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The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies 被引量:6
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作者 黄俊杰 宋艳英 +3 位作者 马冬冬 郑燕萍 陈明树 万惠霖 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第7期1229-1236,共8页
Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface c... Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface composition of the supported alloy nanoparticles to understand the nature of the catalytically active sites. In this paper, homogeneous face-centered cubic PtCu nanoparticles with a narrow particle size distribution were successfully fabricated and dispersed on a high-surface-area Ti〇2 powder support. The samples were oxidized and reduced in situ and then introduced into the ultrahigh vacuum chamber to measure the topmost surface composition by high-sensitivity low-energy ion scattering spectroscopy, and to determine the oxidation states of the elements by X-ray photoelectron spectroscopy. The surface composition and morphology, elemental distribu-tion, and oxidation states of the components were found to be significantly affected by the support and treatment conditions. The PtCu is de-alloyed upon oxidation with CuO wetting on the TiO2 sur-face and re-alloyed upon reduction. Phase diagrams of the surface composition and the bulk com-position were plotted and compared for the supported and unsupported materials. 展开更多
关键词 PtCu alloy Bimetal catalyst Surface composition Phase diagram In situ xPS-LEIS
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新型3D合金屏蔽效能的MCNP模拟 被引量:3
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作者 刘珉强 朱小锋 杜川华 《吉林大学学报(理学版)》 CAS 北大核心 2020年第4期988-991,共4页
用Monte Carlo程序(MCNP)模拟研究不同掺杂组分与不同掺杂质量分数合金对低能X射线谱的屏蔽效能.模拟结果表明:合金的屏蔽效能与掺杂组分原子序数呈正相关,与掺杂质量分数呈正相关(ΔZ>0)或负相关(ΔZ<0);ΔZ绝对值越大,合金的屏... 用Monte Carlo程序(MCNP)模拟研究不同掺杂组分与不同掺杂质量分数合金对低能X射线谱的屏蔽效能.模拟结果表明:合金的屏蔽效能与掺杂组分原子序数呈正相关,与掺杂质量分数呈正相关(ΔZ>0)或负相关(ΔZ<0);ΔZ绝对值越大,合金的屏蔽效能变化越大,且变化幅度与掺杂质量分数呈正相关;TaW合金的屏蔽效能最好,掺杂质量分数的变化对其屏蔽性能影响最小;在低能能谱范围内,不同能量X射线透射率的MCNP模拟结果与实验结果基本一致. 展开更多
关键词 Monte Carlo模拟 低能x射线谱 屏蔽效能 掺杂质量分数 掺杂组分原子序数
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Characteristics of Amorphous Silicon Nitride Films Deposited by LF-PECVD from SiH_4/N_2
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作者 ZHONG Zhi-qin ZHANG Yi YU Zhi-wei DAI Li-ping ZHANG Guo-jun WANG Yu-mei WANG Gang WANG Shu-ya 《Semiconductor Photonics and Technology》 CAS 2009年第3期145-148,共4页
Amorphous silicon nitride films were deposited by low-frequency plasma-enhanced chemical vapor deposition(LF-PECVD) using silane and nitrogen as precursors. Characteristics such as deposition rate, surface morpholog... Amorphous silicon nitride films were deposited by low-frequency plasma-enhanced chemical vapor deposition(LF-PECVD) using silane and nitrogen as precursors. Characteristics such as deposition rate, surface morphology, and chemical composition were measured by spectroscopic ellipsometry(SE), atomic force mieroscope(AFM) and x-ray photoelectron spectroscopy(XPS). It was shown that amorphous silicon nitride film could be prepared by LF-PECVD with good uniformity and even surface. The XPS result indicated that a small quantity of oxygen was involved in the sample, which was discussed in this paper. 展开更多
关键词 SiNx SE AFM xPS PECVD
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