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1.
Gilalite is a copper silicate mineral with a general formula of Cu5Si6O17 · 7H2O. The mineral is often found in association with another copper silicate mineral, apachite, Cu9Si10O29 · 11H2O. Raman and infrared spectroscopy have been used to characterize the molecular structure of gilalite. The structure of the mineral shows disorder, which is reflected in the difficulty of obtaining quality Raman spectra. Raman spectroscopy clearly shows the absence of OH units in the gilalite structure. Intense Raman bands are observed at 1066, 1083, and 1160 cm?1. The Raman band at 853 cm?1 is assigned to the –SiO3 symmetrical stretching vibration and the low-intensity Raman bands at 914, 953, and 964 cm?1 may be ascribed to the antisymmetric SiO stretching vibrations. An intense Raman band at 673 cm?1 with a shoulder at 663 cm?1 is assigned to the ν4 Si-O-Si bending modes. Raman spectroscopy complemented with infrared spectroscopy enabled a better understanding of the molecular structure of gilalite. 相似文献
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The mineral lamprophyllite is fundamentally a silicate based upon tetrahedral siloxane units with extensive substitution in the formula. Lamprophyllite is a complex group of sorosilicates with general chemical formula given as A2B4C2Si2O7(X)4, where the site A can be occupied by strontium, barium, sodium, and potassium; the B site is occupied by sodium, titanium, iron, manganese, magnesium, and calcium. The site C is mainly occupied by titanium or ferric iron and X includes the anions fluoride, hydroxyl, and oxide. Chemical composition shows a homogeneous phase, composed of Si, Na, Ti, and Fe. This complexity of formula is reflected in the complexity of both the Raman and infrared spectra. The Raman spectrum is characterized by intense bands at 918 and 940 cm?1. Other intense Raman bands are found at 576, 671, and 707 cm?1. These bands are assigned to the stretching and bending modes of the tetrahedral siloxane units. 相似文献
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Nicolas Trcera Stphanie Rossano Martine Tarrida 《Journal of Raman spectroscopy : JRS》2011,42(4):765-772
The presence of magnesium in glasses of geological, medical, and technological interests influences their physicochemical and durability properties. However, the understanding of the role of magnesium is dependent on the combined knowledge of the structural environment of magnesium in the glass or melt and of the silicate network connectivity of the studied systems. In this article, we present a Raman spectroscopic study of the network connectivity of 10 ternary silicate glasses in the system Na2O MgO SiO2 and one Mg‐free binary silicate glass Na2O SiO2. Results obtained at constant polymerization suggest the existence of various Qn units according to the nature of the modifying cation. As polymerization decreases for Na2O MgO αSiO2 glasses (labeled as NMSα with α decreasing from 10 to 2), the band associated with Si O Si bending in fully polymerized region disappears being gradually replaced by a band attributed to Si O Si bending in region containing mainly Q2 and Q3 species. For highly polymerized glasses (NMS10‐NMS4), the coexistence of these two bands suggests the presence of two interconnected networks. Concomitantly, the signal associated with Q3 species first increases. For a further decrease of the polymerization, the high wavenumber part of the signal associated with Q3 species decreases, while the intensity of the high wavenumber part of the band related to Q2 species increases. This result strongly suggests that magnesium charge‐balances preferentially Q2 species rather than Q3 species. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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采用自主搭建的多光谱成像系统、便携式X射线荧光光谱仪(X-ray fluorescence spectrometer, XRF)、激光拉曼光谱仪(laser Raman spectrometer, LRS)对5件战国时期多色硅酸盐制品的表面物质的光谱特性、化学成分和物相结构进行了无损分析。根据多光谱图像中的光谱响应情况,对样品表面物质进行了区域划分,并发现样品表面的多数蓝、绿、紫色系区域出现荧光现象。XRF检测结果表明不同区域的化学成分存在明显差异,但多数区域均以SiO2,PbO,BaO为主要化学成分,5件样品基本属于铅钡硅酸盐体系,而且出现荧光区域皆是铜离子致色。LRS精确检测出各个区域中的玻璃相、中国蓝、中国紫、石英、赤铁矿、铅白、无定形碳等物相,并发现产生可见发光二极管致近红外荧光的物质为中国蓝和中国紫。利用X射线衍射技术(X-ray diffraction, XRD)验证了LRS检测结果的正确性。本研究将多用于书画分析的多光谱成像面检测技术与常用于硅酸盐文物成分分析的XRF和LRS技术进行有效结合,提出了一套更为高效的无损的分析古代多色硅酸盐制品的研究方法。光谱图像与X射线荧光光谱、激光拉曼光谱数据的结合,将样品的光谱特性与化学构成联系起来,有助于提高硅酸盐文物的分析效率,加强对硅酸盐文物的整体认识,和降低硅酸盐文物的受损风险。 相似文献
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Wim J. Malfait 《Journal of Raman spectroscopy : JRS》2009,40(12):1895-1901
The silicate speciation forms an important aspect of the structure of silicate melts, a subject of interest to both the earth‐ and materials science communities. In this study, the Qn speciation of binary cesium silicate glasses was studied by Raman spectroscopy. A method to extract the equilibrium constant from a set of Raman spectra is presented, and the least‐squares optimization algorithm is given (in Supporting Information). Log(K), the equilibrium constant of the speciation reaction, 2Q3 = Q4 + Q2, equals −2.72 ± 0.11 at the glass transition. This extends the previously established correlation between log(K) and the inverse of the ionic radius of the network modifier to cesium. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Silicon-29 NMR spectroscopy was used to characterize aqueous and alcoholic alkaline solutions of tri-butylmethyl ammonium (TBMA) silicates. The effect of TBMA cation on the equilibrium of silicate oligomers in aqueous alkaline silicate solutions was investigated using 29Si NMR spectra. It was found that TBMA cation has a structure directing role and directs the silicate species to form minor amounts of silicate anion in the presence of high concentration of silicon. Silicon-29 NMR spectra of TBMA silicate solutions indicate that considerable changes occurred by changing the Si/TBMA ratio. The distribution of silicate species was affected by the presence of the alcohols, specifically methanol. 相似文献
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We have used vibrational spectroscopy to study the formula and molecular structure of the mineral penkvilksite Na 2TiSi 4O 11·2H 2O. Penkvilksite is a mineral which may be used in the uptake of radioactive elements. Both Raman and infrared spectroscopies identify a band at ～3638 cm?1 attributed to an OH-stretching vibration of hydroxyl units. The inference is that OH units are involved in the structure of penkvilksite. The formula may be well written as Na 2TiSi 4O 10(OH)2·H 2O. The mineral is characterised by a very intense Raman band at 1085 cm?1 and a broad infrared band at 1080 cm?1 assigned to SiO-stretching vibrations. Raman bands at 620, 667 and 711 cm?1 are attributed to SiO and TiO chain bonds. Water-stretching vibrations are observed as Raman bands at 3197, 3265, 3425 and 3565 cm?1. Vibrational spectroscopy enables aspects of the molecular structure of the mineral penkvilksite to be ascertained. Penkvilksite is a mineral which can incorporate actinides and lanthanides from radioactive waste. 相似文献
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结合实际晶体的生长条件,探讨了不同温度、不同过饱和度下的甲酸钠和甲酸锂水溶液的Raman光谱,对谱峰进行认定和Gaussian多峰值拟合。分析温度、浓度、过饱和度及阳离子效应对溶液结构的影响,并比较分析甲酸锂溶液结构和一水甲酸锂晶体结构的差异。结果表明：在实验的条件下, 浓度、温度、过饱和度对溶液结构影响微小;阳离子对谱峰位置影响显著。 相似文献
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The mixed anion mineral dixenite has been studied by Raman spectroscopy, complemented with infrared spectroscopy. The Raman spectrum of dixenite shows bands at 839 and 813 cm−1 assigned to the (AsO3)3− symmetric and antisymmetric stretching modes. The most intense Raman band of dixenite is the band at 526 cm−1 and is assigned to the ν2 AsO33− bending mode. DFT calculations enabled the calculation of the position of AsO22− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1, and the deformation mode at 449 cm−1. The Raman bands at 1026 and 1057 cm−1 are assigned to the SiO42− symmetric stretching vibrations and those at 1349 and 1386 cm−1 to the SiO42− antisymmetric stretching vibrations. Both Raman and infrared spectra indicate the presence of water in the structure of dixenite. This brings into question the commonly accepted formula of dixenite as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6. The formula may be better written as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6·xH2O. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Ray L. Frost B. Jagannadha Reddy Marilla J. Dickfos 《Journal of Raman spectroscopy : JRS》2008,39(7):909-913
The molecular structure of the mineral pecoraite, the nickel analogue of chrysotile of formula Ni3Si2O5(OH)4, was analysed by a combination of Raman and infrared spectroscopies. A comparison is made with the spectra of the minerals nepouite and chrysotile and a synthetic pecoraite. Pecoraite is characterised by OH stretching vibrations at 3645 and 3683 cm−1 attributed to the inner and inner surface hydroxyl stretching vibrations. Intense infrared bands at around 3288 and 3425 cm−1 are assigned to the stretching vibrations of water strongly hydrogen‐bonded to the surface of the pecoraite. The asbestos‐like mineral is characterised by SiO stretching vibrations at 979, 1075, 1128 and 1384 cm−1, OSiO chain vibrations at 616 and 761 cm−1 and Ni O(H) vibrations at 397 and 451 cm−1. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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L. D. Kock 《Journal of Raman spectroscopy : JRS》2013,44(1):97-101
Raman microscopy is used in the analysis of glaze on a number of samples that include blue and white ceramic shards, a tile from the Citadel of Algiers and intact Ming plates. The use of the glaze depth profiling method for the study of interfacial pigments on these samples [J. Raman Spectrosc. 2007; 38: 1480] prompted the study of the glaze on the same set of samples to determine glaze type dependence of this method. Using the index of polymerization (Ip) which is closely correlated with glaze composition and processing temperature, it is shown that processing temperature could be estimated from a low of about 600 °C for some of the unknown archaeological shards to about 1000 °C or above for the Ming porcelain shards. Two intact porcelain plates from the Hongzhi (1488 – 1505) and Wanli (1573 – 1620) Ming imperial periods from the J. A. van Tilburg Museum of the University of Pretoria have been studied, and glaze/glass transition temperature was estimated to be above 1000 °C, consistent with historical data. A SnO2‐based glaze tile shard from the Citadel of Algiers was also successfully probed, and results indicated a much lower sintering temperature. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Sergei V. Goryainov Alexander S. Krylov Yuanming Pan Iliya A. Madyukov Mikhail B. Smirnov Alexander N. Vtyurin 《Journal of Raman spectroscopy : JRS》2012,43(3):439-447
Layer silicates F‐ and OH‐apophyllites, KCa4Si8O20(F, OH)·8H2O, have been investigated by Raman spectroscopy at hydrostatic and nonhydrostatic pressures up to ~8 GPa in diamond anvil cells using a 4 : 1 methanol–ethanol mix as pressure‐transmitting medium. Our experiments show that at hydrostatic compression, apophyllites retain their crystalline states (i.e. no amorphization) up to 5 GPa. The wavenumbers of most bands exhibit linear dependences on pressure, except for a few ones, e.g. at 162 and 3565 cm–1 in OH‐form (160.5 and 3558 cm–1 in F‐form) that show nonlinear dependences. Nonhydrostatic compression with additional uniaxial loading induces amorphization of apophyllites. The majority of the bands in OH‐apophyllite decreases markedly in intensity and shows considerable broadening under nonhydrostatic compression up to 3–6 GPa. In addition, the wavenumbers of several bands at nonhydrostatic compression exhibit considerable nonlinear dependences on pressure with strong hysteresis. These bands are mainly associated with vibrations of the interlayer ions and molecules and also of stretching and bending silicate sheets, hence being highly sensitive to the interlayer distance. Finally, we have calculated the lattice dynamics of F‐apophyllite and interpreted the majority of bands, and these data are used to explain the complex baric behavior of the bands. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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偏硼酸锂固体及其熔体结构的高温Raman光谱研究 总被引：2，自引：0，他引：2
本文对偏硼酸锂（ＬｉＢＯ２）从室温到１６７３Ｋ进行了Ｒａｍａｎ光谱测试,得到了其在不同温度下的Ｒａｍａｎ谱图。通过分析,阐述了常温下的链状ＢＯ３三角形结构在熔化后逐渐转变为六角环（Ｂ３Ｏ６）＾３－,即相变过程;以及在１２７３Ｋ后,由长链和六角环结构转化为ＣＲＮ（Ｃｏｎｔｉｎｕｏｕｓ Ｒｕｌｅｌｅｓｓ Ｎｅｔｗｏｒｋ,ＢＯ３单元组成的连续无规网络）的新的相平衡移动过程。通过各谱峰在相平衡移动过程中相 相似文献
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AbstractA molten mixture of sodium nitrate–sodium nitrite is an important heat transfer and storage medium. It is important to research the thermal stability of such melts. In the present study, the equilibrium between nitrate and nitrite ion in sodium nitrate–sodium nitrite melts under air atmosphere was studied by Raman spectroscopy and the thermal stability of the melts was analyzed. The results show that when the temperature was greater than 644?K, for melts in which the weighted-in content of sodium nitrate is 90 mass %, the content of nitrate ion decreased slightly with temperature. However, for melts in which the weighted-in content of sodium nitrate was 10–80 mass %, the content of nitrate ion increased with temperature. Melts in which the weighted-in fraction of sodium nitrite were 15.22%, 14.71%, and 14.60% under air atmosphere showed optimal thermal stability at 644?K, 762?K, and 880?K, respectively. The findings of this study have provided a foundation for optimizing the composition of molten salts and for providing molten mixtures applicable to important industrial processes. 相似文献
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Indranil Bhaumik Shailendra Kumar R. Bhatt B.N. Raja Sekhar 《Solid State Communications》2011,151(24):1869-1872
Large dispersion in the peak position of the OH− stretching mode (∼687.9 and ∼2167.7 cm−1/eV for fundamental and 3rd harmonic, respectively) is observed by Resonance Raman studies in congruent lithium tantalate single crystal under varying excitation energies. This is explained by considering the involvement of multiple LO phonons in the interaction with OH− stretching vibration and the resonantly excited electrons. The intensity of the peaks is also found to vary with the excitation energy. FWHM increases with the increase in excitation energy because of individual contributions of the increasing number of resonance steps to the broadening. 相似文献
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Aleksei M. Zheltikov 《Journal of Raman spectroscopy : JRS》2022,53(6):1094-1101
As one of the milestones in early-era nonlinear Raman studies, Akhmanov et al. [Sov. Phys. JETP 47 , 667 (1978)] and Koroteev et al. [Phys. Rev. Lett. 43 , 398 (1979)] have demonstrated that polarization coherent anti-Stokes Raman scattering (CARS) spectroscopy can resolve overlapping spectral lines that cannot be resolved by means of spontaneous Raman scattering spectroscopy and argued that the resolution of this method is unlimited. Here, we show that information theory offers useful insights into this remarkable result. We demonstrate that spectral super-resolution attainable in polarization CARS can be understood in terms of the Fisher information and the pertinent Cramér–Rao lower bound. We show that, with a suitable polarization arrangement, coherent Raman scattering can be tailored to yield super-resolving spectral modes that provide a nonvanishing Fisher information even for deeply sub-Rayleigh spectral features, preventing the variance of spectral measurements from diverging no matter how fine these spectral features are. When the nonresonant coherent background scattering can be efficiently suppressed, the Fisher information of such super-resolving modes reaches its upper bound as dictated by its quantum version—the quantum Fisher information. 相似文献