycrystalline diamond variety characterized by a radially oriented internal structure and spheroidal outer shape. The origin of natural ballases remains poorly constrained. We present the results of a comprehensive investigation of two classic ballas diamonds from Brazil. External morphology was studied using SEM, high-resolution 3D optical microscopy, and X-ray tomography. Point and extended defects were examined on polished central plates using infra-red, photo- and cathodoluminescence spectroscopies, and electron back-scattering diffraction; information about nanosized inclusions was inferred from Transmission Electron Microscopy. The results suggest that fibrous diamond crystallites comprising ballas are split with pronounced rotation, causing concentric zoning of the samples. Pervasive feather-like luminescing structural features envelop single crystalline domains and most likely represent fibers with non-crystallographic branching. These features are enriched in N3 point defects. Twinning is not common. The nitrogen content of the studied samples reaches 700 at.ppm; its concentration gradually increases from the center to the rim. Annealing of the ballases took place at relatively high temperatures of 1125–1250 °C; the annealing continued even when the samples were fully grown, as suggested by the presence of the H4 nitrogen-related defects in the outer rim. Presumably, the ballas diamond variety was formed at high supersaturation but in conditions favoring a small growth kinetic coefficient. The carbon isotopic composition of the studied ballases (δ13C = −5.42, −7.11‰) belongs to the main mode of mantle-derived diamonds.

更新日期：2023-04-05

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