Pressure induced physical properties of lead-free double perovskite Ba2GdBiO6 for optoelectronic applications

Double perovskite materials have an important role in material science, both experimentally and theoretically. This work investigates the lead-free double perovskite oxide ${Ba}_{2}GdBi{O}_6$ under varying pressure through ab initio simulations within the framework of density functional theory. The structural, optical, electrical, and mechanical characteristics of the material are determined. Key findings include the compound demonstrates thermodynamic and mechanical stability, supported by formation energy and Born stability criteria. Ductility parameters ($\nu$, B/G and $C_{12}-C_{44})$ indicate a transition from brittleness to ductility under pressure, improving machinability. Increasing pressure elevates hardness values, signifying improved elastic and plastic deformation resistance. Additionally, the material exhibits anisotropic features, which intensify with applied pressure, and its indirect band gap widens to 2.902 eV at 20 GPa. This expanded band gap suggests potential for UV and IR frequency absorption, rendering the material promising for optoelectronic devices. Furthermore, pressure enhances material strength by improving sound velocities, Debye temperature, and melting temperature, while also reducing the thermal expansion coefficient, thus enhancing material stability. These perovskites are utilized in optoelectronic applications, with high machinability and strength, particularly in UV and IR absorption.