Designing new group IVA element and binary compounds based tetragonal-C5: First-principles calculations

The rich diversity of Group IVA Element (Si, Ge and Sn) and Group IVA- IVA compounds, with promising properties, have wide applications in various fields of modern industry. In this work, two wyckoff positions of T-C5 through elemental substitution with heavier group IVA elements, new T-X4Y, T-XY4 and T-Y5 have been designed and constructed. The structural stability and mechanical properties of through elemental substitution with heavier group IVA elements (Si, Ge, Sn) in T-C5 are calculated by first principles calculations based on the density functional theory such as elastic constants, mechanical moduli, Vickers hardness, mechanical anisotropyand lattice thermal conductivity. We found that T-C4Si, T-CSi4, T-Si5, T-Si4Ge, T-SiGe4, T-Si4Sn, T-SiSn4, T-Ge5, T-Ge4Sn, T-GeSn4 and T-Sn5 are dynamically and mechanically stable for X and Y atomic radius with smaller difference. The band gaps of new designed materials can be effectively tuned in the range 0.14-1.57 eV with HSE06 functional. In particular, T-Si5 is 1.57 eV with a direct band gap, T-Si4Ge and T-Si4Sn are an indirect band gap semiconductor of 1.29 and 1.23 eV with HSE06, respectively. The hardness of the new stable materials has been calculated using the semiempirical model. The designed new materials have smaller hardness because they have the larger ion property of through elemental substitution with heavier group IVA elements (Si, Ge, Sn) in T-C5. Furthermore, the lattice thermal conductivity is also estimated using PINK and other two empirical methods. The estimated values of the lattice thermal conductivity were found to be as low as 0.5 Wm −1 K −1 for T-GeSn4 and T-Sn5. The lattice thermal conductivity is substantially decreased from 298.76 (pristineT-C5) to 0.4 W m −1 K −1 (T-Sn5). • Through elemental substitution with heavier group IVA elements (Si, Ge and Sn) for T-C5 are dynamically and mechanically stable. • The some semiconductors have narrow band gaps with 0.14-1.57 eV which significantly improve the applications of semiconductors materials in red- and IR-light range. • The lattice thermal conductivity is substantially decreased of designed new materials. • As The atomic radius increases, the observed stiffness reduced of in T-X4Y, T-XY4 and T-Y5 (X,Y Si, Ge and Sn).