Temperature and defect effects on the mechanical properties of pentadiamond

HS Qin and GQ Zhang and YY Zhang and L Qin and YL Liu and QX Pei, DIAMOND AND RELATED MATERIALS, 118, 108523 (2021).

DOI: 10.1016/j.diamond.2021.108523

Pentadiamond is a newly predicted 3D carbon allotrope by first- principles calculations. Using molecular dynamics simulations, we show that pentadiamond can keep structure stable at high temperatures up to 1100 K, but its fracture strength and fracture strain are very sensitive to temperature. As the temperature increases from 100 K to 900 K, the fracture strength and fracture strain decreases by 68.4% and 69.1%, respectively. We also find that the mono-vacancy and di-vacancy related to C2 position lead to stronger reduction in the fracture strength and fracture strain than the atomic vacancies at other positions. To be surprising, the mono-vacancy at C2 position has stronger effect than the di-vacancy at C2-C3 positions. Besides, we find that hydrogen functionalization has strong effect on the mechanical properties of pentadiamond. As the H-coverage increases from 0.0 to 1.0, the fracture strength and fracture strain drop by 75.7% and 76.6%, respectively. Our work provides valuable insights into the mechanical behaviors of this new material.

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