Analysis of cubic perovskite oxide AgNbO3 under stress conditions: Potential for photovoltaic and high-temperature applications - A DFT study

In the family of perovskite materials, perovskite oxide gained considerable attention from researchers in diverse fields, due to their flexible chemistry. Here, cubic perovskite oxide AgNbO3 was studied using DFT via CASTEP code, to explore the key properties under varying stress conditions ranging from 0 to 100 GPa. Phase stability was confirmed by XRD analysis. Electronic properties confirmed the increasing trend in the band gap from 1.422 eV to 1.722 eV, with increasing stress. Optical characteristics reveal high absorption, conductivity, and lower loss function. Significantly, the elastic constants (C11, C12, and C44) satisfy the Born-stability criteria, ensuring the mechanical stability of the considered compound. Moreover, the Poisson ratio, Pugh's ratio (B/G), Frantsevich ratio, Cauchy pressure (PC), and anisotropic factor ensure the ductile nature as well as an anisotropic character over the entire stress range. The positive trajectory in phonon density confirms the thermal stability. Thermodynamically, the studied material shows high-temperature stability with a higher value of applied stress as confirmed by Debye temperature (θD). Furthermore, an inverse association of enthalpy and total entropy with free energy was observed. Based on these findings, confidently suggested that the considered cubic perovskite oxide, AgNbO3, can be efficiently used for photovoltaic and high-temperature applications.