A comparative study on the physical properties of Ba2XIO6 (X = Li, K) double perovskites alloys

This work concerns the study of the physical properties of Ba2XIO6 (X = Li, K) double perovskites alloys using first principles approach since the density functional theory implemented in Wien2k code. The exchange-correlation potential is treated by WC-GGA and mbJ-GGA. The negative formation energy of both alloys confirms the dynamic stability. Further, the elastic constants reveal that these compounds are mechanically stable and can be synthesized experimentally. The bulk, shear moduli, Young, Poisson's ratio, anisotropic factor, and Vickers hardness values for these materials are determined using the results of the elastic constants. The Young's modulus 3D representation showed that the Ba2KIO6 material displays a strong anisotropy compared to Ba2LiIO6. Furthermore, the analysis of electronic band structures and the density of states reveal a semiconducting nature with direct band gaps of 2.340 eV, 4.213 eV 2.350 eV and 4.027 eV for Ba2LiIO6 and Ba2KIO6, respectively, using WC-GGA and TB-mBj-GGA. Moreover, optical functions: absorption, refractive index, reflectivity and loss function are obtained.