Stress reduction behavior in metal-incorporated amorphous carbon films: first-principles approach

Abstract

Stress reduction behavior in metal-incorporated amorphous carbon films: first-principles approach Abstract. The stress reduction behavior in metal-incorporated amorphous carbon films was investigated by the first-principle calculation. We calculated the total energy of the system with changes in bond angles between the incorporated metal (Ti, Mo, Cr, W, Ag, Au, Al, Si, etc) and the carbon atoms by using DMOL 3 computational software package. The four carbon atoms are arranged as a tetrahedron, with a carbon or metal atom at the center. The total energy increased substantially as the bond angle deviated from the equilibrium value when a carbon atom is located at the tetrahedron center. However, with a replacement by a metal atom at the center of the tetrahedron, the increase in the total energy due to the distortion in bond angle was significantly reduced. The pivotal action of the metal atoms dissolved in the carbon matrix would be more significant when noble metals having filled d-shells are incorporated compared to the transition metals having unfilled d-shells. These atoms have a weak and more isotropic bond with carbon atoms as confirmed by the electron density distribution.

Structure, Mechanical and Tribological Properties of Me-Doped Diamond-Like Carbon (DLC) (Me = Al, Ti, or Nb) Hydrogenated Amorphous Carbon Coatings

“…Similar evolutions of internal stresses of the DLC coatings, as a function of the metal content, were also obtained by Dai and Wang for Al-DLC coatings [40], and by C. Corbella for Me-doped DLCs (W, Mo, Nb, and Ti) [45]. According to their model, Choi et al [63] suggest that the stress reduction in Me-DLC coatings is possible without significant deterioration of mechanical properties due to the pivotal role of the metal atoms; a distortion of the angle of the atomic bond may occur without a significant increase in elastic energy, which may be considered as resulting from weak and less directional Me-C bonds.…”

Effect of Cr Atom Plasma Emission Intensity on the Characteristics of Cr-DLC Films Deposited by Pulsed-DC Magnetron Sputtering

“…Therefore, the films possess a relatively lower internal stress when the set value increases up to 5%, which may improve the adhesion strength. Moreover, Choi et al pointed out that metal doping reduced the directionality of bond, which led to a decrease in internal stress caused by bond angle distortion in the amorphous carbon network [38]. However, plenty of carbide phases will be generated with further increases of the set value.…”

Advanced carbon hybrid materials

“…[45,47] Besides ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library hydrogenated a-C (a-C:H), various groups have also studied the structure of a-C with other impurities such as metals [91], nitrogen [92], fluorine [93] To complicate matters, a-C is also generally not uniform in its macrostructure. The irregularities could be intentionally build into the material through the manipulation of the ion energy during deposition or unintentionally create by deposition conditions.…”