Calcium effects on phase stability, elastic, electronic, optical and thermal properties of Ba1-xCaxPo ternary alloys

In this study, the elastic, optoelectronic, and thermal properties of the stable phase of BaPo and CaPo chalcogenide compounds, along with their ternary alloys, formulated as Ba1-xCaxPo, over a concentration range of 0 ≤ x ≤ 1, are investigated. The analysis is performed using the full-potential (FP) linearized augmented plane wave plus local orbital (APW+lo) method within the framework of density functional theory (DFT) and realized within the WIEN2k computational package for crystalline solids. Based on the computed elastic constants, the mechanical stability of these materials is confirmed through the application of Born’s stability criteria. From the band structure calculations, it is found that the Ba1-xCaxPo exhibit a direct band gap at the Γ point, whereas the binary compounds possess an indirect band gap (Γ–X). Furthermore, the band gap energy of Ba1-xCaxPo alloys shows a nonlinear dependence on Ca concentration. The calculated optical band gap values and absorption coefficients are found to be promising, suggesting that the Ba1-xCaxPo alloys are strong candidates for optoelectronic devices applications. To evaluate the thermal behavior of the alloy system, the quasi-harmonic Debye model is employed. Our computational results are compared with available literature data, and a detailed discussion is provided. This study also offers qualitative insights into the behavior of group 2 polonides. The findings may serve as a foundation for future research on the potential applications of these materials.