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.     

The poisoning and regeneration effect of alkali metals deposed over commercial V2O5-WO3/TiO2 catalysts on SCR of NO by NH3

In this study, commercial V2O5-WO3/TiO2 catalysts were deactivated by loading with alkali metals （K and Na）. These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4 （through the ultrasonic-assisted method）. The samples used in this research were characterized by NH3-temperature programmed desorption （TPD）, and X-ray photoelectron spectroscopy （XPS）. Results showed that Na2O and KaO doping can poison the V2O5-WO3/TiO2 catalyst and that the poisoning effect of Na2O was stronger than that of KaO. However, the Na2O-loaded sample was easier to regenerate than the KaO-loaded sample. The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface. SO42- could also promote catalyst activity. As indicated by the NH3-TPD findings, the deposition of Na2Oand K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites, especially strong chemisorption sites. XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxy- gen [the Oα（Oα ＋ Oβ） ratio]. In the Na2O-doped catalyst, much chemisorbed oxygen was lost （from 28.8 % to 10.6 %）. However, the decrease in the Oα（Oα ＋ Oβ） ratio was less significant in the K20-doped catalyst （from 28.8 % to 23.5 %）. Nonetheless, the binding energies of Ols broadened with respect to both high and low energy. Inparticular, the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.     

各向同性火球中考虑同步自吸收的伽玛暴余辉

基于Huang,Y．F．等人的统一动力学模型，研究了星际介质环境下各向同性火球所抛壳层的动力学量随时间的演化，考虑了同步自吸收效应，用数值计算方法得到不同频率下随时间演化的伽玛暴余辉，同柱状喷流下伽玛暴余辉比较，得出相应结论．     

质量比为0．2％ZnO掺杂Ba0．2Sr0．8TiO3与Ba0．2Sr0．8TiO3陶瓷的结构和变温变频复介电常数的对比测量分析

采用固相反应方法合成了（1-x％）Ba0.2Sr0.8TiO3＋x％ZnO（x=0,0．2）陶瓷材料,并分别用x射线衍射和变温变频介电谱方法,对它们的结构和复介电常数进行了对比测量分析．结果表明,质量比为0．2％ZnO的掺杂：（1）对样品的室温晶系类型没有影响,仍然为立方晶系,晶格常数仅仅减小了0．18％;（2）弥散铁电相变的相变温度由未掺杂的136K向高温移动至140K;（3）低温铁电相的复介电常数的实部ε′减小而虚部ε”增加,高温顺电相的ε’和ε″几乎不变;（4）样品中弥散铁电相变过程的ε″与测量频率f几乎无关;（5）样品中出现在高温区的离子扩散过程向低温移动．     

本研制出世界最短波长X射线激光

[新华网]日本研究人员近日利用X射线自由电子激光装置成功发射出波长仅0.12纳米的X射线激光,刷新了这种激光最短波长的世界纪录。根据日本理化研究所和高辉度光科学研究中心联合发布的新闻公报,来自这两家机构的研究人员利用建在兵库县的X射线自由电子激光装置发出了波长仅0.12纳米的X射线激光,打破了美国的直线加速器相干光源于2009年4月创下的0.15纳米的最短波长世界纪录。     

P123/H2O/SDS新型溶致液晶的制备及表征

制备非离子表面活性剂P123(聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO))、十二烷基硫酸钠(SDS)和水形成的3组分体系液晶并研究其性质.采用偏光显微镜(POM)及小角X射线散射技术(SAXS),观测体系内各组分不同质量分数时的双折射现象和液晶织构,并确定样品相态.结果表明:当wP123=w(H2O)=45...     

费米伽玛射线空间望远镜最初3个月观测Blazar的射电和伽玛射线辐射研究

以费米伽玛射线空间望远镜运行来最初3个月观测的Blazar为样本,给出了74个(46个平谱射电类星体,28个BL Lac天体)伽玛射线噪Blazar天体的射电(5 GHz)和伽玛射线流量,计算了射电到伽玛射线辐射的有效谱指数αRγ.研究了有效谱指数及射电光度与伽玛射线光度的关系.结果表明:对于射电和伽玛射线光度都有一个...     

水超脉泽源：[OIV]发射线和脉泽辐射

水超脉泽辐射光度很大,因此活动星系核被公认为是其唯一的能源,而近来[OIV]发射线被认为可以准确地示踪活动星系核各向同性的强度．为了分析活动星系核和脉泽辐射间的内在联系,对所有发表的水脉泽星系的（OIV]发射线观测资料进行了全面调研和收集．整个脉泽样本和3个恒星形成脉泽的[oIV]线的平均光度分别为10^7.09±0.17和10^-6.55太阳光度．对比脉泽星系和非脉泽星系样本的[OIV]光度,没有发现大的差别．对于同活动星系核成协的脉泽星系,发现它们的[OIV]光度和水脉泽光度间存在一个明显的相关,尽管存在较大的弥散．如果活动星系核是脉泽辐射的能量激发源,那么这一相关性为[OIV]发射线可以很好示踪活动星系核强度的观点提供了支持．     

伽玛分布参数的极大似然估计数值解法

当伽玛分布的形状参数和位置参数均未知时,利用极大似然法对伽玛分布的参数进行估计时,该似然方程组没有解析解。为此,根据牛顿—拉夫森算法的迭代原理,通过引入一个修正因子对每次迭代的结果予以修正,以提高其迭代的计算精度,从而将改进的牛顿—拉夫森算法应用于求解似然方程组的数值解。最后,给出两个数值模拟算例进行验证和比较。     

北京市射线应用研究中心

北京市射线应用研究中心(以下简称射线中心)创建于1987年,隶属于北京市科学技术研究院。射线中心是由国际原子能机构资助,和有关部门共同投资建立的核技术产业化示范基地。2000年由事业单位转制为科技型企业,2006年通过北