Electronic, mechanical and piezoelectric properties of glass-like complex Na 2 Si 1- x Ge x O 3 ( x = 0.0, 0.25, 0.50, 0.75, 1.0).

Motivated by our previous work on pristine Na 2 SiO 3 , we proceeded with calculations on the structural, electronic, mechanical and piezoelectric properties of complex glass-like Na 2 Si 1- x Ge x O 3 ( x = 0.0, 0.25, 0.50, 0.75, 1.0) by using density functional theory (DFT). Interestingly, the optimized bond lengths and bond angles of Na 2 SiO 3 and Na 2 GeO 3 resemble each other with high similarity. On doping we report the negative formation energy and feasibility of transition of Na 2 SiO 3 → Na 2 GeO 3 while the structural symmetry is preserved. Analyzing the electronic profile, we have observed a reduced band gap on increasing x = Ge concentration at Si-sites. All the systems are indirect band gap ( Z - Γ ) semiconductors. The studied systems have shown mechanical stabilities by satisfying the Born criteria for mechanical stability. The calculated results have shown highly anisotropic behaviour and high melting temperature, which are a signature of glass materials. The piezoelectric tensor (both direct and converse) is computed. The results thus obtained predict that the systems under investigation are potential piezoelectric materials for energy harvesting.