检索结果-内蒙古大学图书馆

Topics in the theory of amorphous materials

EUROPEAN PHYSICAL JOURNAL B 2009年第1期68卷 1-21页

作者： Drabold, D. A. Trinity Coll Cambridge CB2 1TQ England Ohio Univ Dept Phys & Astron Athens OH 45701 USA

In this Colloquium, I describe some current frontiers in the physics of semiconducting amorphous materials and glasses, including a short, but self-contained discussion of techniques for creating computer models, among them the quench from the melt method, the Activation-Relaxation Technique, the decorate and relax method, and the experimentally constrained molecular relaxation scheme. A representative study of an interesting and important glass (amorphous GeSe3:Ag) is provided. This material is a fast-ion conductor and a serious candidate to replace current FLASH memory. Next, I discuss the effects of topological disorder on electronic states. By computing the decay of the density matrix in real space, and also computing well-localized Wannier functions, we close with a quantitative discussion of Kohn's Principle of Nearsightedness in amorphous silicon.

关键词： Disordered solids structural modeling: serial-addition models, computer simulation Glasses Amorphous semiconductors, metallic glasses, glasses Theories and models, localized states Theory of diffusion and ionic conduction in solids Electronic structure of disordered solids

来源：评论

学校读者我要写书评

暂无评论

A multi-range order parameter for binary alloy bulk materials and nanoparticles

引用

EUROPEAN PHYSICAL JOURNAL D 2009年第1-3期52卷 51-54页

作者： Atanasov, I. S. Hou, M. Univ Libre Bruxelles Brussels Belgium Bulgarian Acad Sci Inst Elect BU-1784 Sofia Bulgaria

A multi-range order parameter for binary alloys is considered, valid for bulk materials and nanoparticles. The difference between two common definitions is discussed, arising when applied to small systems. Its properties are illustrated on the example of the order/disorder transitions in Au-Pd fcc bulk materials and nanoparticles. The thermodynamic equilibrium states of these systems are predicted by Metropolis Monte Carlo sampling in the canonical (NPT) ensemble and an embedded-atom model potential. Short range order is found partially preserved by the transition while long range order vanishes. The order of intermediate ranges is found to be particularly sensitive to the presence of anti-phase boundaries (APBs) in both, bulk alloys and nanoparticles.

关键词： Structure of clusters Order-disorder transformations Alloys structural modeling: serial-addition models, computer simulation

来源：评论

学校读者我要写书评

暂无评论

Critical states and phase diagram in the packing of uniform spheres

引用

EPL 2009年第4期86卷 46003 (6pp-46003 (6pp页

作者： Dong, K. J. Yang, R. Y. Zou, R. P. An, X. Z. Yu, A. B. Univ New S Wales Sch Mat Sci & Engn Lab Simulat & Modeling Particulate Syst Sydney NSW 2052 Australia

This paper presents a study of the structural transition of the packing of uniform spheres with a wide range of packing fractions. Several critical states are identified including the onset of local jamming, onset of global jamming and maximally random jammed (MRJ) states. With the increase of packing fraction rho, the packing structure transforms from one-dimensional chains to two-dimensional triangles and finally three-dimensional tetrahedra, correspondingly undergoing phase changes from non-jamming to local jamming, global jamming, MRJ and. nally crystal structure. There is a competition between FCC (face-centred cubic) and HCP (hexagonal closed packed) in the transition from disordered to ordered structure with the increase of rho. HCP can transform to FCC after reaching its maximum at rho = 0.7. Copyright (C) EPLA, 2009

关键词： Disordered solids Powders, porous materials structural modeling: serial-addition models, computer simulation

来源：评论

学校读者我要写书评

暂无评论

Influence of the temperature on the structure of an amorphous Ni₄₆Ti₅₄ alloy produced by mechanical alloying

引用

EUROPEAN PHYSICAL JOURNAL B 2008年第2期64卷 201-209页

作者： Gasperini, A. A. M. Machado, K. D. Buchner, S. de Lima, J. C. Grandi, T. A. Univ Estadual Campinas Inst Fis Gleb Wataghin BR-13083970 Campinas SP Brazil Univ Fed Parana Dept Fis Ctr Politecn BR-81531990 Curitiba Parana Brazil Univ Fed Santa Catarina Dept Fis BR-88040900 Florianopolis SC Brazil

The evolution of the local atomic order of an amorphous Ni46Ti54 alloy produced by mechanical alloying as a function of temperature was studied by synchrotron X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. XRD measurements at several temperatures (25 degrees C, 350 degrees C, 412 degrees C, 430 degrees C, 450 degrees C and 515 degrees C) were performed and analyzed using the reverse Monte Carlo (RMC) simulations method or the Rietveld refinement procedure. The experimental total structure factor for samples at 25 degrees C and 350 degrees C, which are amorphous in nature, were simulated by using the RMC method, and the local structures of the alloy at both temperatures were determined, indicating a decrease in its density as the temperature increases. At 412 degrees C, the XRD pattern shows a partially crystalline sample, indicating that the crystallization process is in progress. At 430 degrees C, 450 degrees C and 515 degrees C, the XRD measurements indicate the presence of two crystalline phases, NiTi and NiTi2, whose structural parameters (lattice parameters, coherently diffracting domains (CDD) sizes, microstrains and relative amount of phases) were determined using the Rietveld refinement procedure. DSC measurements at different heating rates furnished the crystallization temperature, enthalpy and activation energy of the crystallization process, and these values are similar to those found in other amorphous alloys of the Ni-Ti system. They also showed the existence of a second exothermic process, which was related to diffusive processes in the crystalline phases, which could be associated with the changes in the CDD sizes happening from 450 degrees C to 515 degrees C.

关键词： Amorphous semiconductors, metals, and alloys Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation structural modeling: serial-addition models, computer simulation Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.

来源：评论

学校读者我要写书评

暂无评论

structural properties of amorphous Fe₂O₃ nanoparticles

引用

EUROPEAN PHYSICAL JOURNAL D 2008年第3期49卷 325-332页

作者： Khanh, B. T. H. L. Hoang, V. V. Zung, H. HochiMinh City Natl Univ Coll Nat Sci Dept Phys Comp Phys Lab Ho Chi Minh City Vietnam HochiMinh City Natl Univ Inst Technol Dept Phys Ho Chi Minh City Vietnam HochiMinh City Natl Univ Dept Sci & Technol Ho Chi Minh City Vietnam

We have investigated the microstructure of amorphous Fe2O3 nanoparticles by using molecular dynamics (MD) simulations. Non-periodic boundary conditions with Born-Mayer type pair potentials were used to simulate a spherical model of different diameters of 2, 3, 4 and 5 nm. structural properties of an amorphous model obtained at 350 K have been analyzed in detail through the partial radial distribution functions (PRPFs), coordination number distributions, bond-angle distributions and interatomic distances. Calculations showed that structural characteristics of the model are in qualitative agreement with the experimental data. The observation of a large amount of structural defects as the particle size is decreased suggested that surface structure strongly depends on the size of nanoparticles. In addition, surface structure of amorphous Fe2O3 nanoparticles have been studied and compared with that observed in the core and in the bulk counterpart. Radial density profiles and stoichiometry in morphous Fe2O3 nanoparticles were also found and discussed.

关键词： Structure of nanoscale materials Amorphous materials, glasses and other disordered solids structural modeling: serial-addition models, computer simulation

来源：评论

学校读者我要写书评

暂无评论

Can a difference in molecular weights cause an eruption in a driven flow of self-organizing immiscible system?

引用

EUROPEAN PHYSICAL JOURNAL B 2008年第1期61卷 83-88页

作者： Pandey, R. B. Gettrust, J. F. USN Res Lab Stennis Space Ctr MS 39529 USA Univ So Mississippi Dept Phys & Astron Hattiesburg MS 39406 USA

Driven flow of a non-equilibrium non-conservative (NENC) system with a mixture of immiscible particles (A,B of molecular weight M-A, M-B) exhibits self-organizing patterns (segregation, phase-separation, etc.) in steady-state. The flow response (v) of mass flux density (j) to bias (H), v = partial derivative j/partial derivative H in steady-state is found to be sensitive to molecular weight ratio (alpha = M-B/M-A). While the flux density (j) responds linearly to bias for both components (A, B) at alpha = 1, onset of eruptive response occurs at extreme bias (H -> 1) at alpha > 1 where v -> infinity for heavier (B) and v -> -infinity for lighter (A) constituents. Difference in molecular weights (M-A, M-B) is not only critical to eruptive flow but also in controlling the flow response prior to this crossover.

关键词： structural modeling: serial-addition models, computer simulation computer simulation of molecular and particle dynamics

来源：评论

学校读者我要写书评

暂无评论

simulation studies of soft matter: generic statistical properties and chemical details

引用

EUROPEAN PHYSICAL JOURNAL B 2008年第3-4期64卷 525-529页

作者： Kremer, K. Max Planck Inst Polymer Res D-55128 Mainz Germany

The relation between atomistic structure, architecture, molecular weight and material properties is a basic concern of modern soft material science. This by now goes far beyond standard properties of bulk materials. A typical additional focus is on surface or interface aspects or on the relation between structure and function in nanoscopic molecular assemblies. This all implies a thorough understanding on many length and correspondingly time scales ranging from (sub)-atomic to macroscopic. At this point computer simulations are playing an increasingly important, if not the central role. Traditionally simulations have been separated in two main groups, namely simplified models to deal with generic or universal aspects of polymers, i.e. critical exponents, and those employing classical force field simulations with (almost) all atomistic detail, i.e. for the diffusion of small additives in a small "sample". Still characteristic problems, which require huge systems and/or long times in combination with a chemistry specific model, cannot be tackled by these methods alone. More recently with the development of scale bridging or multi scale simulation techniques, these different approaches have been combined into an emerging rather powerful tool. It is the purpose of this contribution to give a few examples of how such an approach can be used to understand specific material properties.

关键词： structural modeling: serial-addition models, computer simulation computer simulation of molecular and particle dynamics

来源：评论

学校读者我要写书评

暂无评论

Reply to the comment by I. I. Buchinskaya and P. P. Fedorov

引用

EPL 2008年第1期83卷

作者： Picinin, A. Silva, M. A. P. Rino, J. P. USP Inst Fis Sao Carlos BR-13560970 Sao Carlos SP Brazil Campus Univ Mat UFJF Dept Quim BR-36036900 Juiz De Fora MG Brazil Univ Fed Sao Carlos Dept Fis BR-13565905 Sao Carlos SP Brazil

FullText for HTML: https://***/10.1209/0295-5075/83/16002

关键词： structural modeling: serial-addition models, computer simulation Thermal properties of crystalline solids Diffusion in solids

来源：评论

学校读者我要写书评

暂无评论

Comment on "The eutectic composition on Cd_xPb_1-xF₂ phase diagram:: A molecular-dynamics study" by !Picinin A., !Silva M. A. P., !Rino J. P., and !Hai G. Q.

引用

EPL 2008年第1期83卷

作者： Buchinskaya, I. I. Fedorov, P. P. Russian Acad Sci Inst Crystallog Moscow 119333 Russia Russian Acad Sci Inst Gen Phys Moscow 119991 Russia

FullText for HTML: https://***/10.1209/0295-5075/83/16001

关键词： structural modeling: serial-addition models, computer simulation Thermal properties of crystalline solids Diffusion in solids

来源：评论

学校读者我要写书评

暂无评论

structural properties of amorphous TiO₂ nanoparticles

引用

EUROPEAN PHYSICAL JOURNAL D 2007年第3期44卷 515-524页

作者： Hoang, V. V. Zung, H. Trong, N. H. B. Natl Univ Hochiminh City Inst Technol Dept Phys Ho Chi Minh City Vietnam Natl Univ Hochiminh City Dept Sci & Technol Ho Chi Minh City Vietnam Natl Univ Hochiminh City Coll Nat Sci Dept Mat Sci Ho Chi Minh City Vietnam

structural properties of amorphous TiO2 spherical nanoparticles have been studied in models with different sizes of 2 nm, 3 nm, 4 nm and 5 nm under non-periodic boundary conditions. We use the pairwise interatomic potentials proposed by Matsui and Akaogi. models have been obtained by cooling from the melt via molecular dynamics (MD) simulation. structural properties of an amorphous nanoparticle obtained at 350 K have been analyzed in detail through the partial radial distribution functions (PRDFs), coordination number distributions, bond-angle distributions and interatomic distances. Moreover, we show the radial density profile in a nanoparticle. Calculations show that size effects on structure of a model are significant and that if the size is larger than 3 nm, amorphous TiO2 nanoparticles have a distorted octahedral network structure with the mean coordination number Z(Ti-O) approximate to 6.0 and Z(O-Ti) approximate to 3.0 like those observed in the bulk. Surface structure and surface energy of nanoparticles have been obtained and presented.

关键词： Nanoscale materials computer simulation of liquid structure Amorphous materials, glasses and other disordered solids structural modeling: serial-addition models, computer simulation

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：