First principle investigation of the structural, electronic, optical, and elastic properties of Ba-based fluoroperovskite (BaYF3; Y = Li, Na, K, and Rb) compounds

The BaYF3 (Y = Li, Na, K, and Rb) materials as cubic fluoro-perovskite compounds were examined by exploiting the full electron potential technique (FP-LAPW) and DFT through space of the Wien2k package to analyze their electronic and optical characteristics. The structural characteristics were determined through the generalized gradient approximation PBE-GGA functional, while the TB-mBJ functional was applied to enhance the calculation of electronic and optical characteristics. By substituting the cation Y from Li to Na, K, and Rb elements, the lattice constant experiences an increase, but the bulk modulus undergoes a drop. By studying the density of states and energy band structure, it is evident that BaYF3 (Y = Li, Na, K, or Rb) exhibits a direct (Γ−Γ) energy band gap as insulator compounds. The obtained band gaps are 8.33 eV for BaLiF3, 7.75 eV for BaNaF3, 6.27 eV for BaKF3, and 5.35 eV for BaRbF3. The dielectric function and some connected optical characteristics, including refractive index, absorption coefficient, extinction coefficient, and reflectivity, have been evaluated in the 0−30 eV energy range. Due to their excellent absorption and reflection capabilities in the UV spectrum, we prefer exploiting these compounds for optoelectronic applications, specifically in the UV region. Also, we have characterized the elastic constants (C11, C12, and C44) of the perovskite BaYF3 compounds and their corresponding mechanical parameters by using WC-GGA approximation.