橄榄石的等温状态方程

利用金刚石对顶砧(DAC)高压装置产生高压,使用16∶3∶1的甲醇、乙醇和水混合液体作为传压介质,在室温下,40 GPa的压力范围内,对橄榄石(olivine)进行了原位高压同步辐射能量色散X射线衍射(EDXRD)研究。实验结果表明,在所研究压力范围内,采自张家口大麻坪天然新鲜橄榄石的结构稳定,未见相变和压致非晶现象发生。用Birch-Murnaghan方程对测得的V-p数据进行了数值拟合,当K′T0=4时,橄榄石的零压体弹模量为KT0=141.3±3.2 GPa。     

Synchrotron radiation X-Ray diffraction in situ study of fine-grained minerals in shock veins of Suizhou meteorite

The synchrotron radiation X-ray diffraction technique developed for in situ study at high pressure and temperature has also been used to investigate microscopic mineral inclusions in ultrahigh-pressure metamorphic rocks and deep-mantle samples. Present study added two more examples of successful utilization of synchrotron radiation X-ray diffraction technique for in situ investigations of fine-grained (0.5–30 μm in size) minerals in very thin shock melt veins of the Suizhou meteorite: (i) X-ray diffraction measurement of extremely small-sized vein matrix minerals, and (ii) identification of the micron-sized new mineral tuite embedded in the vein matrix. It has been revealed that the fine-grained vein matrix consists of well crystallized garnet, kamacite and troilite, and the powder diffraction pattern consisting of 17 lines with d-values, intensities (I), relative intensities (I/I ^o) and Miller indices, as well as the cell parameters for the new mineral tuite has also been successfully obtained. The result of present investigations has enriched the content of dynamic high-pressure mineralogy and that of Earth’s mantle geochemistry.     

Neutron Activation Analysis, Atomic Absorption and X-Ray Fluorescence Spectrometry Review for 2003

This review for the year 2003 deals with three relatively well-established, mature, analytical techniques (neutron activation analysis, atomic absorption spectrometry and X-ray fluorescence spectrometry) that nevertheless remain very important for the characterisation of geological and environmental samples. Developments in neutron activation analysis included modification to the technique in relation to the determination of platinum-group elements, as well as consideration of sample size in ore grade estimation. A considerable body of literature was published on the application of atomic absorption spectrometry in the analysis of environmental samples. Many of these proposed technical and methodological improvements, notably in extraction procedures. X-ray fluorescence spectrometry saw developments in in situ analysis, synchrotron micro-XRF (μ-SRXRF) and a confocal X-ray set-up for 3D elemental imaging. XRF technologies were used in the analysis of geological samples, reference materials, glasses, solutes and environmental materials.     

同步辐射光成像中的最大似然迭代重建法

本研究主要目的在于探讨与评估在同步辐射光源显微成像时使用不同的图像重建算法时的图像质量与重建速度.此次实验我们采用鸟类的羽毛做为受测物体,并且使用位于新竹科学工业园区内的同步辐射研究中心的同步辐射光源及高分辨X光摄影机来取得X光的影像.本研究使用两种不同的算法来重建图像,分别为滤波反投影法与梯度最大似然迭代重建法,作为这次评估的算法.由重建图像的结果显示,我们可以发现梯度最大概似迭代式重建法在边缘的地方有模糊化的现象,另外在图像质量方面,滤波反投影算法的影像上的环状伪影较梯度最大似然迭代算法明显.因此本研究就针对目前同步辐射的图像重建法做一探讨,并对两种不同的重建算法做一适当的评估,以期望提供不同的图像重建法给予不同需求的使用者.     

同步辐射的局际性

由于同步幅射机制在天体物理应用中取得了巨大成功,近十多年来已出现滥用的趋势,“幂律能谱的电子－定辐射幂律谱”的传统观念其实有错误,对非均匀磁场,正确的公式应该是同步－曲率辐射公式,而不是同步辐射公式,将一般磁场都看成平衡匀匀场,用同步辐射讨论,很可能导致对天体情况的错误描述。     

Deviatoric stress in a diamond anvil cell using synchrotron radiation with two diffraction geometries

Deviatoric stress in a diamond anvil cell with gold as a pressure and stress indicator is measured by two complementary techiques using synchrotron radiation. The first method employs a white X-ray beam using energy disperisive X-ray diffraction. The incident X-ray beam is parallel to the load axis and the diffraction pattern is recorded at a low two-theta angle. Using powder diffraction patterns of polycrystallin gold, we measured the elastic strain of two crystal planes oriented normal to the diffraction vector. Stresses nearly parallel and perpendicular to the load axis can be calculated by stress-strain tensor relatonship. The other method uses a monochromatic wiggler X-ray beam. In this case, the diamond cell is oriented so that the incident beam is perpendicular to the load axis. The diffraction pattern is recorded on an image plate area detector. Elastic strains responding to stresses perpendicular and parallel to the load axis can be measured and stresses of the same orientations can be calculated from the strain data. These measurements provide a lower bound of the actual differential stress in a diamond cell. With these techniques, we can measure stress distribution in a less deviatoric gasketted sample and determine yield strength of mantle materials at high pressures and temperatures.     

天然金刚石同生位错的同步辐射X射线貌相研究

利用同步辐射白光透射貌相术研究了辽南天然金刚石的晶体缺陷。采用作者提出的计算晶体缺陷空间取向的方法计算了金刚石中位错的取向。晶体中所有位错均起源于晶核，并且柏氏矢量都平行于[1^-01]。多数位错并非位于{111}面内。位错所在晶面属于[1^-01]晶带，并且多数与{211}或{110}面近于平行。位错线平直，部分有拐折。所有位错均为混合位错。位错走向与生长面近于垂直，多数与＜111＞夹角较小。所有位错均为同生位错，形成后未发生滑移。晶核在形成期曾受到较大应力作用造成较大的晶格畸变。晶体内部未出现生长带，反映晶体成长过程中环境未发生大的变化。形成晶体的碳质来源不均一，反映了中元古代华北陆台下地壳岩浆成分的不均一性。     

Determination of phase transition pressures of ZnTe under quasihydrostatic conditions

Pressure behavior of ZnTe at room temperature was studied using an X-ray energy dispersive method on a DIA type cubic anvil apparatus (SAM-85) at NSLS-X17B1. By using powdered polyethylene, the sample and NaCl for a pressure scale were held under quasihydrostatic conditions, which were confirmed by X-ray diffraction method. Two high-pressure phase transitions were confirmed using X-ray powder diffraction simultaneously with electrical resistance measurements. The phase transition pressures under quasihydrostatic conditions were determined to be 9.6 GPa, at which the resistance increased, and 12.0 GPa, which was the midpoint of a large resistance decrease. Errors in the pressure determinations were estimated to be less than 0.2 GPa. These pressure values may depend on grain size and anisotropic stress effects on the calibrant. From X-ray observation of ZnTe, the bulk modulus of the zinc blende structure was calculated to beK ₀=51(3) GPa andK ₀ =3.6(0.8), and the first transition at 9.6 GPa was found to have about 9% volume change. It was consistent with an anomaly in the pressure generating curves.     

关于研制X射线荧光微分析标准物质的探讨

将经过高温处理的土壤样品进行反复研磨后，用于X射线荧光微分析标准物质的研制，当99％的粉末粒径≤30μm时，用仪器中子活化和同步辐射X射线荧光进行元素分布均匀性和最少取样量分析，结果表明24个元素的最少取样量可以降到约1mg。