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金刚石中过渡金属的研究现状 总被引：4，自引：0，他引：4
为了揭示金刚石的合成机理与过渡金属杂质离子对金刚石物理性质的影响，国内外展开了对合成金刚石及天然金刚石中镍，钴和铁等过渡金属杂质的实验与理论研究，各种吸收与发光光谱法和电子顺磁共振，被用于金刚石中过渡金属离子赋存状态的研究中，结果表明镍、钴离子可以间隙形式或替代方式进入晶格。 相似文献
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金刚石中晶格氢的UHF法计算分析 总被引：1，自引：0，他引：1
对金刚石中晶格氢进行了UHF法计算，结果表明，空穴吸引1～4个氢原子均可以稳定存在。空穴具有吸引较多氢原子在其周围的倾向，最多可以达到4个氢原子。当空穴吸引1个氢原子时，氢原子倾向于直接存在于碳晶格空穴中，不改变化学键的键长，即以顺磁性氢的状态存在时更为稳定。 相似文献
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介绍了矿物（金刚石）中电子－空穴心的形成机理，以及“心”对金刚石物化性质的改变。进而讨论了金刚石不等价类质同象产生的空穴心，可使金刚石具有极强的导热性和导电性。通过论述认为：金刚石的导电性是由空穴心引起的。 相似文献
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金刚石由于其独特的物理化学性质,在经济生产与科学研究中均具有重要价值.金刚石形成于地球大于150 km的深度范围内,是人类可以获得的来自地球深部地幔乃至核幔边界的最直接的样品,因此可以为研究地球深部物质组成和物理化学条件提供重要的素材.金刚石由碳元素组成,还含有微量的杂质元素（如氮、硼、氢、氧等）,其中氮和硼元素对于划分金刚石的晶体结构类型发挥着重要的作用.根据金刚石的产出类型,金刚石可以划分为幔源型、超高压变质型、陨石相关型以及蛇绿岩型金刚石.全球约百分之一的幔源型金刚石含有包裹体,对这些包裹体的研究显示,金刚石主要来源于地球150~200 km深度的岩石圈地幔.这些含有包裹体的金刚石中,仅有1%的金刚石来自于地球深部的软流圈、地幔过渡带、下地幔、甚至核幔边界.我国的金刚石产出类型多样,但是,目前仅山东蒙阴、辽宁复县的金伯利岩矿床以及湖南沅水的砂矿具有经济价值.蛇绿岩型金刚石是近年来金刚石研究领域取得的重要进展,该类型金刚石分布在全球多个造山带不同时代、不同构造属性的蛇绿岩地幔橄榄岩和铬铁矿中,被认为是一种新的金刚石的产出类型.相对于其他国家和地区的金刚石的研究,我国的金刚石领域的研究程度相对较低,缺乏对金刚石结构、化学组成以及包裹体组成的系统研究,制约了对我国金刚石成因的认识,限制了我国的金刚石的找矿工作.因此,亟需结合先进的分析手段对我国的金刚石及其围岩做进一步的研究,以期揭示金刚石的形成过程,为金刚石的找矿提供理论基础. 相似文献
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大量的事实早已证明，用静压法生产人造金刚石与使用的触媒有着密切的关系。近几年来又发现，合成金刚石的性质和单次产量除了与触媒的主要组元有关之外，在触媒中添加少量的硼也能对其产生明显的影响。1975年，我国成功地用含硼触媒合成出了耐热、高强度、化学惰性好的优良金刚石新品种——含硼黑金刚石。本文就硼对合成金刚石的作用，归纳整理了近几年来国内外所得的主要有关数据，并对各种理论上的解释作简要的概述。 相似文献
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Ⅰa型金刚石是世界上最重要的金刚石种类,约占金刚石总量的98%。利用大腔体压机通过优化温度、压力和时间等因素改善工业用途的Ⅰa型褐色金刚石的体色,是提高其经济价值并满足日益加剧的彩色金刚石市场需求的重要技术手段。但由于受金刚石原料的来源及实验技术条件的限制导致国内高温高压环境下对褐色金刚石的改色处理进展缓慢,并且改色后的金刚石很难达到宝石级别。本文对自20世纪60年代以来国内外对Ⅰa型金刚石高温高压(HTHP)改色处理的研究及所取得的成果进行了总结。已有的研究显示,在伴有塑性变形的基础上,不同结构的杂质氮是主要的致色元素。根据高温高压环境下Ⅰa型褐色金刚石内部杂质氮反应原理以及动力学机理,提出只要设计合理的样品组装方式以及恰当的改色处理所需的温压条件,我国普遍使用的六面顶压机同样具备对Ⅰa型褐色金刚石进行商业化改色处理的潜力。 相似文献
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金刚石中的氢及其在金刚石高温高压合成中的意义 总被引：1，自引：0，他引：1
氢在金刚石中往往以一定的化学态形式存在,不同类型的金刚石中氢会以不同的电荷状态进行迁移与扩散,也可以与其他杂质元素N、B、P等作用,形成(N,H)、(B,H)、(P,H)对;为高温高压合成金刚石的物质体系中引入氢,有利于提高高温高压合成金刚石的产量、粒度及品级,也将为模拟天然金刚石的形成与探讨地球深部的动力学过程提供科学线索。 相似文献
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The relationship between the distribution of nitrogen impurity centres in diamond crystals and their internal structure and mechanism of growth 总被引：1，自引：0，他引：1
Fifty diamond crystals of different morphological types (octahedra, dodecahedroids, cubes and single tetrahexahedroid) with differing internal structures were examined using methods of cathodoluminescence (CL), anomalous birefringence and local infrared (IR) analysis. The main objective of the study was to examine the regularities of nitrogen impurity distribution in diamond with differing internal structures. Almost all the analyzed octahedra, as well as dodecahedroids with zonal structures and the blocky dodecahedroids, are characterized either by nearly isothermic growth conditions or by a decrease in formation temperature during the crystallization process. In contrast to zoned octahedra and dodecahedroids, dodecahedroids with zonal–sectorial and sectorial internal structures show a notably different distribution of nitrogen defects, with Ntot generally decreasing from crystal cores to marginal areas, and degree of nitrogen aggregation increasing in the same direction. From this, it would follow that in these crystals, the temperature of diamond formation of the outer crystal zones is approximately 40–50 °C higher than that of the inner zones. The same result (15 to 80 °C) was obtained for diamond crystals with cubic habit, which generally show a fibrous internal structure, reflecting normal mechanisms of growth. The anomalous distribution of nitrogen centres in diamond crystals that grew through the normal mechanism, with a high rate of growth and in an oversaturated medium, might point to non-equilibrium relationships between the concentrations of different nitrogen centres. It is likely that in crystals of this type, the rate of growth is higher than the rate of structural nitrogen aggregation. Thus, it appears that in these peculiar crystals of diamond we deal with non-equilibrium concentrations of nitrogen B centres and, consequently, with anomalous, non-actual diamond formation temperatures. 相似文献
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A.P. Smelov V.S. Shatsky A.L. Ragozin V.N. Reutskii A.E. Molotkov 《Russian Geology and Geophysics》2012,53(10):1012-1022
Diamond from metaultramafic rocks of the Mesoarchean (2.96–3.0 Ga) Olondo greenstone belt, located in the western Aldan–Stanovoy shield, has been studied. Diamonds occur in lenses of olivine–serpentine–talc rocks within metaultramafic rocks of intrusive habit, whose composition corresponds to peridotite komatiites. All diamonds from the metaultramafic rocks are crystal fragments 0.3 to 0.5 mm in size. Morphological examination has revealed laminar octahedra, their transitional forms to dodecahedroids, crystals with polycentric faces, and spinel twins. The crystals vary in photoluminescence color: dark blue, green, yellow, red, or albescent. Characteristic absorption bands in crystals point to nitrogen impurities in the form of A and B1 defects and tabular B2 defects. The crystals studied belong to the IaA/B type, common among natural diamonds. The overall nitrogen content varies from < 100 to 3800 ppm. The relative content of nitrogen in B1 centers varies from 0 to 94%, pointing to long stay in the mantle. The carbon isotope ratio in the diamonds, 13C = ? 26‰, is indicative of involvement of subducted crust matter in diamond formation in the Archean. 相似文献
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E. M. Galimov O. V. Palazhchenko E. M. Verichev V. K. Garanin N. N. Golovin 《Geochemistry International》2008,46(10):961-970
The first data are reported on the carbon isotopic composition of diamond crystals from the Grib pipe kimberlite deposit of the Archangelsk diamond province (ADP). The δ13C value of the crystals ranges from ?2.79 to ?9.61‰. The isotopic composition of carbon was determined in three zoned crystals (δ13C of ?5.8 ?6.96 ‰, ?5.64/ ?5.85 ‰, and ?5.94/ ?5.69 ‰), two “diamond in diamond” samples (diamond inclusion with δ13C of ?4.05 and ?6.34 ‰ in host diamond crystals with δ13C of ?8.05 and ?7.54 ‰, respectively), and two samples of coated diamonds (cores with δ13C of ?6.98 and ?6.78‰ and coats with δ13C of ?7.51 and ?8.01 ‰, respectively). δ13C values were obtained for individual diamond crystals from bort-type aggregates (δ13C of ?4.24/ ?4.05 ‰, ?6.58/ ?7.48 ‰, and ?5.48/ ?6.08 ‰). Correlations were examined between the carbon isotopic composition of diamonds and their crystal morphology; the color; the concentration of nitrogen, hydrogen, and platelet defects; and mineral inclusions content. It was supposed that the observed δ13C variations in the crystals are most likely related to the fractionation of carbon isotopes rather than to the heterogeneity of carbon sources involved in diamond formation. The isotopic characteristics of diamonds from the Grib pipe were compared with those of previously investigated diamonds from the Lomonosov deposit. It was found that diamonds from these relatively closely spaced kimberlite fields are different; this also indicates the existence of spatially localized peculiarities of isotope fractionation in processes accompanying diamond formation. 相似文献
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湖南金刚石内部不均一性特征研究 总被引：1，自引：0，他引：1
将湖南金刚石加工成片，利用宝石显微镜，偏光镜，阴极发光（CL）仪和傅里叶红外光谱（FTIR）仪对其内部显微特征进行了研究，发现金刚石的颜色深浅不一，内外颜色差异明显，呈带状，斑状分布；金刚石由生长中心至边缘，氮含量也有较大变化，中心与边缘最大相差约50倍，氮的富集类型由中心向边缘表现出B中心所占的比例越来越小，金刚石的类型也相应从I型→II型或I－aAB型→-I-aA型等，这些不均一性特征，反映金刚石在生长过程中环境条件发生了变化，以及生长期后可能受到了改造。 相似文献
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金刚石的微区显微红外光谱分析及其意义 总被引：7，自引：3，他引：7
金刚石的微区显微红外光谱分析表明：金刚石的形成是一个结晶物化条件变异，原始物质变换的复杂而又漫长的过程；杂质N、H等在其中的分布不均匀；同一晶体的中心部位其氮聚合态的转变时间与边缘相差约602Ma；金刚石中的成键氢以对应－CH3的C－H键形式存在要比对应于＞C＝CH2的C－H键形式存在更为广泛。利用红外光谱研究晶化固态物质必须强调定向及微区研究的意义。 相似文献
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Lutz Nasdala Dieter Grambole Manfred Wildner Alexander M. Gigler Thomas Hainschwang Alexander M. Zaitsev Jeffrey W. Harris Judith Milledge Daniel J. Schulze Wolfgang Hofmeister Walter A. Balmer 《Contributions to Mineralogy and Petrology》2013,165(5):843-861
We have undertaken a study of the common green or orange-brown spots at the surface of rough diamond specimens, which are caused by alpha particles emanating from radioactive sources outside the diamond. Richly coloured haloes represent elevated levels of structural damage, indicated by strong broadening of the main Raman band of diamond, intense strain birefringence, and up-doming of spots due to their extensive volume expansion. Green radio-colouration was analogously generated through the irradiation of diamond with 8.8 MeV helium ions. The generation of readily visible radio-colouration was observed after irradiating diamond with ≥1015 He ions per cm2. The accumulation of such a high number of alpha particles requires irradiation of the diamond from a radioactive source over long periods of time, presumably hundreds of millions of years in many cases. In the samples irradiated with He ions, amorphisation was observed in volume areas where the defect density exceeded 5 × 10?3 Å?3 (or 0.03 dpa; displacements per target atom). In contrast, graphitisation as a direct result of the ion irradiation was not observed. The green colouration transformed to brown at moderate annealing temperatures (here 450 °C). The colour transformation is associated with only partial recovery of the radiation damage. The colour change is mainly due to the destruction of the GR1 centre, explained by trapping of vacancies at A defects to form the H3 centre. An activation energy of ~2.4 ± 0.2 eV was determined for the GR1 reduction. The H3 centre, in turn, causes intense yellowish-green photoluminescence under ultraviolet illumination. Radio-colouration and associated H3 photoluminescence are due to point defects created by the ions irradiated, whereas lattice ionisation is of minor importance. This is concluded from the depth distribution of the colouration and the photoluminescence intensity (which corresponds to the defect density but not the ionisation distribution pattern). The effect of the implanted He ions themselves on the colour and photoluminescence seems to be negligible, as radio-colouration and H3 emission were analogously produced through irradiation of diamond with C ions. The photoluminescence emission becomes observable at extremely low defect densities on the order of 10?6 Å?3 (or 0.000006 dpa) and is suppressed at moderate defect densities of ~5 × 10?4 Å?3 (or ~0.003 dpa). Intensely brown-coloured diamond hence does not show the H3 emission anymore. Anneals up to 1,600 °C has reduced considerably irradiation damage and radio-colouration, but the structural reconstitution of the diamond (and its de-colouration) was still incomplete. 相似文献
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同步辐射白光形貌术具有射线强度大、准直性好、摄谱时间短、分辨率高等特点,是无损研究晶体缺陷的有效工具．采用该方法对产自山东蒙阴、辽宁瓦房店和湖南沅江3个矿区的31颗典型金刚石样品进行了研究．白光形貌像揭示,金刚石中普遍存在晶体结构畸变的特征,并且变形程度不等,部分严重变形晶体具有异常劳埃衍射式样;其衍射斑点的形态、衬度及条纹变化反映了金刚石晶体结构变形的程度和复杂性．晶格的完整性与金刚石的褐色强度无明显相关性．该类结构缺陷与金刚石的复杂形成过程和深部保存条件有关． 相似文献
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I. N. Bogush Z. V. Spetsius O. E. Koval’chuk B. S. Pomazanskiy 《Geochemistry International》2016,54(8):681-690
FTIR microspectroscopic data were used to construct two-dimension maps showing the distribution of structural impurities and mineral microinclusions in cubic and coated octahedral diamond crystals from the Udachnaya kimberlite pipe in Yakutia. Elevated concentrations of hydrogen and total nitrogen are detected in parts corresponding to the early growth of single-episode growth regions of diamond crystals. These concentrations decrease toward the peripheral portions of these regions. The microinclusions contain water and polyphase mineral associations that preserve a high residual pressure. Microinclusions in the coats of octahedral diamond crystals are dominated by silicates, in which the intensity of IR spectral bands increases toward the peripheries, whereas the cubes posses irregularly distributed domains rich in these phases. The carbonate phases of the microinclusions are distributed according to growth zones of the crystals, and their distribution is often not correlated with the concentrations of structural impurities. The facts that microinclusions in the diamond cuboids are dominated by carbonates and that the rims of the octahedra are dominated by silicates suggest that the diamonds crystallized from dominantly carbonate and silicate fluids/ melts, respectively. The chemical composition of the microinclusions point to an eclogitic paragenesis of the crystals. Facts are obtained that provide support for the earlier hypothesis that cubic diamond crystals and coated octahedral crystals grow at metasomatic interaction between deep fluids and eclogitic rocks in the lithospheric mantle. 相似文献