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31.
采用常规宝石学仪器并结合电子探针、电子顺磁共振谱及紫外-可见光谱等测试方法,对软玉中不同深浅的黄玉与糖玉样品进行了系统分析,以探讨其致色原因及其差异。分析结果表明,黄玉的致色原因主要为O2-→Fe3+的电荷转移跃迁及Fe3+的6A1→4T2(D)跃迁,糖玉则主要由Fe3+的6A1→4E (D)、6A1→4T2(D)谱项跃迁与Mn3+的Jahn-Teller效应致色。黄玉中O2-→Fe3+的电荷转移跃迁导致可见光区的412~500 nm处吸收,是形成与控制黄玉颜色的重要因素;而糖玉因含有Mn3+致使黄绿色光被吸收而显示出黄绿色的补色。此外,Fe2+—Fe3+的荷移与Fe2+(5T2)+Fe3+(6A1)→Fe2+(5E)+Fe3+(6A1)跃迁也对糖玉和黄玉的致色具有贡献。 相似文献
32.
样品采自伊敏褐煤盆地中一个因次火山活动形成的烟煤区,包含了从褐煤到瘦煤的变质系列。红外光谱分析表明,煤的含氧基团在褐煤阶段已开始消失,烷基和芳环同步增加,在R°=1.10%时达最大值。顺磁共振自由基浓度和X-衍射参数La/Lc介于区域变质煤和岩浆接触热变质煤之间,芳核外官能团的热演化超前于芳核骨架及R°的演化。 相似文献
33.
构造煤和高温高压实验变形煤的EPR实验结果,充分显示了变形煤的EPR参数具有随Ro,max的增大而呈现规律性演化的特征,在Ro,max〉4%以后煤结构演化机理向拼叠作用的转化在实验变形煤和构造煤中也有很好的体现。但是,变形煤Ro,max的增大除与温度和围压条件有关外,还深刻地受到定向压力或构造应力的影响,尤其是对镜质组反射率各向异性的增强、煤大分子结构有序畴及定向性的增大更具有极为重要的控制作用。 相似文献
34.
Glass samples from alkali-trachytic pumice of the Lower Member (LM, level LM1) and Upper Member (UM) of the Neapolitan Yellow
Tuff at Campi Flegrei Caldera were studied by nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy.
The EPR data show that the relative occupancy of the different iron sites varies in samples from the Lower Member LM1 and
Upper Member of the eruptive sequence. The LM1 glasses are characterized by a more homogeneous distribution of the cationic
site population of iron compared with UM and by a different Fe3+/Al3+ substitution in the C2v symmetrical sites of the silicate framework. 29Si MAS NMR spectra on glasses indicate that LM1 glasses are more depolymerized than UM glasses, indicating the existence of
structurally distinct magma batches. 27Al MAS NMR spectra indicate the occurrence in UM glasses of aluminum in both tetrahedral and octahedral coordination; the
observed AlVI is believed to be a primary feature of the glass, since 27Al CP-MAS NMR experiments do not reveal detectable esa-hydrated Al. The Al in sixfold coordination could be ascribed either
to the more abundant alkali–OH terminations in UM, in which alkalies would be extracted from their charge-balance role for
Al, thus altering its fourfold structural position, or to permanent compaction during fast cooling and decompression of high-pressure
melts. 23Na CP-MAS NMR experiments indicate the existence of Na–OH groups in both LM1 and UM glasses, relatively more abundant in the
latter. Although preliminary, the results indicate the possible application of atomic-scale studies to variables that determine
the regimes of explosive volcanism.
Received: 1 July 1998 / Accepted: 1 October 1998 相似文献
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37.
Mohamed I. Moustafa 《Resource Geology》2010,60(3):300-312
The Egyptian black sands contain several economic minerals, such as ilmenite, magnetite, garnet, zircon, rutile and monazite. During the concentration and separation of a high-grade rutile concentrate a bulk magnetic fraction is obtained. This fraction is composed mainly of opaques, titanhematite, ilmenite–titanhematite exsolved intergrown grains, magnetic leucoxene in addition to chromite, and magnetic rutile. The magnetic rutile occupies 6 wt.% of the bulk magnetic fraction or approx. 4 wt.% of the original rutile content in the raw sands. Most of magnetic rutile crystals are contaminated with opaque inclusions, staining-coating and/or composite locked grains. This magnetic rutile has a magnetic range from strongly paramagnetic to very weak paramagnetic. Electron microprobe analysis for twenty-three magnetic rutile grains identified mineral components of rutile, titanhematite, pseudorutile, leached pseudorutile and ilmenite in decreasing order of abundance. Some other inclusions are also detected in the different magnetic rutile grains. They are most probably garnet, silica, amphibole, ilmenite, feldspar, mica and zircon. The presence of these inclusions reflect the derivation of magnetic rutile of various crystalline igneous and metamorphic rocks. The magnetic susceptibility of magnetic rutile depends on the associated mineral components and their relative volumes in comparison to the rutile mineral component. Magnetic susceptibility of magnetic rutile is also related to both type and size of the associated mineral inclusions. The average chemical composition of the magnetic rutile is 66.34 wt.% TiO2, 21.71 wt.% Fe2O3, 6.39 wt.% SiO2, 1.80 wt.% Al2O3, 1.19 wt.% CaO and 0.10 wt.% Cr2O3. Thus, the contamination of magnetic rutile in the non-magnetic rutile concentrate would decrease the market value of the rutile concentrate. Alternatively these magnetic rutile grains are recommended to be blended with magnetic leucoxene or some types of ilmenite concentrate to improve the overall marketable specifications especially for both of Ti, Fe and Cr contents. 相似文献
38.
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
39.
本文介绍了双向晶体旋转仪的原理及研究情况,以及应用它研究金刚石,红宝石处在非立方对称时的杂质氮和铬的实验结果。 相似文献
40.