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众所周知,金刚石按含氮量分成Ⅰ型和Ⅱ型。Ⅰ型含氮高,氮浓度大于0.01％;Ⅱ型一般不含氮,氮浓度小于0.001％。Ⅰ型中,含顺磁氮的称为Ⅰb型,其余为Ⅰa型。根据红外吸收光谱中7—10微米范围内各吸收峰的出现情况及强度差别,Ⅰa型又分为ⅠaA型和ⅠaB型。Ⅱ型中具有半导体性能的称为Ⅱb型,其余为Ⅱa型。1973年,S.托兰斯基(Tolansky)发表了采用紫外照相法在南非普雷米尔(Premier)等三个矿区中发现了混型金刚石的论文。所谓混型金刚石,指的是同一颗金刚石晶体 相似文献
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湖南砂矿金刚石包裹体原位测试:对金刚石成因来源的启示 总被引：2，自引：0，他引：2
包裹体是探究矿物结晶生长过程及其地球化学环境的重要探针,是反演寄主矿物形成机制及形成环境的有效工具。本文采用显微激光拉曼光谱、电子探针和LA-ICP-MS技术对来自湖南沅水流域的24颗宝石级金刚石的包裹体进行了原位分析。结果显示,湖南砂矿金刚石中橄榄岩型和榴辉岩型包裹体比例接近,橄榄岩型和榴辉岩型包裹体可在同一颗金刚石中"共存";湖南金刚石形成时地幔的温度和压力分别为1109~1237℃和4.05~5.83 GPa,相应的形成深度大致为133~192 km;包裹体成分及组合特征显示,扬子克拉通金刚石的形成环境与华北克拉通金刚石有显著差异,前者的形成与榴辉岩的关系更为密切,暗示有古老的地壳物质参与了金刚石的形成过程。 相似文献
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《西北地质》2020,(1)
大井头岩体为郯庐断裂带西侧首个发现的含金刚石钾镁煌斑岩。笔者对其中的金刚石进行了激光拉曼和傅里叶可变红外光谱研究。其激光拉曼和红外光谱特征研究表明,测试的6颗金刚石可分为1a型和Ⅰb型2类,部分Ⅰb型金刚石叠加有Ⅰa型金刚石所特有的1 175cm-1或1 182cm-1吸收谱峰。根据测试金刚石的外貌特征和Ⅰb型初生金刚石向1a型金刚石转换的机制,认为大井头钾镁煌斑岩中的金刚石并非岩浆结晶成因,而是金刚石于地幔中率先形成,其后被超深源岩浆携带至地表,应属地幔捕掳晶成因。结合大井头地区优越的构造地质条件、金刚石重砂矿物异常及多处钾质超基性岩、火山角砾岩体的出露,认为该地区有望成为鲁西地区第四金刚石原生矿带。 相似文献
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大别山及苏鲁地区微粒金刚石分类及其大地构造意义 总被引：3，自引：1，他引：3
1992年发现大别山首例微粒金刚石之后，又于2003年和2004年在大别山和苏鲁地区的榴辉岩薄片中和榴辉岩的人工重砂中发现了微粒金刚石。本文报道其中尚未发表的7颗，并对2颗较大的薄片中的微粒金刚石和2颗自由晶体金刚石进行拉曼光谱和红外光谱测试。研究结果表明，本区所有微粒金刚石都为IaA和IaB型金刚石的混合体。缺少Ib型金刚石，表明没有人造金刚石的混入。薄片中的金刚石大部分为石榴子石的包裹体，少数产出于颗粒之间，直径为30-180μm。自由颗粒微粒金刚石直径为400-700μm。在大别山北部，不但又一次找到了微粒金刚石，还在石榴子石中发现有单斜辉石、磷灰石和金红石的出溶。这表明北大剐不但是超高压地质体，而且可能是本区俯冲最深的地质体。 相似文献
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《吉林大学学报(地球科学版)》2015,(Z1)
<正>扬子克拉通西部(沅水流域)作为我国最重要的金刚石砂矿产地之一,倍受研究人员的高度关注。长期以来,由于与其母岩相关研究的不系统性及难度致使该地区金刚石的成因研究、找矿工作难于取得突破。近年来,研究人员注意到,金刚石多晶对于研究金刚石的结晶、生长环境、成因及其深部制约具有重要的指示意义。基于此,与扬子克拉通西部砂矿型金刚石多晶相关的研究开始受到重视。根据扬子克拉通西部砂矿型金刚石多晶的晶体形态特征,可将其划分为两种基本类型,即刻面状和浑 相似文献
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《吉林大学学报(地球科学版)》2015,(Z1)
天然金刚石形成于地球深部,反映丰富的地幔信息及演变历史[1-2]。金刚石中特征的氮原子缺陷是追溯其地幔存留时间和保存温度的重要依据[3-4],氮缺陷近年来也被认为是实现量子计算的优良载体,成为炙手可热的研究热点[5-6]。本世纪初新发现的储量巨大的津巴布韦砂矿型天然金刚石,引起了国内外学者的极大关注[7-10]。我们对已获得的津巴布韦金刚石样品进行预研究,注意到该产地金刚石具有特殊的立方体-八面体同时发育的镶嵌结构(下文简称mixed-habit),其氮和氢含量丰富,且氮和氢分别沿八面体生长区{111}和立方体生长区{100}具有择优取向特点。这种mixed-habit结构,不同于传统天然金刚石以八面体生长为主的结构[11],而与高温高压(HPHT)合成金刚石的结构较为相似[12],因而具有特殊的地质学背景和研究意义。我们将在下一阶段对这类金刚石在不同生长方向氮和氢缺陷存在形式及分布规律进行深入定量研究。重点通过电子顺磁共振光谱(EPR)对于不同氮缺陷如孤氮、双氮等的浓度比、占位形式和晶格畸变程度、自旋状态等进行表征,弥补传统红外光谱对于氮缺陷表征的不足。利用密度泛函理论(DFT)模拟不同氮缺陷的形成能解释实验观测的氮缺陷择优取向分布规律。根据对氮缺陷的聚集状态推算对应地幔存留时间和保存温度,追溯其形成过程和演变历史。 相似文献
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Mathieu Duttine Gérard Villeneuve Françoise Bechtel Gérard Demazeau 《Comptes Rendus Geoscience》2002,334(13):949-955
Natural quartz crystals coming from Madagascar, Angola, Brazil, and Spain were studied by EPR after β irradiation in order to characterise the paramagnetic centres due to impurities, and examine in which way their relative proportion could constitute a useful criterion for origin researches. In all our samples, EPR experiments revealed germanium centres [GeO4/M+]° with M = Li or Na, aluminium ones [AlO4/h]° and two titanium centres ([TiO4/H+]° and [TiO4/M+]°) also appeared, except for samples coming from Spain. The comparison of the relative concentrations of paramagnetic species led us on to draw diagrams that allowed distinguishing the origins of the studied samples using only EPR spectra. To cite this article: M. Duttine et al., C. R. Geoscience 334 (2002) 949–955. 相似文献
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Application of electron paramagnetic resonance spectroscopy to examination of carbonized coal blends
B. Pilawa S. Pusz M. Krzesi&#x;ska A. Koszorek B. Kwieci&#x;ska 《International Journal of Coal Geology》2009,77(3-4):372-376
Paramagnetic centers in two- and three-component coal blends carbonized at 1000 °C were studied by X-band (9.3 GHz) electron paramagnetic resonance (EPR) technique. The blends were prepared from three different Polish coals with carbon contents [wt.%]: 88.66, 86.21, and 82.67, respectively. The aim of this work was to compare EPR parameters and concentrations of paramagnetic centers in the initial and carbonized coal samples. Furthermore the spin–spin and spin–lattice interactions were characterized.EPR spectra were measured with magnetic modulation 100 kHz and microwave power 0.7 mW. Amplitudes and linewidths of EPR spectra were obtained. g-Factors were calculated from resonance condition. Concentrations of paramagnetic centers in the samples were determined. Influence of microwave power in the range 0.7–70 mW on EPR spectra was analyzed.All the studied samples revealed paramagnetism. Unpaired electrons are localized in the same atoms, because similar g-values in the range 2.0035–2.0038 were obtained for all the original samples. The EPR parameters of coal blends were additive in comparison with the parent coals. EPR spectra strongly changed after carbonization of the coal samples. Narrower EPR lines were measured for the original coal samples than for carbonized ones. We detected lower concentrations of paramagnetic centers in carbonized three-component coal blends than in two-component carbonized blends. EPR lines of the studied carbonized blends were not saturated at the microwave power used, which suggests fast spin–lattice relaxation processes in the samples. EPR examination proved chemical interactions between coal constituents during carbonization of coal blends. 相似文献
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The radiation sensitivity, time stability and optical sensitivity of [Si45−] paramagnetic centers in natural zircon crystals, particularly those from the Late Neopleistocenic tuff of the Elbrus Volcano,
have been studied. Optical bleaching was shown to result in the recombination of [Si45−] centers, while the concentration of centers increases in the absence of light due to the internal radiation background.
The data obtained show the infeasibility of using [Si45−] centers in zircons as paleodosimeters in conventional dating methods using electron paramagnetic resonance (EPR) spectroscopy.
New specific techniques need to be developed for EPR dating of zircons. 相似文献
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R. M. Mineeva A. V. Speransky S. V. Titkov N. G. Zudin 《Physics and Chemistry of Minerals》2007,34(2):53-58
The EPR-study showed that natural purple diamonds from kimberlites of Eastern Siberia (Russia) contain well known P1, P2 (in
some samples), W7, and N2 centers. The EPR spectra of these centers were typical of plastically deformed diamond single crystals.
Besides, several intense additional spectra of di-nitrogen centers were observed in purple diamonds. The angular dependence
analysis of these spectra showed that they can be attributed to known M2 centers. Comparison of principal axis directions
observed for sites of the M2 center in purple diamond crystals with theoretically predicted directions in the twin crystal
revealed that these centers are allocated exclusively to the twinned lamellae. Unusual phenomenon of the ordered distribution
of paramagnetic centers in natural purple diamonds confirmed that the plastic deformation in natural diamonds can be induced
not only by the slip of dislocations but also by the mechanical twinning. 相似文献
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Lorena N. Dias Maurício V. B. Pinheiro Klaus Krambrock 《Physics and Chemistry of Minerals》2009,36(9):519-525
Irradiation techniques are often applied to gem minerals for color enhancement purposes. Natural green, blue and colorless
specimens of rare gemological quality euclase, BeAlSiO4(OH), from Brazil were irradiated with gamma rays in the dose range from 10 to 500 kGy. Although the colors of the different
specimens were not strongly influenced, two different irradiation-induced paramagnetic defect centers were found by electron
paramagnetic resonance (EPR). The first one is an O− hole center interacting with one Al neighbor and the second is a Ti3+ electron center. The EPR angular rotation patterns of both irradiation-induced defects were measured and analyzed. The results
suggest that O− hole centers are formed by dissociation of the hydroxyl ions, similar as in topaz crystals. In euclase the OH− ions interconnect distorted Al octahedra and Be tetrahedra in O5 positions. During irradiation, the electrons are captured by titanium ions (Ti4+ + e−), leading to the formation of paramagnetic Ti3+ ions. From the EPR rotation patterns it is clear that these ions substitute for Al ions. The spin Hamiltonian parameters
of the irradiation-induced defects are analyzed and compared to similar defect centers in other mineral specimens. Thermal
annealing experiments show that the O− hole centers and Ti3+ electron centers are directly connected through the radiation process. 相似文献
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V. P. Solntsev R. I. Mashkovtsev A. V. Davydov E. G. Tsvetkov 《Physics and Chemistry of Minerals》2008,35(6):311-320
It is shown the possibility to determine the coordination of paramagnetic ions in disordered solid structures, e.g., in barium
borate glasses. For this purpose the electron paramagnetic resonance (EPR) method was used to study α-and β-BaB2O4 crystals and glasses of 45·BaO × 55·B2O3 and 40·BaO × 60·B2O3 (mol%) composition activated by Ag+ and Pb2+ ions. After the samples were exposed to X-rays at 77 K, different EPR centers were observed in them. In α-and β-BaB2O4 crystals and glasses the EPR centers Ag2+, Ag0, Pb+, Pb3+, and hole centers of O− type were studied. The EPR parameters of these centers and their arrangement in crystal structure were determined. It is
shown that Pb3+ ions in β-BaB2O4 crystals occupy Ba2+ position in an irregular polyhedron from the eight oxygen, whereas in α-BaB2O4 crystals they occupy Bа2 position in a sixfold coordination. Pb+ ions in α-BaB2O4 crystals occupy Bа1 position in a ninefold coordination from oxygen. In barium borate glasses, Pb3+ ions were studied in coordination polyhedron from six oxygen atoms and in a polyhedron from nine to ten oxygen atoms. It
is assumed that the established difference in the structural position of Pb3+ ions in glasses is due to their previous incorporation in associative cation–anion complexes (AC) and “free” structure-forming
cations (FC). Computer simulations have been performed to analyze the stability of specific associative complexes and to compare
their bond lengths with experimental data. 相似文献
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Crystals of the olivine minerals, tephroite (Mn2SiO4) and fayalite (Fe2SiO4) containing manganese(II) and iron (II and trace of III), respectively, were synthesized. Glasses were prepared from these crystalline materials by a splat-quench technique. Measurement of electron paramagnetic resonance (EPR) of all these powdered samples at room temperature show that the g-factors of Mn2+ in both glassy and crystalline environments (geff = 2.004) are the same, although the EPR linewidths (for glass, ΔHpp = 200 G; for crystals ΔHpp = 287 G) suggest less clustering of paramagnetic Mn2+ ions in the glass. Mn2+ probably occupies a distorted octahedral site in the tephroite crystal structure, although a four-fold coordination is suggested from other spectroscopic investigation on this glass. The EPR parameters of Fe3+ in synthetic fayalite glass (geff = 2.01 and 6.00; ΔHpp=150 and 1375 G, respectively, for the high and low field resonances) and powdered crystals (geff = 3.31 and ΔHpp = 900 G) indicated that Fe3+ ion in the crystals, is probably located in a distorted tetragonal site M2 and an axial environment has been proposed in the glassy system. 相似文献
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This article outlines the present state of knowledge of paramagnetic defects in crystalline zircon as obtained mainly, but not exclusively, from electron paramagnetic resonance (EPR) studies in crystalline zircon (zirconium silicate, ZrSiO4). The emphasis is on single-crystal studies where, in principle, unambiguous analysis is possible. Firstly, the crystallography of zircon is presented. Secondly, the relationships between available crystal-site symmetries and the symmetries of observed paramagnetic species in zircon, and how these observations lead to unambiguous assignments of point-group symmetries for particular paramagnetic species are detailed. Next, spin-Hamiltonian (SH) analysis is discussed with emphasis on the symmetry relationships that necessarily exist amongst the Laue classes of the crystal sites in zircon, the paramagnetic species occupying those sites and the SH itself. The final sections of the article then survey the results of EPR studies on zircon over the period 1960–2002. 相似文献
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INTRODUCTION Point defects in quartz have attracted intensiveand continuing research since the 1950s ( Weil ,2000 ,1984 ; Marfunin, 1979 ; Weeks , 1956 ; McClellandand Donoghue ,1953) because they are key factors inenhancing ( or reducing) device performance andquality of this i mportant piezoelectric and optical ma-terial (Beall ,1994) .Point defects in quartz are usu-ally dilute in concentration and,therefore ,are ame-nable to study by only a fewstructural techniques ,ofwhich electron… 相似文献