| ZHANG Er-geng,NIU Shuai,CHEN Qiang,PAN Wen-gao,LI Chao-yang.First-principles on Stress Reduction Mechanism of Copper Doped Diamond-like Carbon Films[J],49(2):295-300 |
| First-principles on Stress Reduction Mechanism of Copper Doped Diamond-like Carbon Films |
| Received:June 17, 2019 Revised:February 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.02.037 |
| KeyWord:Cu-DLC first principle stress reduction radial distribution function residual stress bond length bond angle |
| Author | Institution |
| ZHANG Er-geng |
1.Shanghai Engineering Research Center of Physical Vapor Deposition PVD Superhard Coating and Equipment, Shanghai Institute of Technology, Shanghai , China |
| NIU Shuai |
1.Shanghai Engineering Research Center of Physical Vapor Deposition PVD Superhard Coating and Equipment, Shanghai Institute of Technology, Shanghai , China |
| CHEN Qiang |
1.Shanghai Engineering Research Center of Physical Vapor Deposition PVD Superhard Coating and Equipment, Shanghai Institute of Technology, Shanghai , China |
| PAN Wen-gao |
2.Shanghai Liyuan Environmental Technology Limited Company, Shanghai , China |
| LI Chao-yang |
2.Shanghai Liyuan Environmental Technology Limited Company, Shanghai , China |
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| Abstract: |
| The work aims to compare the evolution laws in the properties of diamond-like carbon films doped with different concentrations of copper and analyze the mechanism of the effects of copper doping on the properties of diamond-like carbon films. The initial models of copper-DLC doped with different concentrations of copper (1.56at.%~7.81at.%) and densities of 2.03 g/cm3 and 2.87 g/cm3 were established. The melting annealing and quenching processes were simulated by NVT and NOSE temperature regulation methods, and the geometric model was optimized by conjugate gradient method based on generalized gradient approximation (GGA). The radial distribution functions (RDF), sp3-C content, bulk modulus, bond length and bond angle distribution of the copper-DLC model were calculated by CASTEP and the effects of Cu doping on the stress change of DLC films were also discussed. The proportion of sp3-C hybridization increased with the increase of Cu content. Compared with DLC, the location of the first and second peaks in RDF of Cu-doped DLC shifted significantly. The residual stress in the films decreased first and then increased with the increase of the content of Cu. The residual stress was the smallest when the content of Cu was 1.56at.%(7.2 GPa). With the increase of Cu content, the peak value of the total bond angle distribution decreased, the peak width moved to the small bond angle, and the peak value of the total bond length distribution decreased, resulting in a small and wide peak in the long bond length direction. The weak bond properties of C—Cu and the relaxation of twisted bond angles and bond lengths have significant effects on the reduction of residual compressive stress. At higher concentration of Cu, the proportion of twisted C—C bonds increases, and more twisted C—Cu and Cu—Cu structures are formed, which is the key factor leading to the increase of residual stress. |
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