检索结果-南通市图书馆

Formation and transformation of metastable LPSO building blocks clusters in Mg-Gd-Y-Zn-Zr alloys by spinodal decomposition and heterogeneous nucleation

引用

Journal of Magnesium and Alloys 2024年第2期12卷 673-686页

作者： Xin Zhao Zhong Yang Jiachen Zhang Minxian Liang Liying Wang School of Materials Science and Chemical Engineering Xi’an Technological UniversityXi’an 710021China Xi’an Tianli Metal Composite Material Co.Ltd. Xi’an 710299China

To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)structures in the Mg-Gd-Y-Zn-Zr alloy annealed at 300℃~500℃.Various types of metastable LPSO building block clusters were found to exist in alloy structures at different temperatures,which precipitate during the solidification and homogenization *** stability of Zn/Y clusters is explained by the first principles of density functional *** LPSO structure is distinguished by the arrangement of its different Zn/Y enriched LPSO structural units,which comprises local fcc stacking sequences upon a tightly packed *** presence of solute atoms causes local lattice distortion,thereby enabling the rearrangement of Mg atoms in the different configurations in the local lattice,and local HCP-FCC transitions occur between Mg and Zn atoms occupying the nearest neighbor *** finding indicates that LPSO structures can generate necessary Schockley partial dislocations on specific slip surfaces,providing direct evidence of the transition from 18R to *** of the LPSO,devoid of any defects and non-coherent interfaces,was observed separately from other precipitated *** a result,the precipitation sequence of LPSO in the solidification stage was as follows:Zn/Ycluster+Mg layers→various metastable LPSO building block clusters→18R/24R LPSO;whereas the precipitation sequence of LPSO during homogenization treatment was observed to be as follows:18R LPSO→various metastable LPSO building block clusters→14H *** these,14H LPSO was found to be the most thermodynamically stable structure.

关键词： LPSO Spinodal decomposition Homogenization treatment clusters Phase transformation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical study of CO2 hydrogenation to methanol on isolated small Pdx clusters

引用

Journal of Energy Chemistry 2019年第8期28卷 79-87,I0004页

作者： Adhitya G.Saputro Refaldi I.D.Putra Arifin L.Maulana Muhammad U.Karami Mochamad R.Pradana Mohammad K.Agusta Hermawan K.Dipojono Hideaki Kasai Engineering Physics Research Group Institut Teknologi BandungBandung 40132 Indonesia Research Center for Nanosciences and Nanotechnology Institut Teknologi BandungBandung 40132 Indonesia Akashi College National Institute of TechnologyHyogo 674-8501 Japan Graduate School of Engineering Osaka UniversityOsaka 565-0871 Japan Department of Applied Physics Osaka UniversityOsaka 565-0871 Japan

CO2 hydrogenation to methanol on small size Pdxclusters(x = 7, 9 and 13) has been studied using density functional theory calculations. It has been found that in contrast to metallic Pd system, these small Pdxclusters can interact well with CO2 molecule. CO2 molecule can be adsorbed with a bidendate configuration on the Pdxclusters. The formation of CO2 bidendate adsorption configuration facilitates the first step of CO2 hydrogenation reaction on the clusters. The energy profiles for formate pathway and reverse water gas shift + CO hydrogenation pathways on Pdxclusters are quite similar with Cu(111) surface, except for the first and last hydrogenation steps where the Pdxclusters have lower activation energies. This improvement causing the Pdxclusters to have a tolerable turn over frequencies values. In general, the usage of Pd in the form of small size cluster can improve the catalytic performance of metallic Pd for the CO2 hydrogenation to methanol because small size Pd cluster can act not only as an H2 dissociation center but also as a CO2 hydrogenation center.

关键词： Pdx clusters CO2 Adsorption Hydrogenation Methanol Density functional theory

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Density functional study of Ag_(n-1)Y(n=2-10) clusters

引用

Chinese Physics B 2011年第11期20卷 176-182页

作者：刘小勇朱正和盛勇 College of Material Science and Engineering Sichuan University Institute of Atomic and Molecular Physics Sichuan University

Employing the density functional theory, we investigate the lowest-energy geometric, the stable and the electronic properties of Ag_n-lY （n = 2-10） clusters in this paper. The structural optimization and the frequency analysis are performed at the B3LYP/LANL2DZ level. Meanwhile, the differences in geometry, stability and electronic properties between Agn and Ag_n-lY （n = 2-10） clusters are also studied. The results show that for the doping of the yttrium atoms, the structures and the average binding lengths of the Agn clusters are greatly changed. In addition, the thermodynamic stabilities of the Agn clusters are enhanced generally with the doping of the Y atoms. In addition, the chemical stabilities of the Ag_n-lY clusters are still improved compared with that of the three-dimensional Agn clusters.

关键词： clusters Ag_n-lY stability electronic properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Unsaturated bi-heterometal clusters in metal-vacancy sites of 2D MoS2 for efficient hydrogen evolution

引用

Carbon Energy 2024年第3期6卷 264-275页

作者： Gonglei Shao Jie Xu Shasha Gao Zhang Zhang Song Liu Xu Zhang Zhen Zhou Interdisciplinary Research Center for Sustainable Energy Science and Engineering(IRC4SE2) School of Chemical EngineeringZhengzhou UniversityZhengzhouHenanChina College of Chemistry and Materials Engineering Wenzhou UniversityWenzhouZhejiangChina Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) College of ChemistryNankai UniversityTianjinChina State Key Laboratory of Chemo/Biosensing and Chemometrics Institute of Chemical Biology and Nanomedicine(ICBN)College of Chemistry and Chemical EngineeringHunan UniversityChangshaHunanChina Institute of New Energy Material Chemistry School of Materials Science and EngineeringNankai UniversityTianjinChina

The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation ***,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum *** unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active *** them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical ***,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.

关键词： clusters hydrogen evolution reaction metal vacancy MoS2 unsaturated heterometal

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances of Synergistic Electrocatalysis Between Single Atoms and Nanoparticles/clusters

引用

Nano-Micro Letters 2024年第11期16卷 377-412页

作者： Guanyu Luo Min Song Qian Zhang Lulu An Tao Shen Shuang Wang Hanyu Hu Xiao Huang Deli Wang Key Laboratory of Material Chemistry for Energy Conversion and Storage(Huazhong University of Science and Technology)Ministry of Education School of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China

Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient *** synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and *** this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are ***,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are ***,several clean energy catalytic reactions performed over the synergistic composite catalysts are ***,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.

关键词： Single atoms Nanoparticles clusters Synergistic composite catalysts Synergistic effect

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The effect of neighbor distance of magnetic nanoparticle clusters on magnetic resonance relaxation properties

引用

Science Bulletin 2016年第13期61卷 1023-1030页

作者： Dan Wang Bingbing Lin Taipeng Shen Jun Wu Chunchao Xia Bin Song Hua Ai National Engineering Research Center for Biomaterials Sichuan University Department of Radiology West China Hospital Sichuan University

Superparamagnetic iron oxide （SPIO） nanoparticle clusters are one unique form which can enhance magnetic relaxivity and improve the magnetic resonance imaging contrast at the same iron concentration, comparing to single SPIO nanoparticles. Controlling of cluster size and other structural parameters have drawn great interests in this field to further improve their magnetic properties. In this study, we investigated how the interparticle distance （also known as neighbor distance） of SP10 nanocrystals within clusters affect their magnetic relaxation behaviors. To adjust the neighbor distance, different amount of cholesterol （CHO） was chosen as model spacers embedded into SPIO nanocluster systems with the help of amphiphilic diblock copolymer poly（ethylene glyco）-polyester. Small- angle X-ray scattering was applied to quantify the neighbor distance of SPIO clusters. The results demonstrated that the averaged SPIO nanocrystal neighbor distance of nan- oclusters increased with higher amount of added CHO. Moreover, these SPIO nanocrystal clusters had the promi- nent magnetic relaxation properties. Simultaneously, con- trolling of SPIO nanocrystal neighbor distance can regulate the saturation magnetization （Ms） and magnetic resonance （MR） T2 relaxation of the aggregation, and ultimately obtain better MR contrast effects with decreased neighbor distance.

关键词： Iron oxide nanoparticle clusters Neighbor distance Magnetic properties T2relaxation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Density Functional Theory Study on the Adsorption of Dioxygen on Small Pt-Pd clusters

引用

Chinese Journal of Structural Chemistry 2007年第1期26卷 63-78页

作者：李钠官文佳王艳丽马琳孙仁安孙公权 School of Chemistry and Chemical Engineering Liaoning Normal University Direct Alcohol Fuel Cell Laboratory Dalian Institute of Chemical PhysicsThe Chinese Academy of Sciences

The electronic and physical properties of PtmPdn （m＋n≤5） metal clusters and their interactions with dioxygen have been studied by using hybrid density functional B3LYP method. The total energies, atomization energies, vibration frequencies, and charge distributions were reported. The Pt-Pt bridge site modified by Pd atoms was found to be the most active site for the dissociation of dioxygen, which was mainly due to the change of electronic structures of the Pt atoms in bimetallic Pt-Pd clusters.

关键词： clusters bridge site charge transfer density functional theory method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The characteristics of clusters of weather and extreme climate events in China during the past 50 years

引用

Chinese Physics B 2012年第1期21卷 549-557页

作者： Yang Ping Hou Wei Feng Guo-Lin Institute of Urban Meteorology China Metrology AdministrationBeijing 100089China Laboratory for Climate Studies China Meteorological AdministrationBeijing 100081China

The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years. The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s, and its strength was enhanced. On the other hand, the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale. Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years, and have different cluster characteristics because of their definitions. Regions with high clustered indexes are concentrated in southern China. The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years.

关键词： extreme event clusters decadal clustered index

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Understanding ultra-dispersed CeO_(x)modified iridium clusters as bifunction electrocatalyst for high-efficiency water splitting in acid electrolytes

引用

Journal of Rare Earths 2023年第2期41卷 208-214页

作者： Xiaojie Zhao Ying Chang Xiaolong He Huiqi Zhang Jingchun Jia Meilin Jia Inner Mongolia Key Laboratory of Green Catalysis and Inner Mongolia Collaborative Innovation Center for Water Environment Safety College of Chemistry and Environmental ScienceInner Mongolia Normal UniversityHohhot 010022China

Designing bifunctional catalysts with high catalytic activity and durability for electrochemical water splitting has become a promising approach to producing clean and sustainable hydrogen *** high specific surface area and ultra-small size,metal clusters have become a kind of promising *** introducing Ce species,the noble metal iridium(Ir)can be electronically modulated,thus reduce the activation energy of intermediate,and improve the intrinsic catalytic activity for practical *** performance of Ir_(3)CeO_(x)/C is more prominent among different feeding ratios of the *** overpotential is only 299 mV for the oxygen evolution reaction(OER),and the overpotential is only23 mV for the hydrogen evolution reaction(HER)at 10 mA/cm^(2) in acid *** Ir doped with appropriate amount of Ce can obtain excellent OER and HER performance and catalyze water splitting *** work provides a strategic approach to the formation of clusters of precious metals and rare earths.

关键词： clusters Oxygen evolution reactions Hydrogen evolution reactions Oxygen vacancies Rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hydrolyzed Al(Ⅲ) clusters:Speciation stability of nano-Al_(13)

引用

Journal of Environmental Sciences 2011年第5期23卷 705-710页

作者： Shuifeng Wang Chihpin Huang Christopher W K. Chow Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. E-mail: wgds@*** Institute of Environmental Engineering National Chiao Tung University Hsinchu Taiwan China Australian Water Quality Centre SA Water Corporation 250 Victoria Square Adelaide SA 5000 South Australia

Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy （PCS）, and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations （0.5-2.11 tool/L） were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the eTA1-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, All3 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90~C.

关键词： nano-All3 clusters inorganic polymer flocculant speciation stability

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：