Authentication email has already been sent, please check your email box: and activate it as soon as possible.
You can login to My Profile and manage your email alerts.
If you haven’t received the email, please:
|
|
There are 314 papers published in subject: > since this site started. |
Results per page: | 314 Total, 32 Pages | << First < Previous 29 30 31 32 |
Select Subject |
Select/Unselect all | For Selected Papers |
Saved Papers
Please enter a name for this paper to be shown in your personalized Saved Papers list
|
1. Thermal stability of bare and embedded nanostructures | |||
Sun Changqing | |||
Physics 17 June 2005 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:hermally stimulated process such as evaporation, phase transition, or solid-liquid transition of a solid consumes each a certain portion of the solid cohesive energy that is the sum of bond energy over all the coordinates of all the involved atoms. Generally, the critical temperatures for such processes drop with solid size, unless hetero capping or interfacial interaction becomes dominant, because of the increased portion of the lower-coordinated surface atoms [Sun et al., J. Phys. Chem. B108, 1080 (2004)]. It is intriguing, however, that the melting point (Tm) of a solid containing III-A or IV-A atoms oscillates with size (the Tm drops first and then rises as the solid size is reduced) and that the Tm of chemically capped nanosolid often increases with the inverse size. Here we show that bond nature evolution is essential for the selective nanosolids and at the junction interfaces, which is responsible for the superheating of the smallest nanosolids, chemically capped clusters, and | |||
TO cite this article:Sun Changqing. Thermal stability of bare and embedded nanostructures[OL].[17 June 2005] http://en.paper.edu.cn/en_releasepaper/content/2226 |
2. Size-induced acoustic hardening and optic softening of phonons in nanostructures | |||
Sun Changqing | |||
Physics 17 June 2005 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:t has been puzzling that the Raman optical modes shift to lower frequency (or termed as optical mode softening) associated with creation of Raman acoustic modes that shift to higher energy (or called as acoustic hardening) upon nanosolid formation and size reduction. Understandings of the mechanism behind the size-induced acoustic hardening and optic softening have been quite controversial. On the basis of the recent bond order-length-strength (BOLS) correlation [Phys. Rev. B 69 045105 (2004)], we show that the optical softening arises from atomic cohesive energy weakening of surface atoms and the acoustic mode hardening is predominated by intergrain interaction. Agreement between predictions and observations has been reached for Si, CdS, InP, TiO2, CeO2, and SnO2 nanostructures with elucidation of vibration frequency of the corresponding isolated dimers. Findings further evidence the impact of bond order loss to low-dimensional systems and the essentiality of the BOLS correlation in | |||
TO cite this article:Sun Changqing. Size-induced acoustic hardening and optic softening of phonons in nanostructures[OL].[17 June 2005] http://en.paper.edu.cn/en_releasepaper/content/2222 |
3. Mechanical strength of atomic chains, surface skins, and nanograins | |||
Sun Chang Qing | |||
Physics 14 June 2005 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:his report deals with the correlation between the mechanical strength and thermal stability of systems extending from monatomic chains to surface skins and solids over the whole range of sizes with emphasis on the significance of atomic coordination imperfection. Derived solutions show that a competition between the bond order loss and the associated bond strength gain of the lower coordinated atoms dictate the thermo-mechanics of the low dimensional systems. Bond order loss lowers the atomic cohesive energy that determines the temperature of melting (Tm), or the activation energy for atomic dislocation, whereas bond strength gain enhances the energy density, or mechanical strength, in the surface skin. Therefore, the surface is harder at T << Tm whereas the surface becomes softer when the T approaches the surface Tm that is lower than the bulk due to bond order loss. Hence, the strained nanostructures are usually stiffer at low T whereas the harder skins melt easier. Quantitative inf | |||
TO cite this article:Sun Chang Qing. Mechanical strength of atomic chains, surface skins, and nanograins[OL].[14 June 2005] http://en.paper.edu.cn/en_releasepaper/content/2200 |
4. Molecular-Dynamics Study of the influences of Si-doping upon | |||
Haiyang Song,Heming Sun | |||
Physics 27 May 2005 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:in this paper, a Si-doped armchaired single-walled carbon nanotube (SWCNT) (7, 7) and a perfect SWCNT (7, 7) are investigated using the classical molecular dynamics (MD) simulations method. The inter-atomic short-range interaction is represented by empirical Tersoff bond order potential. The computational results show that there is radius amplification in the Si-doped layer and the Young’s moduli of the Si-doped (7, 7) SWCNT is 1.015TPa and of the perfect (7, 7) SWCNT is 1.096 TPa, it is in good agreement with the existing experimental results. From our simulation, Si-doping decreases the Young’s modulus of SWCNT and with the increased strain levels, the effect of Si-doped layer in enhancing the local stress level increases. | |||
TO cite this article:Haiyang Song,Heming Sun. Molecular-Dynamics Study of the influences of Si-doping upon[OL].[27 May 2005] http://en.paper.edu.cn/en_releasepaper/content/2119 |
Select/Unselect all | For Selected Papers |
Saved Papers
Please enter a name for this paper to be shown in your personalized Saved Papers list
|
|
Results per page: | 314 Total, 32 Pages | << First < Previous 29 30 31 32 |
About Sciencepaper Online | Privacy Policy | Terms & Conditions | Contact Us
© 2003-2012 Sciencepaper Online. unless otherwise stated