First-principles study of structural, vibrational and dielectric properties of double perovskites Ba2LnSbO6 (Ln = Sm, Gd, Dy and Y)

► Ab initio study of Ba2LnSbO6 (Ln = Sm, Gd, Dy and Y) have been done for the first time. ► Lattice constants and oxygen internal parameters calculated. ► Bulk modulus and pressure derivative are calculated for the first time. ► Raman and infrared modes are calculated and compared with the experimental values. ► Born effective charges and dielectric constants have been calculated.