Exploring the Structural, Elastic and Optoelectronic Properties of Stable Sr2XSbO6 (X = Dy, La) Double Perovskites: Ab Initio Calculations

This paper presents a theoretical investigation utilizing the full-potential linearized augmented planewave method (FP-LAPW) within density functional theory (DFT) framework, implemented in the Wien2k program. Analysis reveals that Sr2DySbO6 (t = 0.991) and Sr2LaSbO6 (t = 1.01) exhibit theoretical tolerance factors suggesting their crystallization in a face-centered cubic form (FCC) with space group (Fm3m; No. 225). Notably, Sr2DySbO6 demonstrates a slightly higher stability (chi_ value of 2.1207) compared to Sr2LaSbO6 (chi_ value of 1.9902). Both compounds also show negative formation energies, suggesting that they are feasible for experimental synthesis and structurally stable. Stability is further confirmed by structural optimization by atomic relaxation and total energy reduction against unit cell volume. Both compounds exhibit ductility, anisotropy, ionic bonding nature, elastic stability, resistance to plastic deformation, and central force crystal properties. Sr2DySbO6 electronic characteristics reveals that it is metallic, whereas Sr2LaSbO6 is insulating. Energy-wise, optical properties are assessed between 0 and 15 eV. Both the compounds have demonstrated noteworthy UV responses are making use of the unique characteristics and high energy of UV light for a range of creative uses. Overall, these findings advocate for experimental exploration of these compounds, hinting at potential applications.