共查询到19条相似文献,搜索用时 93 毫秒
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高温高压下电解质溶液谱学研究的进展 总被引:2,自引:0,他引:2
高温高压下电解质溶液研究在理论和工业应用上都具有重要的意义,拉曼光谱、红外光谱、紫外可见光谱、中子和X射线衍射、以及X射线吸收精细结构方法都已经用于它的研究。随着温度升高,溶液的结构发生了变化,离子的缔合度增加,内层配位水的数目减少,出现了离子的多核簇组成。除了静态结构的研究外,也用拉曼光谱进行溶液的动力学探讨。水热金刚石压腔装置是高温高压电解质溶液研究的一个重要的进步,在水热金刚石压腔装置中,拉曼光谱和X射线吸收精细结构两种方法具有重要的应用潜力。 相似文献
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高温高压下地球内部物质弹性波速的实验测量数据,可直接与地震波观测结果相结合,对地球内部的组成、状态和物质运移方式等进行反演,是了解地球深部信息的重要手段。在金刚石压砧(diamond anvil cell, DAC) 中利用布里渊散射对矿物波速进行原位测量,是人们研究地球各圈层弹性性质的重要方法。随着DAC实验技术发展,一方面,可以获得模拟地球各圈层的极高温压条件;另一方面,DAC的光学特性使得各种光学分析和测试方法得到了广泛的应用。要获得高温高压下的弹性波速,首先需要对样品腔中的实验压力和加热温度进行精确的标定和测量;其次需对散射信号进行处理,通过布里渊散射频移,求出样品中的波速;最后结合X射线技术获得的晶格常数,可由固体弹性理论解出矿物的各弹性参数。重点介绍了布里渊散射和拉曼散射等光谱学方法在弹性波速实验研究中的应用,阐述了它们在波速测量、压力和温度标定等方面的基本原理和研究进展。分析了两种光谱学定压方法(荧光光谱压标和拉曼光谱压标) 的定压方式和适用范围,以及两种主要的光谱学温标(黑体辐射温标和拉曼光谱温标) 在温度测量中的应用。最后,回顾了基于光谱学测量建立起来的布里渊散射系统对下地幔主要矿物(钙钛矿、方镁铁矿、斯石英等) 弹性波速测量取得的新成果,深入讨论了它们的地球物理意义,并对其未来的发展进行了展望。 相似文献
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本文在8 7GPa压力范围内研究了三聚氰胺(C3N6H6)的高压原位Raman光谱。通过内、外Raman活性模的压致效应,发现在1 5GPa和6 0GPa压力下该分子晶体发生了压致结构相变。用空间群相关原理确认在1 5GPa压力下它从单斜相转变为三斜相;在6 0GPa压力下又发生了另一次结构相变。然后在室温高压条件下对三聚氰胺进行了原位同步辐射能量散射x-ray衍射实验(EDXD),在14 7GPa压力范围内,观察到常压下为单斜晶系的三聚氰胺经历了两次压致结构相变。在1 3GPa下,三聚氰胺分子晶体从单斜相转变为三斜相;在8 2GPa又转变为正交相。本实验结果为利用三聚氰胺碳氮有机分子晶体高温高压合成超硬C3N4共价晶体的研究提供了重要信息。 相似文献
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对于天然镁铝石榴子石(Pyrope),在0~25.3 GPa压力条件下,在美国布鲁克海汶(Brookhaven)国家实验室国家同步辐射实验站,利用金刚石压腔装置(DAC),进行了角散X 射线粉末衍射的高压原位测量,获得了天然镁铝石榴子石随压力变化的衍射图谱。采用Materials Studio软件的Refinement模块对衍射图谱进行了分析,得到了镁铝石榴子石的晶胞参数及其随压力的变化,进而利用Birch-Murnaghan状态方程进行数值拟合,得到了镁铝石榴子石的零压体弹模量B0=199 GPa(B′0=4)。 相似文献
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利用金刚石对顶砧(DAC)装置产生高压,在室温下、0~32 GPa压力范围,对天青石(SrSO4)进行了原位高压X射线衍射和拉曼光谱研究. 根据高压X射线衍射的数据,测定了天青石的等温状态方程,得到天青石的零压体弹模量KT0=83GPa(K'T0=4), 在所研究压力范围内没有观察到相变的发生. 高压拉曼光谱的数据显示,在5GPa左右,SO4四面体弯曲振动峰发生劈裂,这是由SO4四面体畸变引起的;同时,所有的拉曼振动峰都随着压力的增加而增加, 并且,高频模的平均压力导数要高于低频模的,根据以上数据获得了模格林奈森参数. 相似文献
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《物理学报》2017,(3)
利用同步辐射光源开展高压X射线衍射(X-ray diffraction,XRD)研究已有近四十年的历史,并且已经取得了非常丰硕的成果.单晶XRD作为高压研究的一部分,在同步辐射装置上的应用也有了接近三十年的历史.近年来,随着同步辐射光学技术以及高压技术、特别是大衍射窗口金刚石对顶砧压腔(diamond anvil cell,DAC)的改进与发展,同步辐射高压单晶衍射实验方法在高压研究中的应用越来越普及.由于能够在压力条件下获得样品在三维空间中的衍射信息分布以及数据具有高信噪比等优势,单晶XRD实验方法不仅可以用于压力条件下的晶体结构解析,如获取晶胞参数、空间群、原子坐标以及原子占位等信息,而且可进一步做晶体电荷密度分析研究,得到更多的化学键、电荷分布及其变化等信息.本文主要介绍同步辐射高压单晶XRD实验方法及相关技术,其中包括单晶XRD实验系统、单晶XRD所用DAC、单晶样品装填以及单晶XRD数据处理等内容. 相似文献
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Dongliang Chen Juncai Dong Xiaoli Zhang Peiyu Quan Yaxiang Liang Tiandou Hu Jing Liu Xiang Wu Qian Zhang Yude Li 《Journal of synchrotron radiation》2013,20(2):243-248
In combination with a single‐crystal diamond anvil cell (DAC), a polycapillary half‐lens (PHL) re‐focusing optics has been used to perform high‐pressure extended X‐ray absorption fine‐structure measurements. It is found that a large divergent X‐ray beam induced by the PHL leads the Bragg glitches from single‐crystal diamond to be broadened significantly and the intensity of the glitches to be reduced strongly so that most of the DAC glitches are efficiently suppressed. The remaining glitches can be easily removed by rotating the DAC by a few degrees with respect to the X‐ray beam. Accurate X‐ray absorption fine‐structure (XAFS) spectra of polycrystalline Ge powder with a glitch‐free energy range from ?200 to 800 eV relative to the Ge absorption edge are obtained using this method at high pressures up to 23.7 GPa, demonstrating the capability of PHL optics in eliminating the DAC glitches for high‐pressure XAFS experiments. This approach brings new possibilities to perform XAFS measurements using a DAC up to ultrahigh pressures. 相似文献
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Fabio Furlan Ferreira Hamilton P. S. Corrêa Marcos T. D. Orlando José L. Passamai Jr Cíntia G. P. Orlando Isabela P. Cavalcante Flávio Garcia Edilson Tamura Luis G. Martinez Jesualdo L. Rossi Francisco C. L. De Melo 《Journal of synchrotron radiation》2009,16(1):48-56
The crystal and local atomic structure of monoclinic ReO2 (α‐ReO2) under hydrostatic pressure up to 1.2 GPa was investigated for the first time using both X‐ray absorption spectroscopy and high‐resolution synchrotron X‐ray powder diffraction and a home‐built B4C anvil pressure cell developed for this purpose. Extended X‐ray absorption fine‐structure (EXAFS) data analysis at pressures from ambient up to 1.2 GPa indicates that there are two distinct Re—Re distances and a distorted ReO6 octahedron in the α‐ReO2 structure. X‐ray diffraction analysis at ambient pressure revealed an unambiguous solution for the crystal structure of the α‐phase, demonstrating a modulation of the Re—Re distances. The relatively small portion of the diffraction pattern accessed in the pressure‐dependent measurements does not allow for a detailed study of the crystal structure of α‐ReO2 under pressure. Nonetheless, a shift and reduction in the (011) Bragg peak intensity between 0.4 and 1.2 GPa is observed, with correlation to a decrease in Re—Re distance modulation, as confirmed by EXAFS analysis in the same pressure range. This behavior reveals that α‐ReO2 is a possible inner pressure gauge for future experiments up to 1.2 GPa. 相似文献
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Pressure-induced structural changes in solid krypton (Kr) and xenon (Xe) have been studied using angle dispersive X-ray diffraction in a diamond-anvil cell (DAC) up to 50 GPa. The analysis of the results shows that in solid Kr (Xe) the phase transition from fcc to hcp starts below 3.2 GPa (1.5 GPa). Albeit the hcp/fcc ratio increases under pressure, both phases coexist up to the highest pressure reached in this study. Room temperature (RT) equations of state (EOS) are determined. 相似文献
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During the past decade, the radial x-ray diffraction method using a diamond anvil cell (DAC) has been developed at the X17C beamline of the National Synchrotron Light Source. The detailed experimental procedure used with energy dispersive x-ray diffraction is described. The advantages and limitations of using the energy dispersive method for DAC radial diffraction studies are also discussed. The results for FeO at 135?GPa and other radial diffraction experiments performed at X17C are discussed in this report. 相似文献
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Lili Gao Bin Chen Michael Lerche Esen E. Alp Wolfgang Sturhahn Jiyong Zhao Hasan Yava? Jie Li 《Journal of synchrotron radiation》2009,16(6):714-722
The applications of nuclear resonant scattering in laser‐heated diamond anvil cells have provided an important probe for the magnetic and vibrational properties of 57Fe‐bearing materials under high pressure and high temperature. Synchrotron X‐ray diffraction is one of the most powerful tools for studying phase stability and equation of state over a wide range of pressure and temperature conditions. Recently an experimental capability has been developed for simultaneous nuclear resonant scattering and X‐ray diffraction measurements using synchrotron radiation. Here the application of this method to determine the sound velocities of compressed Fe3C is shown. The X‐ray diffraction measurements allow detection of microscale impurities, phase transitions and chemical reactions upon compression or heating. They also provide information on sample pressure, grain size distribution and unit cell volume. By combining the Debye velocity extracted from the nuclear resonant inelastic X‐ray scattering measurements and the structure, density and elasticity data from the X‐ray diffraction measurements simultaneously obtained, more accurate sound velocity data can be derived. Our results on few‐crystal and powder samples indicate strong anisotropy in the sound velocities of Fe3C under ambient conditions. 相似文献
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E. Arakawa N. Ishimatsu N. Kawamura F. Itoh A. Ochiai H. Maruyama O. Shimomura 《Journal of Physics and Chemistry of Solids》2004,65(12):2089-2092
An experimental system for X-ray magnetic diffraction (XMD) under extreme conditions was constructed on the beamline BL39XU at SPring-8. This system aims at studying magnetic properties of ferromagnets through the measurements of magnetic form factors under the conditions of low temperature (5 K), high magnetic field (6 T) and high pressure (10 GPa). This system consists of a superconducting magnet (SCM), a diamond anvil cell (DAC), a two-axis manipulator for the DAC, a five-axis goniometer for the SCM, and an X-ray polarizer with a phase plate. Details of this system are presented. Experimental results on uranium telluride are shown as a performance test with this instrumentation. 相似文献
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The diamond anvil cell (DAC) is a fundamental device used to explore the properties of materials under extreme pressure and temperature (P/T) conditions. In the past years, simultaneous high P/T DAC experiments using the resistively heated DAC (RH-DAC) techniques have been developed for studying materials properties in a wide P/T range. However, the mechanical instability of metallic gaskets used for sample confinement at high P/T conditions remains a limiting factor for exploiting the accessible P/T range of the RH-DAC. In this study, we present a new gasket configuration that overcomes these limitations. It is based on an amorphous boron–epoxy mixture inserted in a rhenium gasket. We show how these gasket inserts stabilize the sample chamber over a wide P/T range, allowing monitoring sample properties using X-ray diffraction and absorption spectroscopy up to 50?GPa and 1620?K. 相似文献
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