13 resultados para Apantallamiento EMI

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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The integrated absorption cross section Sigma(abs), I peak emission cross section sigma(cmi), Judd-Ofeld intensity parameters Omega(iota) ( t = 2,4,6), and spontaneous emission probability A(R) of Er3+ ions were determined for Erbium doped alkali and alkaline earth phosphate glasses. It is found the compositional dependence of sigma(emi) 5 almost similar to that of Sigma(abs), which is determined by the sum, of Omega(1) (3 Omega(2) + 10 Omega(4) + 21 Omega(6)). In addition, the compositional dependence of Omega(1) was studied in these glass systems. As a result, compared with. Omega(4) and Omega(6) the Omega(2) has a stronger compositional dependence on the ionic radius and content of modifers. The covalency of Er-O bonds in phosphate glass is weaker than that in silicate glass, germanate glass, aluminate glass, and tellurate glass, since Omega(6) of phosphate glass is relatively large. A(R) is affected by the covalency of the Er3+ ion sites and corresponds to the Omega(6) value.

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Compositional influences on the spectroscopic properties of Yb3+ and the structural variations with the introduction of YbF3 were studied in fluorophosphate glasses. Emission cross-section (sigma(emi)) and gain coefficient (sigma(emi) x tau(f)) were calculated which exhibit maximum at RF2 = 33 mol%. YbF3 has an important effect on the glass forming ability of fluorophosphate glasses when RF2 is over 36 mol%. The study of Raman spectra showed big differences on the glass structure between non-Yb3+ and Yb3+ -doped glasses. The main building units in Yb3+-doped samples are metaphosphate groups, pyrophosphate groups (P-2(O,F)(7), PO3F), Al[F-6] +Al[O,F](6) and F3Al-O-AlF3 while those of the non-Yb3+-doped glasses are monophosphate group P(O,F)(4), little pyrophosphate group, Al[F-4] + Al[F-6] + Al[O,F](4) + Al[O,F](6) and F3Al-O-AlF3, which means Yb3+ ions contribute to a better glass polymerization and network uniformity. (C) 2004 Elsevier B.V. All rights reserved.

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In a three-components fluorophosphate glass system, the introduction of H3BO3 brings some valuable influence to the spectroscopic and thermal properties of the glasses. With H3BO3 increases from 2 to 20mol%, ohm(6), S-ed4113/2, FWHM, T-g and fluorescence lifetime change from 3.21 x 10(-20) cm(2), 1.77 x 10(-20) cm(2), 45 nm, 480 degrees C and 8.8 ms to 4.66 x 10(-20) cm(2), 2.11 x 10(-20) cm(2), 50 nm, 541 degrees C and 7.4 ms, respectively. sigma(abs), sigma(emi), FWHM x tau(f) x sigma(emi) has a maximum when H-3 BO3 is 11 mol%. T-g and T-x-T-g increases with H3BO3 introduction. Results showed that in fluorophosphate glasses, proper amount of B2O3 can be used as a modifier to suppress upconversion and improve spectroscopic properties, broadband property and crystallization stability of the glasses while keeps the fluorescence lifetime relatively high. (c) 2005 Elsevier B.V. All rights reserved.

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The spectral properties in different concentration of Yb ions (0.5-5 mol%)-doped silica glasses are explored in this paper. The glasses are prepared by traditional melting method. The absorption spectra and the fluorescent lifetime (tau(f)) are measured at room temperature and low temperature (18 K). The stimulated cross-section (sigma(emi)) and potential laser properties (beta(min), I-sat, I-min) are calculated based on the absorption spectra. The absorption cross-section (sigma(abs)) are in the range 1.08 x 10(-20) - 1.18 x 10(-20) cm(2) in different glasses, the fluorescence lifetime (tau(f)) change from 1.9 to 1.2 ms with the increase of Yb3+ concentration. The potential laser properties indicate that lead silica glass is a good host for highly Yb ion doping glass. (c) 2005 Elsevier B.V. All rights reserved.

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A novel microwave packaging technique for 10Gb/s electro-absorption modulator integrated with distributed feedback laser (EML) is presented. The packaging parasitics and intrinsic parasitics are both well considered, and the packaging circuit was synthetically designed to compensate for the intrinsic parasitic of the chip. A butterfly-packaged EMI module has been successfully developed to prove that. The small-signal modulation bandwidth of the butterfly-packaged module is about 10 GHz. Optical fiber transmission experiments have shown that the module can be used for 10Gb/s optical transmission system. After transmission through 40km,. the power penalty is less than 1 dBm at a bit-error-rate of 10-12.

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采用传统的高温熔融工艺制备了铒镱共掺铅硅酸盐玻璃. 测量了样品的吸收光谱、荧光光谱和折射率, 利用McCumber 理论和Judd-Ofelt 理论计算了该玻璃系统中Er3+离子4I13/2→4I15/2 能级跃迁受激发射截面和荧 光寿命.该玻璃在1 536 nm 处受激发射截面σemi 为8.62×10-21 cm2;荧光寿命长达11.32 ms(实验测量值为9.26 ms);在1536 nm 附近有很强的荧光发射,荧光有效线宽为46.5 nm;样品存在中心波长为580 nm 的4S3/2→4I15/2 跃迁的上转换荧光. 结果表明,该样品荧光寿命长,受激发射截面大,同时具有较弱的上转换发光等特性, 是制作高能脉冲光纤激光器的理想材料

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Bayan Obo REE-Nb-Fe ore deposit is the largest REE deposit in the world. Owing to its unique type and tremendous economic value, this deposit has widely attracted interests from geological researchers and vast amount of scientific data have been accumulated. However, its genesis, especially ore-forming age and REE sources, have been under dispute for a long time. On the basis of previous research works, this paper mainly conducts studies on the Early Paleozoic ore-forming event in the Bayan Obo deposit. The following results and conclusions can be suggested: Sm-Nd isotopic analytical results of bastnaesite, beloeilite, albite and fluorite samples from a coarse-crystalline ore lode present an isochron age of 436±35Ma. Besides, Rb-Sr isotope dating of the coarse-crystalline biotite lode that intruded into banded ores gives an isochron age of 459±39Ma. The two ages verify the exist of Early Paleozoic ore-forming event at Bayan Obo, which characterized by extensive netted mineralization of REE fluorocarbonates, aeschynite and monazite, accompanied by widely fluorite-riebeckite-aegirine-apatite alteration. Sr-Nd isotope composition of vein minerals is located between EMI and ancient lower crust component in the ISr(t)-εNd(t) correlation diagram, indicating that there is a crustal contamination during veined mineralization. A large area late Paleozoic granitoids are distributed in the southeast region of east open pit of the mine. The granitoids intruded directly into the ore-bearing dolomite, and produced intense skarnization. Moreover, at 650-660m of the drill core on 22 line and 1598m level flat in the south of East Open Pit, we firstly found skarnization rocks. Single grain and low background Rb-Sr isochrone dating on phlogopite in skarn gives 309±12Ma. Considering the intruded contacting relationship, the late Paleozoic granitoids, already extended to the under part of REE ore bodies, must be posterior to the latest intense REE mineralization, and is only a destructive tectonic and magmatic activity. Fluid inclusion types of fluorite in the Bayan Obo deposit consist of multiphase daughter mineral-bearing inclusion, two or three phase CO2-bearing inclusion and two phase aqueous inclusion. Petrography, laser Raman analysis and microthermometry study indicate that the fluids involving in REE-Nb-Fe mineralization at Bayan Obo might be mainly of H2O-CO2-NaCl-(F-REE) system. The presence of REE-carbonate as a daughter mineral in fluid inclusions shows that the original ore-forming fluids are rich in REE elements.

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The Tiezhai intrusive complex is located in the north of the Luxi block, Shandong province, eastern China. It lies ~30 km west of the Tanlu fault, and is at the cross of the Wujing and Jiushan faults. The Tiezhai complex was formed about 120~130 Ma, when large-scale magmatism was active in eastern part of North China. This paper carries out petrochemical and geochemical study on the Tiezhai intrusive complex, and discusses its genesis in detail. The Tiezhai intrusive complex can be subdivided into three rock series. The first is the gabbro-diorite series formed in early stage. Its composition variation shows 01 and Cpx fractional crystallization trend. The second is the porphyritic diorite and monzonite series, showing dominating Hb fractional differentiation. Their composition variation shows Hb fractional crystallization trend. The third is the porphyritic quartz monzonite with K-feldspar megacrysts, showing weakly Hb and Bi fractional crystallization trend. All types of rocks in the Tiezhai complex are belonging to the high-K cac-alkaline series. They have elevated Sr (450-1660 ppm), Ba (210-1780 ppm) and relatively low Rb (30-100 ppm). For the gabbro-dioritic rocks in the early stage, the abundances of Ni (20-250 ppm), Cr (50-350 ppm), V(l30-250 ppm) and Co (20-40 ppm) are high, indicating a mantle origin. All rocks have negative anormalies of Nb, Ta, Ti and P, and enriched LREE and strong differentiated REE patterns. The porphyritic monzonites and quartz monzonites have very low HREE, Yb and Y contents and positive Eu anormalies, similar to adakite. Most rocks have lowε_(Nd)(t) of-1.5~-10.9, and high (~(87)Sr/~(86)Sr)_i of 0.704~0.709. The data have characters of enriched lithosphere mantle (EMI). In summary, the Tiezhai intrusive complex was inferred to be generated by a mantle derived magma through fractional crystallization. When the primary magma gathered in some place between crust and mantle, the crystallization started and causing magma evolution. The remaining / evolved magma ascended and emplaced again and again in the upper crust in Tiezhai area. Then Tiezhai complex formed. The porphyritic monzonites and quartz monzonites have major and trace element characters of typical adakite, but they are likely to be generated by Hb fractional crystallization.

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峨眉山大火成岩省二滩地区玄武岩W(SiO2)/%=40.5~59.65;普遍高碱,w(K2O+Na2O):2.64%~7.67%。W(TiO2):2.10%~6.53%,Ti/Y〉500,该区玄武岩属于高钛(HT)型玄武岩;其Mg^#:58~84,明显高于高于宾川高钛玄武岩(31~53),说明岩浆演化程度明显低于宾川高钛玄武岩浆。岩石样品中Sr显示明显负异常,暗示了二滩玄武岩经历了广泛的斜长石结晶分离;而Eu不显异常,则反映了玄武岩岩浆中有高Eu^3+/Eu^2+比值的存在,其环境为氧化环境。在二滩玄武岩和宾川高钛玄武岩中,Ni,Zr,TiO2和Mg^#均显示了明显差异,说明二滩玄武岩具有独立的地球化学特征。二滩玄武岩不相容元素(Rb,Ba,Th,U,Nb,Ta,La,Ce等)配分曲线与OIB相似,及其Ta/Yb vs Th/Yb双变量图解也显示出了富集地幔特征,这些特征反映了峨眉山二滩玄武岩源区为富集地幔源,玄武岩岩浆可能为地幔柱物质。此外,Ba/Th,Zr/Nb,La/Nb,Ba/Nb等比值介于EMI OIB和EMII OIB之间,以及Ce/Pb比值也说明:二滩玄武岩缺少HIMU OIB端元组分,是EMI OIB和EMII OIB两端元的混合产物。

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对比研究了中国26个主要斑岩铜矿的地球化学特征和年代学,结果表明其中25个矿床与埃达克 (质)岩有成因联系,且多数与玄武质下地壳熔融形成的埃达克岩(C型)有关,现有数据表明土屋一延东和普朗斑岩铜矿可能与俯冲板片熔融形成的埃达克岩(o型)有关。容矿斑岩的初始锶值为O.703 4~0.709 O,均大于洋中脊玄武岩和亏损地幔的初始锶值,多数与EMI的初始锶饭接近,推测其源区或源岩主要为富武质下地壳,少数为洋中努玄武岩,舞受到中、上地党不同程度的混染,这与两类埃迭克岩的源区基本一致。强然埃迭克壤岩浆吴寄形成斑岩铜矽的巨走潜力,钽并菲所有埃迭克岩都能成矿,笨麓岩傣需葵体分新。

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基性岩脉具有特殊的地球动力学意义,一直是近十年来国际上研究的热点和重点。至今共举办过四次关于岩脉的国际专题大会,掀起了基性岩脉的研究高潮,分别从其分布、形态、古地磁、岩石学、地球化学、年代学和构造演化等方面进行了系统的研究。由于出露面积的关系,岩脉或岩脉群往往容易被人忽略,直到最近五年来中国东部中新生代基性岩脉的地球动力学意义才引起地质学者的关注,甚至有些学者指出中国东部中生代基性岩脉的研究可以填补国际上对此方面的空白。对中国东南部中生代基性岩脉的系统研究主要集中在粤北地区,琼南、福建沿海一带、湘东南、某些热液矿床的矿区的基性岩脉得到零星的研究,缺少对中国东南部更大范围的和系统的研究。另外,中国东南部晚中生代部分基性岩体与地壳拉张有关,但研究多集中于沿海一带,对于内陆基性岩体的构造应力体制是否与基性岩脉类似。本论文选择了江西省晚中生代以来的基性岩脉(体)为研究对象,运用矿物学、元素和同位素地球化学及K-Ar测年等研究方法,首次较为系统地研究了江西省晚中生代以来的基性岩脉、与地壳拉张有关的基性侵入岩体的地质地球化学特征,并利用对其形成时代、源区性质的研究来探讨中国东南部地壳拉张期次、地幔性质等地球动力学背景中的关键性问题。通过研究取得了以下几点初步认识:1系统地进行野外地质考察和采样,并收集前人的研究资料,发现江西省的基性岩脉的岩石类型主要为煌斑岩、辉-长辉绿岩、辉绿岩、辉绿(珍)岩等,相对较多,主要呈三条北北东向带状分布,分别为星子-上高-萍乡、德兴-余江-相山-吉安-上犹、草桃背-岩背-大吉山。2对江西省的基性岩脉和部分与地壳拉张有关的墓性岩体进行全岩K-Ar定年,结果表明,基性岩脉的形成时代为140-50Ma,再结合中国东南部发育的富碱侵入岩(包括A型花岗岩)和已发表的基性岩脉的年代学资料,作者认为中国东南部地壳拉张可能共有六期,分别为50-6OMa、90士Ma、100-11OMa、125士Ma、140士Ma、165~180 Ma。3对赣南车步辉长岩类的地质特征、矿物学和地球化学特征进行了研究,着重讨论它与沿海辉长岩类构造环境和源区性质的不同,研究表明它可能是中国东南部中侏罗世软流圈上涌、岩石圈伸展和地壳裂解的产物,而沿海白至纪辉长宕类的构造环境是弧后拉张盆地;车步辉味岩类的源区可能是未受到明显俯冲组分影响的富集地幔,而沿海白翌纪辉长岩类的源区可能包含较多俯冲组分。4对赣南大吉山地区和赣北地区早白圣世基性岩脉的地质地球化学特征进行了系统的研究,表明它们可能代表中国东南部早白至世初存在一次重要的岩石圈伸展和地壳拉张事件。但两者在岩石序列、微量元素、同位素方面存在明显不同,结合区域地质背景,认为造成赣南和赣北地区早白坐世的基性岩脉源区不同的可能原因是岩石圈地慢组成不同和/或形成基性岩脉的岩浆深度不同。5通过对江西省早白至世欧特里夫期(125士Ma)基性岩脉的地质、矿物学和地球化学特征进行研究,发现中国东南部的确存在早白至世欧特里夫期(125士Ma)基性岩脉,代表一次重要地壳拉张事件,其源区可能由亏损地幔、EMIEMII地幔组成,后面两种类型地幔可能是先前受俯冲流体影响的成分不均一的富集岩石圈地幔。6通过对江西省早白至世未期(100-11oMa)和晚白至世(90士Ma)的基性岩脉(体)的地质地球化学特征进行研究,强有力的表明江西省存在100-110Ma、90士Ma两期地壳拉张,与粤北地区类似。本论文研究表明晚白至世的地壳拉张除了形成基性岩脉外,还形成同时代的基性岩体。这两期的基性岩脉(体)的源区可能由亏损地幔、EMI和EMll地幔组分组成,与(125士Ma)基性岩脉类似,但早白至世未期(100-110Ma)基性岩脉的源区可能含有相对较高的亏损地幔组分。7通过对江西省中部古新世的基性岩脉(体)的地质地球化学特征进行研究,发现了江西省中部的确存在50-60Ma地壳拉张事件。本期的基性岩脉(体)微量元素含量、MORB标准化模式和同位素与前面白至纪的基性岩脉(体)明显不同,软流圈参与其源区明显增多。8通过对中侏罗世以来基性岩脉(体)地质地球化学的系统研究,表明中国东南部晚中生代以来地幔性质发生了明显变化,总体变化趋势为亏损地幔代替富集地幔,这种过程与软流圈上涌、岩石圈伸展和地壳拉张有关:主要机制可能为岩石圈减薄,当然不排除其他机制。

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四川耗牛坪稀土矿床是中国仅次于白云鄂博的第二大原生轻稀土矿床。矿区碳酸岩-正长岩与REE矿化时空上密切共生。本论文系统分析了矿区碳酸岩-正长岩的主要元素、微量元素、REE、PGE和C、O、Sr、Nd、Pb同位素组成,探讨了碳酸岩-正长岩的地慢源区特征及两类岩石的成因联系;结合矿区主要脉石矿物萤石和其它岩浆岩的REE、Sl-Nd-Pb同位素、流体包裹体地球化学,探讨了REE成矿流体的来源,初步建立了REE成矿模式。取得的主要认识有:1,系统研究了耗牛坪REE矿床碳酸岩-正长岩的地球化学特征,揭示了两者的地慢源区特征和成因联系。受陆内俯冲作用的影响,具有EMZ指纹的地壳物质俯冲交代具EMI特征的岩石圈地慢,形成碳酸岩一正长岩的初始地慢,该地慢经低程度部份熔融作用形成富COZ硅酸岩熔体—碳酸岩-正长岩原始岩浆,该熔体在演化过程中发生液态不混溶作用形成碳酸岩和正长岩。2.通过对耗牛坪REE矿床碳酸岩PGE地球化学的研究,发现碳酸岩具有携带PGE的能力,其PGE配分模式与西藏大竹卡方辉橄榄岩相似。初步认为本区碳酸岩中的PGE可能主要来源于俯冲或地鳗交代的流体,除硫化物外,合金或挥发份都可能影响碳酸岩PGE的配分模式。3.萤石是耗牛坪REE矿床重要的脉石矿物之一,其形成贯穿了整个成矿过程。根据REE地球化学参数将萤石分为LREE富集型、LREE平坦埠和LREE亏损型。三种REE类型的萤石具有相似的Sr、Nd、Pb同位素组成,为同源不同阶段的产物,形成顺序为LREE富集型-LREE平坦型-LREE亏损型。4.萤石的Sr、Nd、Pb同位素组成与矿区碳酸岩-正长岩相近,明显不同于花岗岩;早期萤石的REE地球化学特征也与碳酸岩-正长岩相似,与花岗岩、流纹岩和玄武岩存在差别;在萤石中发现了流体-熔融包裹体。这些特征均表明牡牛坪REE矿床成矿流体主要来源于碳酸岩-正长岩熔体,矿床为地幔流体成矿的产物。

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燕山期(205~65Ma)山东地区地壳活动强烈,构造体系已由古亚洲构造域完全转化为滨太平洋构造域,构造活动导源于太平洋板块对欧亚板块的俯冲。由于太平洋板块对欧亚板块的俯冲(NW向),鲁东地区岩石圈发生了快速拆沉减薄作用.同时鲁东地区也可能会出现地l漫柱的活动;另外,在太平洋板块俯冲作用影响下,炎区庐断裂(山东称沂沐断裂)带发生了大型左行走滑剪切和拉张活动。以上构造因素加上早白至世末一晚白至世期间燕山造山带的垮塌,都可能为山东地区中生代地壳拉张提供了动力条件。山东地区中生代(燕山期)基性脉岩特别发育,这些慢源基性岩脉充填张性裂隙,是大陆地壳拉张的标志;另外,山东地区也存在大量拉张背景下的燕山期火山岩和碱性岩。但关于它们的年代学和系统的地球化学研究还比较薄弱,且对其成因和形成的构造环境,仍存在着争议。本论文主要从同位素年代学、岩石化学、地球化学和Sr-Nd-Pb同位素方面对山东地区燕山期基性脉岩、火山岩和碱性超基性脉岩进行了系统研究。同时,考虑到鲁东地区煌斑岩中金含量普遍较高,且燕山期又是山东金矿的主成矿期,论文中对煌斑岩与金成矿之间的关系也作了一定的研究。通过研究,得出以下主要认识:1、火山岩为一套以钙碱性安山岩为主,含少量拉斑玄武岩和英安岩。成因上为富集地慢部分熔融作用的结果,但在成岩过程中也可能存在单斜辉石、斜长石、橄榄石和Ti-Fe氧化物等矿物的分离结晶作用。碱性超基性脉岩岩性上为单一的橄榄辉石岩,为富集地慢源低度(3.4%)部分熔融作用的产物,岩浆演化过程经历了以橄榄石为主的分馏作用。基性脉岩主要包括辉长岩、辉绿岩(主要分布在鲁西地区)和煌斑岩(以斜闪煌斑岩为主,同时含部分拉辉煌斑岩和角闪煌斑岩)(主要分布在鲁东地区),都为富集岩石圈地慢部分熔融的产物。三类岩石在侵位结晶过程都不存在明显的地壳混染。2、火山岩、碱性超基性脉岩和基性脉岩(除少数外)都形成于大陆板内拉张环境。3、富集地慢源区(EMI)的产生是俯冲并熔融的扬子下地壳物质进入华北岩石圈地慢并与之相互交代作用形成的。4、研究区中生代基性脉岩K-Ar年龄分布范围为72.2±1.70Ma~204.2±5.4Ma,且基本上在90~140Ma之间变化。综合碱性超基性脉岩和已知的青山组的火山岩、基性脉岩年龄数据,认为山东地区中生代地壳拉张至少存在四次:即约80Ma、100Ma、120Ma和 140Ma。但鲁东地区在地壳拉张方面可能存在着与鲁西地区不同的制约因素:即鲁东地区存在拆沉作用和可能存在地慢柱的影响,而鲁西地区可能受到了郊庐断裂的左行走滑剪切和拉张活动的影响。5、胶北地区煌斑岩为钙碱性系列,且金含量普遍较高(平均28ppb),该研究对胶北地区的找矿勘探工作具有一定意义。