Mechanical properties of ultrananocrystalline diamond prepared in a nitrogen-rich plasma: A theoretical study

Jeffrey T. Paci, Ted Belytschko, George C Schatz

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We examine the mechanical properties of ultrananocrystalline diamond (UNCD) produced by plasma-enhanced chemical vapor deposition, with a focus on thin films created with high levels of nitrogen in the plasma. A model with several of the attributes of the corresponding experimental UNCD is developed and its properties explored. Simulations are performed using semiempirical quantum mechanics and density functional theory. Our results predict a Young's modulus of 0.69 TPa, failure strain of 0.13, and a tensile fracture stress of 61 GPa which are 66%, 100%, and 61%, respectively, of those predicted for UNCD produced in the absence of nitrogen. As in the case of UNCD produced without nitrogen in the plasma deposition, the fracture stress (σf =61 GPa) is very large compared to that observed experimentally; these indicate that the experimental specimens contain large defects and some estimates are made of the size of these defects using the Griffith formula with the surface energy computed here. The effect of nitrogen on the mechanical properties of atom-wide UNCD grain boundaries is also investigated. Throughout, the accuracy of the various simulation methods is compared and evaluated.

Original languageEnglish
Article number184112
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number18
DOIs
Publication statusPublished - 2006

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Diamond
nitrogen plasma
Diamonds
Nitrogen
diamonds
mechanical properties
Plasmas
Mechanical properties
nitrogen
Plasma deposition
Defects
Quantum theory
defects
Plasma enhanced chemical vapor deposition
Interfacial energy
surface energy
Density functional theory
quantum mechanics
modulus of elasticity
Grain boundaries

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Mechanical properties of ultrananocrystalline diamond prepared in a nitrogen-rich plasma : A theoretical study. / Paci, Jeffrey T.; Belytschko, Ted; Schatz, George C.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 74, No. 18, 184112, 2006.

Research output: Contribution to journalArticle

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