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The α-phase in Zr-2.5 Nb pressure tubes has been analysed after irradiation with neutrons for temperatures between 523 and 573 K. The α-phase contains Nb in supersaturated solid solution (about 0.5−1 wt% Nb) in the as-fabricated condition. Irradiation results in the formation of small discrete precipitates having diameters of about 5 nm. Energy Dispersive X-ray (EDX) analysis using a scanning transmission electron microscope (STEM) was complicated by the presence of a self-generated X-rays in the irradiated material and by the fact that the precipitates were small relative to the foil thickness (typically 100–200 nm). Techniques developed to measure segregation of impurities at interfaces were employed to show that the precipitates were Nb-rich, their formation being consistent with a decrease in Nb concentration in the matrix. 相似文献
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Dr. Shun Dekura Prof. Hirokazu Kobayashi Dr. Kohei Kusada Prof. Hiroshi Kitagawa 《Chemphyschem》2019,20(10):1158-1176
One of the key issues for an upcoming hydrogen energy-based society is to develop highly efficient hydrogen-storage materials. Among the many hydrogen-storage materials reported, transition-metal hydrides can reversibly absorb and desorb hydrogen, and have thus attracted much interest from fundamental science to applications. In particular, the Pd−H system is a simple and classical metal-hydrogen system, providing a platform suitable for a thorough understanding of ways of controlling the hydrogen-storage properties of materials. By contrast, metal nanoparticles have been recently studied for hydrogen storage because of their unique properties and the degrees of freedom which cannot be observed in bulk, i. e., the size, shape, alloying, and surface coating. In this review, we overview the effects of such degrees of freedom on the hydrogen-storage properties of Pd-related nanomaterials, based on the fundamental science of bulk Pd−H. We shall show that sufficiently understanding the nature of the interaction between hydrogen and host materials enables us to control the hydrogen-storage properties though the electronic-structure control of materials. 相似文献
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Masaki Tanaka Daichi Izumi Nobuyuki Yoshimura Genichi Shigesato Manabu Hoshino Kohsaku Ushioda 《哲学杂志》2013,93(31):2915-2930
AbstractThe temperature dependence of the yield stress, effective stress and activation volume on the Cu content in steel was assessed using polycrystalline ultra-low carbon steels with 0.5, 1 and 2 mass% Cu added. A small hump was seen in the effective stress–temperature curve for ultra-low carbon steel, which has also been reported for high-purity single-crystal iron. The effective stress was found to decrease with increasing the Cu content. The activation volume was found to be linearly related to the temperature at low temperatures for all types of specimens considered. The activation volume was found to increase abruptly at a certain temperature, which increased with increasing the Cu content. The change in the relationship of the activation volume to temperature is discussed in this paper with respect to the thermally activated process of dislocation glide from the Peierls mechanism to the interaction between dislocations and solute Cu atoms. 相似文献
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稀土发光材料和固溶体发光材料受到人们的广泛关注,稀土固溶体发光材料本身的结构特性在一定程度上能够影响和决定它的发光特性,而发光特性又直接关系到材料的性能和使用前景.因此,本论文的主要工作时通过改变固溶体发光材料CaxSr2-xSiO4: 0.01Eu2+ , 0.01Dy3+固溶离子Ca和Sr的比例浓度来实现对固溶体发光材料基质结构的调节,测得了不同固溶比例下的样品的激发光谱和部分发射光谱以及热释光谱,并对这些实验结果进行分析. 相似文献
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Heng Zhang Chunmei Li Gebrekidan Gebresilassie Eshetu Stphane Laruelle Sylvie Grugeon Karim Zaghib Christian Julien Alain Mauger Dominique Guyomard Tefilo Rojo Nuria Gisbert‐Trejo Stefano Passerini Xuejie Huang Zhibin Zhou Patrik Johansson Maria Forsyth 《Angewandte Chemie (International ed. in English)》2020,59(2):534-538
Lithium‐ion batteries (LIBs) have become ubiquitous power sources for small electronic devices, electric vehicles, and stationary energy storage systems. Despite the success of LIBs which is acknowledged by their increasing commodity market, the historical evolution of the chemistry behind the LIB technologies is laden with obstacles and yet to be unambiguously documented. This Viewpoint outlines chronologically the most essential findings related to today's LIBs, including commercial electrode and electrolyte materials, but furthermore also depicts how the today popular and widely emerging solid‐state batteries were instrumental at very early stages in the development of LIBs. 相似文献
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Solid‐Solution Alloy Nanoparticles of the Immiscible Iridium–Copper System with a Wide Composition Range for Enhanced Electrocatalytic Applications
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Dr. Fenglong Wang Dr. Kohei Kusada Dr. Dongshuang Wu Tomokazu Yamamoto Takaaki Toriyama Prof. Syo Matsumura Dr. Yusuke Nanba Prof. Michihisa Koyama Prof. Hiroshi Kitagawa 《Angewandte Chemie (International ed. in English)》2018,57(17):4505-4509
For the first time, we synthesize solid‐solution alloy nanoparticles of Ir and Cu with a size of ca. 2 nm, despite Ir and Cu being immiscible in the bulk up to their melting over the whole composition range. We performed a systematic characterization on the nature of the IrxCu1?x solid‐solution alloys using powder X‐ray diffraction, scanning transmission electron microscopy coupled with energy‐dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy. The results showed that the IrxCu1?x alloys had a face‐centered‐cubic structure; charge transfer from Cu to Ir occurred in the alloy nanoparticles, as the core‐level Ir 4f peaks shifted to lower energy region with the increase in Cu content. Furthermore, we observed that the alloying of Ir with Cu enhanced both the electrocatalytic oxygen evolution and oxygen reduction reactions. The enhanced activities could be attributed to the electronic interaction between Ir and Cu arising from the alloying effect at atomic‐level. 相似文献
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Bo Huang Hirokazu Kobayashi Tomokazu Yamamoto Takaaki Toriyama Syo Matsumura Yoshihide Nishida Katsutoshi Sato Katsutoshi Nagaoka Masaaki Haneda Wei Xie Yusuke Nanba Michihisa Koyama Fenglong Wang Shogo Kawaguchi Yoshiki Kubota Hiroshi Kitagawa 《Angewandte Chemie (International ed. in English)》2019,58(8)
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ZnS1-x Tex薄膜具有高效的发光特性.样品可观测到强烈的光致发光,随着Te含量x的不同,发射光的颜色从深蓝到黄变化,使其成为制作短波长光波段光电子器件和紫外探测器的理想材料.本文介绍了ZnS1-x Tex多晶薄膜真空蒸发制备的情况,并用X射线衍射仪对淀积在玻璃、石英玻璃和单晶硅衬底上的多晶薄膜进行结构分析,用紫外-可见分光光度计、荧光光谱分析仪对样品的光吸收和发光性质进行研究.分析表明,该薄膜的结构符合闪锌矿的特征.紫外-可见吸收光谱显示该样品在紫外光区有一个强烈的吸收峰,可见光区的吸收很微弱.光致发光光谱表明,样品在可见光区有一个以470nm为中心的发射峰,发射光肉眼可见.该多晶薄膜基本保持了单晶薄膜的紫外吸收、光致发光等良好特性. 相似文献
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Structures and Intramolecular Motions of Special Polycyclic Germanium(II) Amides Compounds of the general formula MeSi(NtBu)3Ge2X (X = Cl ( 1 ), N(SiMe3)2 ( 2 ), P(C6H5)2 ( 3 )) have been synthesized and characterized by X-ray structure analyses and multinuclear NMR-spectroscopy. The temperature dependent NMR investigations of 2 in solution show bond fluctuations concerning the metal-nitrogen bonds and ElMe3 (El = C, Si) rotations. Some of these intramolecular motions also occur in the solid state as detected by means of temperature dependent 13C CP/MAS NMR spectroscopy. The special nature of these NMR spectroscopically detected movements in solution are compared with the results of the X-ray structure analyses. A model of the dynamical behaviour of 2 in solution suggests a quasi circular movement of the two germanium atoms within the molecular cage. After the phase transition from solution to the solid state at ambient temperature this special metal fluctuation is stopped. In the solid state the rotations of the SiMe3 groups in 2 are only hindered at low temperatures. 相似文献