Progress in high pressure EDXD system and research at Beijing Synchrotron Radiation Facility

The synchrotron radiation from a new wiggler of BEPC has been used to high pressure research. Upgraded DAC apparatus and EDXD system have been operated to determine the pressure-induced phase transition of materials at BSRF since June 1998. The improved performance of the system and the preliminary results of the research were described.     

Structural stability of infinite-layer CaCuCO<Subscript>2</Subscript> under high pressure

Since the discovery of high temperature supercon-ductivity by Bednorz et al. in 1986[1], many series of cu- prate superconductors have been synthesized. Critical temperature has been improved continuously. But no verdict has been given upon what mechanism causes su- perconductivity. CaCuO2 conductive layers are the parent structure of the high Tc cuprate superconductors, such as Cu-12 (n-1)n[2], Tl-12(n-1)n[3] and Hg-12(n-1)n[4,5] super- conductor families. In 1988, infinite-layer (Ca0.86S…     

同步辐射装置辐射屏蔽计算的探讨

从第三代同步辐射装置的特点出发 ,提出局部屏蔽的重要性 ,并以光束线前端为例 ,用 M- C方法模拟了 1Ge V的电子在其中的剂量分布 .     

Structure properties for the superconductor MgCNi3 under high pressure with synchrotron radiation

The recent discovery of superconductivity at 39 K in the superconductor MgB2[1] shows that intermetallic compounds with simple structure types are worth serious reconsideration as sources of new superconducting mate-rials. Subsequent to this discovery, He et al. observed a new intermetallic superconductor MgCNi3[2] at about 8 K. The perovskite crystal structure for MgCNi3 is shown in Fig. 1, with the atomic positions: Mg: 1a (0,0,0), C: 1b (0.5,0.5,0.5) and Ni: 3c (0,0.5,0.5). This mater…     

High-Pressure Experimental Studies on Geo-Liquids Using Synchrotron Radiation at the Advanced Photon Source

We review recent progress in studying silicate, carbonate, and metallic liquids of geo-logical and geophysical importance at high pressure and temperature, using the large-volume high-pressure devices ...     

国家同步辐射实验室U14C光束线气体滤波器的研制

为消除波荡器产生的高次谐波对国家同步辐射实验室新建的U14C光束线的影响，同时维持光束线中其他各子系统能在超高真空环境下工作，使用了三级差分抽气滤波系统．测试结果显示，在PAr〈1．333kPa时，光束线真空度维持在〈1．09×10^-6 Pa；往气室内通1．333kPa Ar时，可有效抑制高次谐波的通过，效率达99．97％以上，光束线真空度维持在2．53×10^-7 Pa，有效地降低了气体外泄至光束线的干扰．     

Bi-2223相的高温X-射线衍射研究

对精心制备的,其特性经过深入研究的Ｂｉ１．７Ｐｂ０．３Ｓｒ２Ｃａ２Ｃｕ３Ｏｘ（２２２３相）单相样品,在原位进行了高温Ｘ射线衍射谱研究．结果表明：压力对样品的分解影响很大,在氩气氛中（１０１．３ｋＰａ）,样品大约在７９０℃开始分解;在真空条件下,样品的分解则始于约３００℃．分解的产物很强地依赖于压力．这一研究对带材和线材的制备,对２２２３相晶格不稳定性的理解都具有重要的实际意义．     

Synchrotron X-ray diffraction techniques for in situ measurement of hydride formation under several gigapascals of hydrogen pressure

The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of several gigapascals, hydrogen becomes chemically active and reacts with metals and alloys to form hydrides. This paper covers a high-pressure study of the hydrogenation process and the synthesis of hydrides using a cubic-type multi-anvil apparatus. The experimental details of a hydrogenation cell assembly, high-temperature and highpressure generation, and an in situ observation technique are presented. These experiments are conducted with the aid of in situ synchrotron radiation X-ray diffraction measurements operated in an energy-dispersive mode in the conventional manner for time-resolved measurements and a newly developed angle-dispersive mode for observation of the crystal growth process during formation of metal hydrides. Two successful cases of high-pressure hydrogenation are presented： aluminum hydride, Al H3, and an aluminum-based alloy hydride, Al2 Cu Hx, which are potential candidates for hydrogen storage materials.     

高压相平衡精密实验测定研究

根据现有实验条件,设计,安装了一套静态法高压汽液平衡的测定装置,并通过测定ＣＯ２的饱和蒸汽压检验了该装置的可靠性。     

基于同步辐射白光形貌术和X射线迹线法的6H-SiC单晶结构缺陷研究

[目的]SiC材料结构缺陷的检测和控制是实现材料应用的关键环节,因此本文对6H-SiC单晶中的结构缺陷进行研究。[方法]采用同步辐射白光形貌术观察6H-SiC单晶中的基本螺位错和基平面弯曲,并利用X射线迹线法模拟基本螺位错的形貌和基平面弯曲后衍射斑点的形状。[结果]6H-SiC单晶中的典型结构缺陷之一为基本螺位错,它的形貌特征为白色的圆斑;由于热弹应力的存在,6H-SiC单晶在生长过程中容易发生基平面弯曲,结果导致衍射斑点的形状发生改变。[结论]同步辐射白光形貌术和X射线迹线法可以用于检测6H-SiC单晶结构缺陷;样品的基本螺位错密度为1.56×10~4/cm~2,基平面弯曲半径近似为1m。     

Hard X-ray diffraction enhanced imaging only using two crystals

Different configurations for the monochromator crystals and the analyzer crystals have been used in hard X-ray diffraction enhanced imaging (DEI) methods to overcome the complex task to adjust each of them to the ideal position. Here we present a very compact DEI configuration, and preliminary results of experiments performed at the Beijing Synchrotron Radiation Facility (BSRF) using only two crystals: the first one acting as monochromator and the second one as analyzer in the Bragg geometry. Refraction contrast images characterized by high contrast and spatial resolution are obtained and compared with absorption images. Differences among these images will be outlined and discussed emphasizing the potential capabilities of this very simple layout that guarantees a high transmission efficiency.     

PbTiO_3-CoFe_2O_4磁电材料样品库的同步辐射X射线衍射结构分析

用高分辨微区同步辐射X射线衍射研究了PbTiO3-CoFe2O4组合材料样品库晶体结构随成分的变化,发现在80%PbTiO3成分附近存在着一个由外延应力引起的狭窄立方相区.分析表明,正是此相区的存在造成了该区域介电常数、非线性介电常数和磁电系数异常的增大.     

PbTiO3-CoFe2O4磁电材料样品库的同步辐射X射线衍射结构分析

用高分辨微区同步辐射X射线衍射研究了PbTiO3-CoFe2O4组合材料样品库晶嵌：结构随成分的变化，发现在80％PbTiO3成分附近存在着一个由外延应力引起的狭窄立方相区．分析表明，正是此相区的存在造成了该区域介电常数、非线性介电常数和磁电系数异常的增大．     

基于能量色散X荧光分析法测溶液浓度

目的 溶液浓度是一项重要的计量参数,溶液浓度测量广泛应用于工业和科学研究等领域。为了快速、准确测量溶液浓度,本文提出了能量色散X荧光分析方法。方法 将配制好的10种三氯化铁溶液作为标准溶液,利用能量色散X荧光分析方法测量出溶液中Fe的特征 X 射线峰峰面积,得到三氯化铁溶液的标准曲线,利用该标准曲线,对5组三氯化铁溶液进行了测量。结果 实验结果表明,三氯化铁的浓度与溶液中Fe元素的特征 X 射线峰的峰面积成较好的线性关系。且对五组三氯化铁待测溶液浓度进行数据分析,结果表明实验测得最大误差为1.74%,其他误差都在1%以内,小于传统的折射率测量误差（大约 3%）。另外,为了进一步分析其精确度,分别计算了浓度梯度差。由梯度差可知,最大梯度差为 3.71%,绝大多数在1%以内,最小为0。结论 该方法具有较高的精确度,且出数据快,随测随得,为快速、准确测量溶液浓度提供参考。     

Structural phase transition of edge-sharing copper oxide Ca<Subscript>0.85</Subscript>CuO<Subscript>2</Subscript> under high pressure

The perovskite-like structure compound Ca0.85CuO2 has interesting structural properties: it has infiniteone-dlmensional edge-sharing copper-oxygen chains as wellas partial occupancy of the Ca sites resulting in an incommensurate superstructure. In situ high.pressure energy dispersive X-ray diffraction measurements on polycrystallinepowder Ca0.85CuO2 have been performed by using diamondanvil cell (DAC) instrument with synchrotron radiation. Theresults for the first lime show that edge-sharing copper oxide Ca0.85CuO2 undergoes a structural transition at 14.5 GPa,and furthermore the structural transition is reversible.     

Structure properties for the superconductor MgCNi<Subscript>3</Subscript> under high pressure with synchrotron radiation

In situ high pressure energy dispersive X-ray diffraction measurements on cubic-perovskite superconductor MgCNi₃ under pressure up to 22 GPa have been performed by using diamond anvil cell with synchrotron radiation. We have investigated its crystal structure and compressibility. The results show that the structure of MgCNi₃ is stable under pressure up to 22 GPa. According to Birch-Murnaghan state equation, when we assume B ₀′ = 4, we get B₀ = 267.8 ± 7.2 GPa.