Structural, bonding, anisotropic mechanical and thermal properties of Al4SiC4 and Al4Si2C5 by first-principles investigations. Issue 3 (1st September 2016)

• Record Type: Journal Article
• Authors: Sun, Liang; Gao, Yimin; Li, Yefei; Yoshida, Katsumi; Yano, Toyohiko; Yi, Dawei
• Is Part Of: Journal of Asian ceramic societies. Volume 4:Issue 3(2016)
• Page Start: 289
• Page End: 298
• Publication Date: 2016-09-01
• Subjects: Bond length -- Anisotropy -- Heat capacity; Ceramics -- East Asia -- Periodicals; Materials science -- Periodicals; 620.1405
• DOI: 10.1016/j.jascer.2016.05.006
• Languages: English
• ISSNs: 2187-0764

Abstract

Abstract: The structural, bonding, electronic, mechanical and thermal properties of ternary aluminum silicon carbides Al4 SiC4 and Al4 Si2 C5 are investigated by first-principles calculations combined with the Debye quasi-harmonic approximation. All the calculated mechanical constants like bulk, shear and Young's modulus are in good agreement with experimental values. Both compounds show distinct anisotropic elastic properties along different crystalline directions, and the intrinsic brittleness of both compounds is also confirmed. The elastic anisotropy of both aluminum silicon carbides originates from their bonding structures. The calculated band gap is obtained as 1.12 and 1.04 eV for Al4 SiC4 and Al4 Si2 C5 respectively. From the total electron density distribution map, the obvious covalent bonds exist between Al and C atoms. A distinct electron density deficiency sits between Al–C bond along c axis among Al4 SiC4, which leads to its limited tensile strength. Meanwhile, the anisotropy of acoustic velocities for both compounds is also calculated and discussed.