Impact of Pressure on the Physical, Mechanical, and Thermal Properties of the Ternary Halide Perovskite AgCaCl₃: A First-Principles Investigation

AgCaCl₃, an inorganic halide perovskite material, is recognized for its high stability and environmental compatibility, making it a promising candidate for significant applications in optoelectronics and lens manufacturing. This study focused on investigating the electronic properties of AgCaCl₃, including its density of states and band structure. The results revealed that AgCaCl₃ consistently exhibits an indirect band gap of around 1.5 eV across the pressure range examined. Furthermore, its dielectric function, absorption coefficient, optical conductivity, reflectivity, and refractive index indicated that AgCaCl₃ maintains its optical properties under the conditions studied. The mechanical properties were also analyzed, with calculations of elastic constants (C₁₁, C₁₂, and C₁₄) providing insights into the material's dynamic stability. Parameters such as the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and anisotropy factor suggest that the material is ductile. Additionally, thermal properties, including the Debye temperature, isobaric and isochoric heat capacities, thermal expansion coefficient, Gibbs free energy, and entropy, were thoroughly examined.

Methods
This study utilized DFT calculations, implemented in the Wien2K code, to explore the mechanical and thermal properties of AgCaCl₃ under varying pressure conditions. Its electronic and optical properties were optimized using the PBE-GGA functional. Its mechanical and thermodynamic properties were calculated using the ElaStic and Gibbs2 codes.

Results and conclusions

This study investigates the physical, mechanical, and thermal properties of AgCaCl3 under different pressures. The results show a decrease in its volume and lattice constants as pressure increases, while the material maintains its semiconductor properties and stable optical behavior. These computational findings highlight AgCaCl3's potential for use in deep-sea devices and lenses. Its elastic properties were found to increase linearly with the applied pressure, and its thermal characteristics, modeled using the quasi-Debye approach, provided detailed insights into the material’s response. These outcomes form a solid foundation for future experimental work, supporting the development and application of AgCaCl3 in optoelectronic devices.