摘要
The microstructural variation near surface of nano elastic materials is analyzed based on different potentials. The atomic/molecular mechanism underlying the variation and its effect on elastic modulus are such that the nature of long-range interactions （attractive or repulsive） in the atomic/molecular potentials essentially governs the variation near surface （looser or tighter） and results in two opposite size effects （decreasing or increasing modulus） with decreasing size.
The microstructural variation near surface of nano elastic materials is analyzed based on different potentials. The atomic/molecular mechanism underlying the variation and its effect on elastic modulus are such that the nature of long-range interactions （attractive or repulsive） in the atomic/molecular potentials essentially governs the variation near surface （looser or tighter） and results in two opposite size effects （decreasing or increasing modulus） with decreasing size.
基金
Supported by the National Natural Science Foundation of China under Grant Nos 10721202, 10432050, 10772012 and 10732090, and the Knowledge Innovation Project of Chinese Academy of Sciences （KJCX2-YW-M04）.
