A near-zero Poisson's ratio of Si with ordered nanopores. Issue 31 (21st July 2016)

• Record Type: Journal Article
• Authors: Yoo, Yongmin; Kim, Young-Joo; Kim, Do-Nyun; Lee, Joo-Hyoung
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 31(2016)
• Page Start: 21949
• Page End: 21953
• Publication Date: 2016-07-21
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp03248f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Significant reduction in the Poisson's ratio is predicted for Si with cylindrical nanopores through first-principles DFT calculations. Abstract : The Poisson's ratio ν ij = − ε res j / ε app i, where ε app i and ε res j ( i, j = x, y, z ) are applied and resulting strain, respectively, are computed from first-principles for Si with an array of cylindrical, nanometer-sized pores aligned in the z direction (nanoporous Si, or np-Si). Through density functional theory calculations, it is demonstrated that the periodic arrangement of pores introduces strong anisotropy in the Poisson's ratio of np-Si: while ν yz remains close to the Poisson's ratio of the bulk, ν zx and ν xy exhibit an increase and a sharp decrease from the bulk value, respectively, as the volume fraction of pores ( ϕ ) becomes large. It is shown that the characteristic dependence of the Poisson's ratio on ϕ originates from the difference in the actual stress on np-Si, which is caused by the dissimilar surface geometry. Unlike random porous materials, this finding signifies the importance of structural details in determining the mechanical response of ordered systems at a nanoscale.