STUDY OF THE STRAIN ANISOTROPY AND BOND STIFFNESS OF HIGH-DENSITY CARBON MATERIALS: DIAMOND AND Pn-C10
Year: 2024
Type: article
Abstract: Experimental data indicate that it is possible to obtain materials superior to diamond in hardness, such as ultra-hard fullerites and nanodiamonds. However, these data are at odds with theoretical predictions. Careful calculations have failed to find structures exhibiting mechanical properties comparable to those experimentally obtained. A possible reason is the local nature of carbon ultrahigh hardness associated with the formation of regions with chemical bonds of increased rigidity. Such regions are expected to be characterized by a higher density of the material, consistent with the data on obtaining superhard carbon phases with a density exceeding that of diamond. Theoretical calculations confirm the possibility of existence of denser phases than diamond. However, their elastic moduli do not exceed the corresponding values for diamond. The modulus of elasticity is not an ideal characteristic for materials with inhomogeneous stiffness. A more appropriate characteristic in such cases is the average bond stiffness. In this work, the relationship between bulk modulus of elasticity and average bond stiffness was investigated for two high-density carbon crystals: diamond and Pn-C10. We were interested in the reason why Pn-C10 shows lower values of bulk modulus despite its higher density. Such anisotropic deformation of Pn-C10 under isotropic compression, unlike diamond, is manifested due to the presence in the crystal structure of two different bonds of 1.51 Å (short and more “rigid”) and 1.65 Å (long and more “soft”). Longer bonds are subject to significantly greater deformation, which ultimately leads to higher anisotropy and, consequently, to a lower bulk modulus of elasticity for Pn-C10. For citation: Zhukov V.V., Sorokin P.B. Study of the strain anisotropy and bond stiffness of high-density carbon materials: diamond and Pn-C10. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 10. P. 16-21. DOI: 10.6060/ivkkt.20246710.9y.
Authors: Vladlen V. Zhukov, Pavel B. Sorokin
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4403490318