Effect of Hydrostatic Pressure on Structural, X-Ray Diffraction, Electronic, Optical and Thermoelectric Features of XNbO3 (X = Na, K) Perovskites for Renewable Energy Application: A First Principles Study

초록

This article explores the physical properties of XNbO3 (X = Na, K) perovskites under pressure via the density functional theory to use as potential renewable energy applications. Specifically, the structural, Powder X-ray diffraction, electronic, optical, and thermoelectric characteristics of XNbO3 (X = Na, K) under hydrostatic pressures ranging from 0 to 50 GPa are examined to vindicate the compounds superiority for valuable applications. The analysis shows significant structural compression with pressure, reducing lattice parameters and cell volume while keeping the cubic phase. X-ray diffraction indicates peaks shift towards high angles, with NaNbO3 and KNbO3 exhibiting well-defined peaks, validating phase stability under pressure. Dynamical stability has been evaluated using molecular dynamics simulations. Pressure causes an increase in the bandgap, shifting from 1.284 to 1.830 eV for NaNbO3 and from 1.489 to 1.814 eV for KNbO3 while keeping an indirect band gap. Optical properties, also enhanced when pressure is devoted, show a prominent increase in absorption in the visible region. The analysis utilizing the BoltzTrap code delved deeper into the temperature-dependent characteristics of these materials. The study concentrated on the thermal and electrical conductivities of the materials, the Seebeck coefficient, and various other relevant metrics.

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