The mechanical properties of single-crystal and ultrananocrystalline diamond: A theoretical study

Jeffrey T. Paci, Ted Belytschko, George C. Schatz

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We examine the mechanical properties of single-crystal and ultrananocrystalline diamond (UNCD) by simulating their fracture using semiempirical quantum mechanics and density functional theory. Our results predict a failure strain of 0.13 and a fracture stress of 100 GPa for UNCD, which are 37% and 43%, respectively, that of single-crystal diamond. The Young's modulus of UNCD is E = 1.05 TPa which is only slightly smaller than that of single-crystal diamond (E = 1.09 TPa). The UNCD fracture stress value (σf = 100 GPa) is very large compared to that observed experimentally (σf < 5 GPa). We use Griffith theory to show that this difference is due to defects in UNCD.

Original languageEnglish
Pages (from-to)351-358
Number of pages8
JournalChemical Physics Letters
Issue number4-6
Publication statusPublished - Oct 14 2005


ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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