Comparison and analysis of properties of transparent and translucent diamonds prepared via DC arc plasma jet CVD

• Published in: Diamond and related materials Vol. 142; p. 110710
• Main Authors: Shao, Siwu, Liu, Peng, Ye, Sheng, Chen, Liangxian, Zhang, Jianjun, Wei, Junjun, Liu, Jinlong, Li, Chengming
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2024
• Subjects: DC arc plasma jet chemical vapor deposition; Diamond defects study; High deposition rate; Optical and thermal grade diamond films; X-ray CT; High deposition rate; X-ray CT; Optical and thermal grade diamond films; DC arc plasma jet chemical vapor deposition; Diamond defects study
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2023.110710

The direct-current arc plasma jet method is advantageous for the rapid deposition of large-area self-supporting diamond films. However, dark defects tend to be generated during the growth process, significantly affecting the performance of the diamond. In this study, we use the direct-current arc plasma jet method to prepare transparent and translucent samples. Subsequently, we compare their optical, thermal, and mechanical properties and analyze the differences in their performances via microstructure and defect analyses. The results indicate that the transparent diamond samples exhibit excellent optical and thermal properties, with a transmittance of 68.4 % at a wavelength of 10.6 μm and a thermal conductivity similar to that of type-IIa single crystal diamond (i.e. 2002 W/(m·K)). Meanwhile, the translucent diamond exhibits outstanding mechanical properties, with a fracture strength of 984 MPa. Characterization results based on electron backscatter diffraction and X-ray computed tomography suggest that a preferred orientation along the (220) planes is conducive to the densification growth of the samples, thereby enhancing their optical and thermal properties. However, the generation of numerous twins results in interlocking between grains, which improves sample's mechanical properties but introduces porosity and impurities, thus deteriorating its optical and thermal performance. [Display omitted] •Optical and thermal diamond films were deposited by DC-arc plasma jet CVD with growth rates >6 μm/h.•Strong (220) texture and numerous twins can improve optical transmittance and fracture strength, respectively.•X-ray CT was used to reveal defects distribution and content within diamond samples.