共查询到16条相似文献,搜索用时 156 毫秒
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对山东郯城砂矿中的金刚石开展了傅里叶红外光谱和显微激光拉曼光谱的测试,结果显示,红外光谱均可见C—C的本征峰;绝大多数可见氮的吸收峰:双氮的吸收峰、聚合氮的吸收峰和氮片晶的吸收峰;部分可见氢的吸收峰:C—H的吸收峰、C—N的吸收峰和H2O的吸收峰.郯城金刚石以Ⅰa型金刚石为主,有ⅠaA、ⅠaB、ⅠaAB型,而Ⅱa型仅1粒;氮类型包括双氮(A心)、聚合氮(B心)及氮片晶(B'心),说明金刚石中的孤氮(C心)已经转化为双原子氮,但部分双原子氮未完成进一步的聚形.金刚石拉曼峰值集中在1131 cm–1,拉曼位移漂移程度较小,说明金刚石内部应力发生小幅的变化.在郯城金刚石中首次发现柯石英包裹体,出现139 cm–1、152 cm–1、212 cm–1、272 cm–1、328 cm–1、356 cm–1、428 cm–1和529 cm–1左右的拉曼峰值.在1粒金刚石中柯石英包裹体数量多达十余个,直径几μm至几十μm,呈针状、哑铃状、浑圆状和短柱状等多种形态.郯城金刚石中柯石英包裹体的出现,可作为郯城地区存在榴辉岩型金刚石的可靠标志,也佐证了该地部分金刚石的来源可能和洋壳循环或者俯冲过程有关.镁橄榄石包裹体上覆分散的黑色石墨斑点,与山东蒙阴、辽宁和湖南金刚石中的镁橄榄石等不同种类包裹体具有相似特征,推测这些石墨斑点是晶体包裹体形成后,由于外部环境温压条件的变化产生. 相似文献
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Fe-C(H)系高温高压金刚石多晶在合成片上呈成堆聚集状、不均匀分布.多晶中的金刚石晶粒多为八面体晶形、随机定向、大小无规律,表面发育"锯齿状"生长台阶,普遍发育塑性形变等缺陷.多晶中的金刚石晶粒间接触界线清晰、呈突变状.无论是利用品体成核、还是晶体长大理论都只能解释多晶中存在的部分现象.利用碳原子配位四面体生长基元模型分析多晶的形成机制值得探索.深入分析Fe-C(H)系高温高压合成金刚石多晶的形成机制不但有利于改善金刚石合成的工艺、提高合成金刚石多晶的品级.而且有利于为人们探讨天然金刚石多晶的形成机制及其深部意义提供科学线索. 相似文献
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从氧原子最紧密堆积以及阳离子充填四面体和八面体空隙原理出发 ,以简单氧化物矿物最紧密堆积结构类型金绿宝石、尖晶石、铁钒矿为基础 ,深入讨论了复杂氧化物矿物最紧密堆积结构类型彭志忠石、尼日利亚石、塔菲石、黑铝镁铁 (钛 )矿等晶体结构构筑原理。以O表示全部为阳离子八面体配位的层 ;以T层表示阳离子八面体配位与阳离子四面体配位的混合层 ,其中T1表示阳离子八面体配位与一种方向阳离子四面体配位的混合层 ,T2 表示阳离子八面体配位与两种方向阳离子四面体配位的混合层。这类矿物晶体结构可用O、T1、T2 堆积方式表征 ,O层与T层交替排列。如 :彭志忠石 ( 6H)的晶体结构表示为…OT2 OT1OT1… ,塔菲石 ( 8H)的晶体结构表示为…OT2 OT1OT2 OT1… ,尼日利亚石 ( 2 4R)的晶体结构表示为…OT1OT2 OT2 OT1…× 3 ,等等 ;它们的晶体结构中既有尖晶石的…OT2 OT2 …晶体结构单位 ,又有铁钒矿的…OT1OT1…晶体结构单位。 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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目前,在裂隙大的岩层和矿体中钻进时,采用T?-2型和T?H-4型的双管岩心钻具,配以59毫米或76毫米的金刚石钻头,岩心和矿心采取率应不低于70%.但是,采用这种钻具进行钻进,不是经常能够达到高指标,以致降低了工程质量.因此,为了能在极复杂的条件下进行钻进,试制了一种配备有正常胎体厚度的金刚石钻头的T?H-K1型岩心钻具(图1).T?H-K1型钻具可以在9~12级裂隙大或裂隙小的岩层和矿体中采取岩心和矿心.钻具是由外管 相似文献
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Geoffrey D. Bromiley Fabrizio Nestola Ming Zhang 《Geochimica et cosmochimica acta》2010,74(2):705-445
The solubility and incorporation mechanisms of water in synthetic and natural MgAl2O4 spinel have been investigated in a series of high-pressure/temperature annealing experiments. In contrast to most other nominally anhydrous minerals, natural spinel appears to be completely anhydrous. On the other hand, non-stoichiometric Al-rich synthetic (defect) spinel can accommodate several hundred ppm water in the form of structurally-incorporated hydrogen. Infrared (IR) spectra of hydrated defect spinel contain one main O-H stretching band at 3343-3352 cm−1 and a doublet consisting of two distinct O-H bands at 3505-3517 cm−1 and 3557-3566 cm−1. IR spectra and structural refinements based on single-crystal X-ray data are consistent with hydrogen incorporation in defect spinel onto both octahedral and tetrahedral O-O edges. Fine structure of O-H bands in IR spectra can be explained by partial coupling of interstitial hydrogen with cation vacancies, or by the effects of Mg-Al disorder on the tetrahedral site. The concentration of cation vacancies in defect spinel is a major control on hydrogen affinity. The commercial availability of large single crystals of defect spinel coupled with high water solubility and similarities in water incorporation mechanisms between hydrous defect spinel and hydrous ringwoodite (Mg2SiO4) suggests that synthetic defect spinel may be a useful low-pressure analogue material for investigating the causes and consequences of water incorporation in the lower part of Earth’s mantle transition zone. 相似文献
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绿柱石族宝石颜色丰富,一直是市场上重要的宝石品种。几十年来,国内外学者对不同颜色绿柱石的致色机理及改色工艺开展了广泛的研究。铁离子作为重要的致色过渡金属离子之一,其价态调控是绿柱石改色工艺的关键,所以铁离子的价态、晶格占位和对应的致色作用也一直是绿柱石研究的焦点。铁离子被认为可能存在于绿柱石中的铝氧八面体Al3+格位、硅氧四面体Si4+格位、铍氧四面体Be2+格位、结构通道2a或2b位和晶格间隙6g位等位置,是蓝、绿或黄等颜色绿柱石的主要致色元素。本文通过对绿柱石的晶体结构、铁离子的核外电子排布和晶格占位等方面文献资料的梳理及综合分析,认为Fe2+和Fe3+分别对蓝色和黄色绿柱石的呈色起着主导作用。当Fe2+和Fe3+处于晶格中不同位置时致色作用的具体差异,仍有待于进一步研究。 相似文献
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Analytical expressions are derived for the Poisson's ratios associated with a three-dimensional network of regular, corner-sharing
tetrahedra in which: (1) the tetrahedra are assumed to be rigid and free to rotate relative to each other; (2) the tetrahedra
are assumed to maintain shape and orientation but are free to change size (dilate); (3) tetrahedral rotation and dilation
are assumed to act concurrently. The structure has a primitive unit cell containing four tetrahedra and is analogous to the
molecular structure of α-cristobalite. Strain-dependent variations in Poisson's ratio are also predicted by the models. For
deformation due to tetrahedral rotation the network is found to exhibit negative Poisson's ratios in each of the three principal
directions, with the magnitude of the Poisson's ratio being dependent on the angle of rotation of the tetrahedra. The behaviour
of the Poisson's ratio is isotropic in the transverse plane, but anisotropic elsewhere. In the dilation model negative Poisson's
ratios equal to −1 are observed for uniaxial loading in any of the principal directions, with the value being constant irrespective
of tetrahedral size. The model for concurrent tetrahedral rotation and dilation allows positive as well as negative Poisson's
ratios, with the values determined by the framework geometry and relative strengths of the two mechanisms. The concurrent
model also offers a design route to materials and structures having ultrahigh Young's moduli.
Received: 15 February 2000 / Accepted: 1 October 2000 相似文献
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The molecular orbital and crystal field theories are compared and their applicabilities to bonding in silicates are discussed, A molecular orbital bonding model is favoured for orthopyroxene since bonding in both tetrahedral and non-tetrahedral sites within the crystal structure can be described and accommodated by the theory. It is suggested that Fe located in M2 sites has more electron delocalisation (or covalence) associated with it than Fe located in the M1 site. Order-disorder phenomena in orthopyroxene are discussed in relationship to Mueller's (1970) two-step exchange mechanism, whereby the first step corresponds to vacancy activation and the second step to exchange of Fe between an ‘octahedral’ site and a vacancy. 相似文献
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The effect of the Si/Al distribution in the tetrahedral sheets of the vermiculite mineral has been investigated employing density functional theory. The structures of six models for vermiculite with the structural formula (Mg4)(Mg12)(Si8Al8)O40(OH)8·24(H2O) per unit cell were fully optimized. The models differ by the T···Mg2+···T coordination of the interlayer Mg2+ cations by two central cations from the adjacent tetrahedral sheets of the 2:1 vermiculite layers (T,T=Si,Al). We observed the formation of very strong hydrogen bonds between water molecules solvating the interlayer Mg2+ cations and the surface basal oxygen atoms of the 2:1 layers. The directionality of hydrogen bonds is the major factor determining the layer stacking in the vermiculite structure. Results showed that the most stable model is that where only silicon atoms in the tetrahedral sheets coordinate all interlayer Mg2+ cations. 相似文献