We propose a method to calculate the ideal shear strength τ of two surfaces in contact by ab initio calculations. This quantity and the work of adhesion γ are the interfacial parameters usually derived from tip-based friction force measurements. We consider diamond interfaces and quantitatively evaluate the effects of surface orientation and passivation. We find that in the case of fully passivated interfaces, γ is not affected by the orientation and the alignment of the surfaces in contact. On the contrary, τ does show a dependence on the atomic-scale roughness of the interface. The surface termination has a major impact on the tribological properties of diamond. The presence of dangling bonds, even at concentrations low enough to prevent the formation of interfacial C-C bonds, causes an increase in the resistance to sliding by 2 orders of magnitude with respect to the fully hydrogenated case. We discuss our findings in relation to experimental observations. © 2011 American Chemical Society.
Ab initio calculation of the adhesion and ideal shear strength of planar diamond interfaces with different atomic structure and hydrogen coverage / Zilibotti, Giovanna; Righi, Maria Clelia. - In: LANGMUIR. - ISSN 0743-7463. - 27:11(2011), pp. 6862-6867. [10.1021/la200783a]
Ab initio calculation of the adhesion and ideal shear strength of planar diamond interfaces with different atomic structure and hydrogen coverage
ZILIBOTTI, Giovanna;RIGHI, Maria Clelia
2011
Abstract
We propose a method to calculate the ideal shear strength τ of two surfaces in contact by ab initio calculations. This quantity and the work of adhesion γ are the interfacial parameters usually derived from tip-based friction force measurements. We consider diamond interfaces and quantitatively evaluate the effects of surface orientation and passivation. We find that in the case of fully passivated interfaces, γ is not affected by the orientation and the alignment of the surfaces in contact. On the contrary, τ does show a dependence on the atomic-scale roughness of the interface. The surface termination has a major impact on the tribological properties of diamond. The presence of dangling bonds, even at concentrations low enough to prevent the formation of interfacial C-C bonds, causes an increase in the resistance to sliding by 2 orders of magnitude with respect to the fully hydrogenated case. We discuss our findings in relation to experimental observations. © 2011 American Chemical Society.Pubblicazioni consigliate
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