Tailoring morphological, elastic, and thermodynamic properties of Ag2BeSnX4 (X = S, Se, Te) kesterites: a computational approach

In this study, a computational analysis based on density functional theory is conducted to study the elastic, mechanical, vibrational, and thermodynamic properties of novel chalcogens, Ag₂BeSnX₄ (X = S, Se, and Te). We used the generalized gradient approximation (GGA) within the framework of density functional theory (DFT). The mesh parameter values (a and c) were calculated using the X-ray diffraction method. The calculated elastic constants indicate that the bond strength along the [1 0 0] directions is stronger than that along the direction [0 0 1]; according to the Born-Huang stability criterion, we can see that they are mechanically stable. A high value of the ratio (B/G) is associated with ductility for Ag₂BeSnX₄ (X = S, Se, and Te) materials. Additionally, the Raman shifts of all samples are calculated. Between 10 and 1000 K in temperature, the vibrational mode shifts were calculated for three chalcoginides. The thermal behavior of these movements shows that these structures can undergo deformation with increasing temperature. These results suggest a first contribution to the understanding of the effect of temperature on the vibrational modes of three kesterite structures Ag₂BeSnX₄ (X = S, Se, and Te) and consequently on their structures. The heat capacity \(({C}_{V})\), free energy \((F)\), entropy \((S)\), and enthalpy \((H)\) are also computed. The kesterite phase of the Ag₂BeSnX₄ (X = S, Se, and Te) structures aligns with theoretical findings in elastic properties, exhibiting superior elastic properties. These attributes are valuable for the design of optoelectronic devices.