Pressure-induced physical properties of KNbO3 using first-principles calculations for photocatalytic application

Abstract

The current research work theoretically presents various pressure-induced physical properties of potassium niobate with a cubic structure of 2 × 2 × 2 optimized supercell. The employed exchange-correlation function is GGA with the PBE approach in the DFT-based CASTEP simulation tool. The noted bandgap exhibits a rising trend from 1.518 eV to 2.013 eV with an indirect semiconductor nature and this energy bandgap nature remains the same throughout under the external isotropic static pressure effect. The pressure-induced total and partial density of states were studied to confirm the degree of localized electrons in various bands. Moreover, according to Born stability criteria potassium niobate is found mechanically stable and possesses an anisotropic nature. It exhibits brittle nature at 0.00 GPa and 10 GPa whereas it is found ductile from 20 GPa to 100 GPa. It exhibits a super-hard nature from 0.0 to 30 GPa and an ultra-hard nature from 40 to 100 GPa. The Debye temperature and melting temperature increase as pressure rises. Furthermore, several optical features were examined under the effect of pressure, and it was observed that the optical curves slightly shifted toward higher energies with increasing pressure. The overall analysis exhibits that KNbO3 is a promising material for long-term photocatalytic activity.