First-principles study of structural, elastic, electronic and optical properties of cubic perovskite AgXF3 (X = Be, Mg, Ca and Sr) compounds

The structural, elastic, electronic and optical properties of cubic fluoroperovskite crystal AgXF3 (X = Be, Mg, Ca and Sr) were studied using the first-principles method. The optimized lattice constant a0 increases by varying the cation from Be to Sr, which is consistent with previous reports. The calculations of electronic band structure show that AgBeF3, AgMgF3 and AgCaF3 have indirect band gaps, while AgSrF3 has direct band gaps. The band gaps of AgBeF3, AgMgF3, AgCaF3 and AgSrF3 are 1.820, 1.901, 2.074 and 1.795 eV, respectively, which all exhibit semiconducting properties. It is further found that as the cation changes from Be to Sr, the top of the valence band approaches the Fermi level. The nature of chemical bonds in these compounds is discussed by the electron localization function. The optical properties of AgXF3 (X = Be, Mg, Ca and Sr), including the reflectance, absorption, refractive index, dielectric function, conductivity and loss function have been studied, and the wide range of absorption energies makes these materials promising for significant applications in semiconductor fields. [Display omitted]