Herein, we investigate the structural, electronic and mechanical properties of zigzag graphene nanoribbons in the presence of stress by applying density functional theory within the GGA-PBE (generalized gradient approximation-Perdew-Burke-Ernzerhof) approximation. The uniaxial stress is applied along the periodic direction, allowing a unitary deformation in the range of ± 0.02%. The mechanical properties show a linear response within that range while a nonlinear dependence is found for higher strain. The most relevant results indicate that Young's modulus is considerable higher than those determined for graphene and carbon nanotubes. The geometrical reconstruction of the C-C bonds at the edges hardens the nanostructure. The features of the electronic structure are not sensitive to strain in this linear elastic regime, suggesting the potential for using carbon nanostructures in nano-electronic devices in the near future.
We present an ab initio study on the structural and electronic distortions of modified graphene by creation of vacancies, inclusion of boron atoms, and the coexistence of both, by means of thermodynamics and band structure calculations. In the case of coexistence of boron atoms and vacancy, the modified graphene presents spin polarization only when B atoms locate far from vacancy. Thus, when a boron atom fills single-and di-vacancies, it suppresses the spin polarization of the charge density. In particular when B atoms fill a
Fullerene-Like (FL) sulpho-carbide (CS x ) compounds have been addressed by first principles calculations. Geometry optimization and cohesive energy results are presented for the relative stability of precursor species such as C 2 S, CS 2 , and C 2 S 2 in isolated form.The energy cost for structural defects, arising from the substitution of C by S is also reported. Similar to previously synthesized FL-CN x and FL-CP x compounds, the pentagon, the double pentagon defects as well as the Stone-Wales defects are confirmed as energetically feasible in CS x compounds.
atmosphere. The fluorine content of the films was controlled by varying the CF 4 partial pressure from 0 mPa to 110 mPa at a constant deposition pressure of 400 mPa and a substrate temperature of 110 ºC. The films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by applying elastic recoil detection analysis, Xray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and nanoindentation. First-principles calculations were carried out to predict and explain Fcontaining carbon thin film synthesis and properties. By geometry optimizations and cohesive energy calculations the relative stability of precursor species including C 2 , F 2 and radicals, resulting from dissociation of CF 4 , were established. Furthermore, structural defects, arising from the incorporation of F atoms in a graphene-like network, were evaluated. All as-deposited CF x films are amorphous. Results from X-ray photoelectron spectroscopy and Raman spectroscopy indicate a graphitic nature of CF x films with x ≤ 0.23 and a polymeric structure for films with x 0.26. Nanoindentation reveals hardnesses between ~1 GPa and ~16 GPa and an elastic recovery of up to 98 %.
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