Size dependence and orientation dependence of elastic properties of ZnO nanofilms

被引:28
作者
Cao, Guoxin [1 ]
Chen, Xi [1 ]
机构
[1] Columbia Univ, Dept Civil Engn & Engn Mech, Columbia Nanomech Res Ctr, New York, NY 10027 USA
基金
美国国家科学基金会;
关键词
size effect; molecular mechanics; elastic property;
D O I
10.1016/j.ijsolstr.2007.10.019
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
The elastic properties of ZnO nanofilms with different film thickness, surface orientations and loading directions are investigated by using molecular mechanics (MM) method. The size dependence of elastic properties is relevant to both the film surface crystallographic orientation and loading direction. Both atomic structure analysis and energy calculation are employed to identify the mechanisms of the size-dependent elastic properties, under different loading directions and surface orientations. Upon small axial deformation, the relationship between intralayer and interlayer bond length variation and film elastic stiffness is established; it is found that the atomic layers with larger bond length variation have higher elastic stiffness. The strain energies of atomic layers of ZnO nanofilm and bulk are decoupled, from which the stiffness of film surface, intralayers, and interlayers are derived and compared with their bulk counterparts. The surface stiffness is found to be much lower than that of the interior layers and bulk counterpart, and with the decrease of film thickness, the residual tension-stiffened interior atomic layers are the main contributions of the increased elastic modulus of ZnO nanofilms. (c) 2007 Elsevier Ltd. All rights reserved.
引用
收藏
页码:1730 / 1753
页数:24
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