Please use this identifier to cite or link to this item:
https://hdl.handle.net/20.500.14279/1379
Title: | Structural properties and energetics of amorphous forms of carbon | Authors: | Kelires, Pantelis C. | Major Field of Science: | Engineering and Technology | Field Category: | Mechanical Engineering | Keywords: | Carbon;Monte Carlo method;Density | Issue Date: | 1993 | Source: | Physical Review B,1993, vol. 47, no. 4, pp. 1829-1839 | Volume: | 47 | Issue: | 4 | Start page: | 1829 | End page: | 1839 | Journal: | Physical Review B | 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: | https://hdl.handle.net/20.500.14279/1379 | ISSN: | 01631829 | DOI: | 10.1103/PhysRevB.47.1829 | Rights: | © American Physical Society | Type: | Article | Affiliation : | University of Crete Research Center of Crete |
Publication Type: | Peer Reviewed |
Appears in Collections: | Άρθρα/Articles |
CORE Recommender
SCOPUSTM
Citations
86
checked on Nov 9, 2023
WEB OF SCIENCETM
Citations
50
81
Last Week
0
0
Last month
0
0
checked on Oct 29, 2023
Page view(s)
470
Last Week
1
1
Last month
5
5
checked on Aug 29, 2024
Google ScholarTM
Check
Altmetric
Items in KTISIS are protected by copyright, with all rights reserved, unless otherwise indicated.