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arXiv 0801.0407cond-mat.mtrl-scicond-mat.mes-hall
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低维材料的热力学行为

The thermo-mechanical behavior of low-dimensional materials

Chang Q Sun

摘要:

低维系统包括单原子链、空心管、表面皮、纳米腔、纳米线和纳米颗粒,对这些有趣行为背后的机制的一致性原子理解长期以来一直是一个很大的挑战。本文报道了这方面的最新进展。一项调查,然后是分析方法,从键合能的角度来看,其功能依赖于外部刺激的协调环境和温度变化的本地键平均(LBA)。它示出的可测量的量的一个标本可以功能相关的代表性债券的身份和他们对外界刺激的反应。应当理解,欠配位原子之间的缩短和加强的键以及相关的局部应变和能量捕获本质上决定了具有大部分欠配位原子的系统的机械行为。物质的热软化是由热致键膨胀和晶格振动引起的,晶格振动通过内能增加来削弱键。松弛表面皮中的能量密度增益与剩余原子内聚能之间的竞争决定了介观试样的力学性能,而原子位错的激活与抑制之间的竞争则决定了试样在塑性形变中的屈服强度。

英文摘要:

Consistently atomistic understanding of the mechanism behind the intriguing behavior of low-dimensional systems including monatomic chains, hollow tubes, surface skins, nanocavities, nanowires, and nanograins has long been a high challenge. This article reports recent progress in this regard. A survey is presented and then is followed by analytical approaches in terms of local bond average (LBA) from the perspective of bonding energetics and its functional dependence on external stimuli of coordination environment and temperature change. It is shown that the measurable quantities of a specimen can be functionally correlated to the identities of the representative bonds and their responses to the external stimuli. It is understood that the shortened and strengthened bonds between the under-coordinated atoms and the associated local strain and energy trapping dictate intrinsically the mechanical behavior of systems with large portion of under-coordinated atoms. The thermal softening of a substance arises from thermally-induced bond expansion and lattice vibration that weakens the bonds through the internal energy increase. The competition between the energy-density-gain and the residual atomic cohesive-energy in the relaxed surface skin determines intrinsically the mechanical performance of a mesoscopic specimen, whereas competition between the activation and inhibition of atomic dislocations dominates extrinsically the yield strength of the specimen in plastic deformation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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