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Five-parameter equation of state for solids correctly incorporating cohesive energy data

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Chinese Physics B 2011年第8期20卷 125-129页

作者：田荣刚孙久勋 Department of Applied Physics University of Electronic Science and Technology

A five-parameter equation of state （EOS） is proposed to correctly incorporate the cohesive energy data in it without physically incorrect oscillations. The proposed EOS is applied to 10 selected metals. It is shown that the calculated compression curves are in good accordance with the experimental data. The values of the bulk modulus and its derivative with respect to pressure extracted from the proposed EOS remain almost unchanged while the data range used is varied.

关键词： equation of state cohesive energy physically incorrect oscillations

First-principles investigation of cohesive energy and electronic structure in vanadium phosphides

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Journal of Central South University 2012年第7期19卷 1796-1801页

作者：杨振华王先友苏旭平 Faculty of Materials Optoelectronics and PhysicsXiangtan University Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education(Xiangtan University) School of Chemistry Xiangtan University Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education(Xiangtan University) Key Laboratory of Materials Design and Preparation Technology of Hunan Province(Xiangtan University)

First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions,and covalent bond exists between the V and P atoms of V3P,V2P,VP,VP2 and VP4.

关键词： first-principles calculations stability cohesive energy covalent bond

A Calculation Approach to Elastic Constants of Crystallines at High Pressure and Finite Temperature

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Chinese Physics Letters 2002年第9期19卷 1319-1321页

作者：向士凯经福谦等 LaboratoryforShockWaveandDetonationPhysicsResearch SouthwestInstituteofFluidPhysicsPOBox919-111Mianyang621900 LaboratoryforShockWaveandDetonationPhysicsResearch SouthwestInstituteofFluidPhysicsPOBo

Elastic constants of Na and Li metals are calculated successfully for temperatures up to 350K and pressures up to 30GPa using a scheme without involving any adjustable parameter. Elastic constants areassumed to depend only on an effective pair potential that is only determined by the average interatomic distance. Temperature has aneffect on elastic constants by way of charging the equilibrium. The elastic constants can be obtained by fitting the relationship betweentotal energy and strain tensor using the new set of lattice parameters obtained by calculating displacement of atoms at the finite temperatureand at a fixed pressure. The relationship between the effective pair potential and the interatomic distance is fitted by using a series ofdata of cohesive energy corresponding to lattice parameters.

关键词： strain tensor Finite REACTOR LATTICE PARAMETERS Temperature CONSTANT PRESSURE Pair potential lattice parameters cohesive energy Elastic constants high pressure

Characteristics and mechanism of abrasive wear for thermoplastic polymers

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Journal of University of Science and Technology Beijing 2003年第5期10卷 44-47页

作者： XianJia XiaomeiLing DepartmentofScienceandTechnology UniversityofScienceandTechnologyBeijingBeijing100083China DepartmentofAnalyticalChemistry SchoolofPharmaceuticalSciencePekingUniversityBeijing100083China

Abrasive wear characteristics of polyethylene, polystyrene,polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relativewear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and lowtemperature tempered steel 45 was used as a comparing material), and have a linear correlation withsquare roots of their cohesive energy densities. The coefficients of linear correlation is *** morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of thethermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing andfatiguing for the soft and tough ones.

关键词： polymer abrasive wear wear mechanism cohesive energy

Electronic structures and properties of Ti, Zr and Hf metals

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Journal of Central South University of Technology 2001年第2期8卷 83-88页

作者： XIE You qing,PENG Kun,YANG Xin xin (Department of Materials Science and Engineering, Central South University, Changsha 410083, China) Department of Materials Science and Engineering Central South University Changsha China

The electronic structures of pure Ti, Zr and Hf metals with hcp structure were determined by one atom (OA) theory. According to the electronic structures of these metals,their potential curves, cohesive energies, lattice constants, elasticities and the temperature dependence of linear thermal expansion coefficients were calculated. The electronic structures and characteristic properties of these metals with bcc and fcc structures and liquids were also studied. The results show that the electronic structures of Ti, Zr and Hf metals are respectively [Ar](3d n) 0.481 0 (3d c) 2.085 7 (4s c) 1.000 0 (4s f) 0.433 3 , [Kr](4d n) 0.396 8 (4d c) 2.142 8 (5s c) 1.262 0 (5s f) 0.198 4 , [Xe](5d n) 0.368 0 (5d c) 2.041 4 (6s c) 1.406 6 (6s f) 0.184 0 . It is explained why the pure Ti, Zr and Hf metals with hcp and bcc structures can exist naturally, while those with fcc structure can not.

关键词： electronic structure Ti Zr Hf lattice constant cohesive energy crystal structure

Kinetically-Induced Hexagonality in Chemically Grown Silicon Nanowires

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Nano Research 2009年第7期2卷 575-582页

作者： Xiaohua Liu Dunwei Wang Department of Chemistry Merkert Chemistry CenterBoston College2609 Beacon St.Chestnut HillMA 02467USA

Various silicon crystal structures with different atomic arrangements from that of diamond have been observed in chemically synthesized *** structures are typified by mixed stacking mismatches of closely packed Si *** of viewing them as defects,we define the concept of hexagonality and describe these structures as Si *** small transverse dimensions of a nanowire make this approach *** among the polymorphs are cubic symmetry diamond and hexagonal symmetry wurtzite *** diffraction studies conducted with Au as an internal reference unambiguously confirm the existence of the hexagonal symmetry Si *** energy calculations suggest that the wurtzite polymorph is the least stable and the diamond polymorph is the most *** energies of intermediate polymorphs follow a linear trend with respect to their structural *** identify the driving force in the polymorph formations as the growth *** longitudinal elongation during the growth freezes stacking mismatches and thus leads to a variety of Si *** results are expected to shed new light on the importance of growth kinetics in nanomaterial syntheses and may open up ways to produce structures that are uncommon in bulk materials.

关键词： Silicon nanowires hexagonality polytypes cohesive energy chemical vapor deposition kinetics

Electronic structure of Ag-Cu alloys

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Science China(Technological Sciences) 1998年第3期41卷 225-236页

作者：谢佑卿张晓东 Department of Materials Science and Engineering Central South University of TechnologyChangsha 410083China

According to the correlativity between energy, volume and electronic structure of characteristic crystals and bound conditions of OA theory, the Gibbs energy function, atomic volume function and electronic structure of Ag Cu alloys have been determined. Then the electronic structure and properties of disordered alloys with any composition and ordered alloys with any ordering degree can be calculated. The number of d c covalent electrons in the states of Ag characteristic atoms decreases with the increase of Cu atoms in the nearest neighbouring shell. The number of d c covalent electrons in the states of Cu characteristic atoms decreases with the increase of Ag atoms in the nearest neighbouring shell. Such changes lead to the tendencies of atomic segregation and partition into two phases in the Ag Cu system.

关键词： Ag-Cu alloys electronic structure atomic volume lattice constant cohesive energy

Relaxation of Small Molecules：an ab initio Study

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Communications in Theoretical Physics 2002年第5期37卷 597-600页

作者： CAOYi－Gang A.Antons 等 DepartmentofPhysics ZhejiangUniversityHangzhou310027China InstitutefurFestkorperforschung ForschungszentrumJulichD－52425JulichGermany

Using an ab initio total energy and force method, we have relaxed several group IV and group V elementalclusters, in detail the arsenic and antimony dimers, silicon, phosphorus, arsenic and antimony tetramers. The obtainedbond lengths and cohesive energies are more accurate than other calculating methods, and in excellent agreement withthe experimental results.

关键词： cluster cohesive energy EStCoMPP

Structures and Properties of Sc and Y Metals

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Journal of Central South University 2000年第3期12卷 136-139页

作者： PENG Kun,XIE You qing,PENG Hao,XU Ying hong (Department of Materials Science and Engineering, Central South University, Changsha 410083, China) Department of Materials Science and Engineering Central South University Changsha China

The electronic structures of pure Sc and Y metals with hcp structure have been determined by one atom (OA) theory, which are [Ar](3d c) 1.331 5 (4s c) 0.905 0 (4s f) 0.763 5 and [Kr](4d c) 1.293 0 (5s c) 0.947 0 (5s f) 0.760 0 . According to their electronic structure, their potential curves, cohesive energies, lattice constants, elasticity and the temperature dependence of linear thermal expansion coefficients have been calculated. The electronic structures and characteristic properties of these metals with bcc structures and primary liquids have also been studied, which has supplied the structural parameters and property parameters of Sc and Y with different crystal structures and also supplied a series of complete data for the theoretical design of Sc and Y based materials.

关键词： scandium yttrium electronic structure cohesive energy crystal structure