Volume 87, Number 5, September 2009
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||23 September 2009|
Phase stabilities and mechanical properties of two new carbon crystals
College of Engineering Science and Technology, Shanghai Ocean University - Shanghai 201306, China
2 State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences - Shanghai 200050, China
Corresponding author: email@example.com
Accepted: 24 August 2009
Density functional calculations are used to systematically evaluate phase stabilities and mechanical properties of two recently proposed carbon crystals (K4 and M-carbon), along with graphite, cubic diamond and hexagonal diamond. It is found that the K4 carbon, which can be referred to as a twin of the cubic diamond crystal, is mechanically unstable, implying that it cannot be formed. Remarkably, our calculations not only substantiate the M-carbon phase is a highly incompressible and potentially superhard material but also show that it exhibits mechanical stability. Moreover, a surprisingly small activation barrier (about 0.018 eV/atom) for the transformation of M-carbon to graphite explains some paradoxical experimental observations.
PACS: 64.60.My – Metastable phases / 64.10.+h – General theory of equations of state and phase equilibria / 62.20.-x – Mechanical properties of solids
© EPLA, 2009
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