Please use this identifier to cite or link to this item: http://ktisis.cut.ac.cy/handle/10488/7694
Title: Structural properties and energetics of amorphous forms of carbon
Authors: Kelires, Pantelis C. 
Keywords: Carbon;Monte Carlo method;Density
Issue Date: 1993
Publisher: APS American Physical Society
Source: Physical Review B,1993, Volume 47, Issue 4, Pages 1829-1839
Abstract: We have made a comparative theoretical study of the most common forms of unhydrogenated amorphous carbon (α-C), namely, of the dense, diamondlike phase and the low-density evaporated α-C (e-C). Emphasis is given to the connection among the structure, energetics, and stability of these phases. To make the simulations of the amorphous structures (formed by quenching the liquid) tractable, we used the Monte Carlo method, combined with the empirical-potential approach. Our analysis employs a powerful total-energy-partitioning scheme, which is proved very useful in treating the energetics of disordered systems. It is found that threefold sp2 sites are the energetically favorable geometries in e-C, and thus they are by far more numerous. The nonplanar character of sp2 sites and the absence of sixfold rings indicate that medium-range order is rather not significant in e-C. The increasing graphitic character of e-C, as the temperature is raised, is explained by resorting to the effective temperatures T*, at which the atoms freeze in their lattice positions. For diamondlike α-C, the simulations show that there exist two distinctly different dense structures. The ''as-quenched'' one (i-C) is mostly sp3 bonded, but it is metastable. Upon annealing, it converts into a second phase (i-C*), mostly sp2 bonded, with a significant energy gain. A specific mechanism is proposed for this transition. The insensitivity of density to annealing is explained if we use the concept of the ''glass transition temperature'' T*. Finally, by introducing an isotropic bulk modulus for the amorphous phase, it is found that e-C has a much lower compressibility than i-C*, enhancing the distinguishability among the two low-coordinated forms of α-C.
URI: http://ktisis.cut.ac.cy/handle/10488/7694
ISSN: 0163-1829
DOI: 10.1103/PhysRevB.47.1829
Rights: © 1993 The American Physical Society.
Type: Article
Appears in Collections:Άρθρα/Articles

Show full item record

SCOPUSTM   
Citations 5

78
checked on Nov 16, 2017

WEB OF SCIENCETM
Citations 5

79
Last Week
0
Last month
0
checked on Nov 23, 2017

Page view(s)

23
Last Week
0
Last month
1
checked on Nov 24, 2017

Google ScholarTM

Check

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.