DFT Investigation of the Influence of Be Substitution on the Physical Properties of CsCdCl ₃ Perovskite

ABSTRACT

The effects of beryllium (Be) doping in the cubic structure of CsCdCl ₃ perovskite were explored using density functional theory (DFT) under the generalized gradient approximation (GGA) with ultrasoft pseudopotentials (USPs). Three different Be incorporation concentrations (6%, 11%, and 14%) were investigated to study the doping‐induced modifications. The structural stability of the doped systems was confirmed by observing small changes in the lattice constant and lattice volume owing to Be substitution, as revealed by the optimized structural parameters. Optical studies revealed good absorption in the UV region, and the optical conductivity, dielectric response, refractive index, and reflectivity also increased with increasing Be incorporation. Thermodynamic analysis revealed that Be ion doping significantly affected the entropy, heat capacity, free energy, enthalpy, and Debye temperature, indicating enhanced thermal responsiveness and modified lattice dynamics. The soft vibrations and lattice distortions due to doping were confirmed by calculations of the phonon density of states and phonon dispersions, which further supported the changes in the lattice dynamical stabilities. The results indicate that Be‐doped CsCdCl ₃ has tunable electronic and optical properties, which is a significant benefit for applications in energy conversion, UV radiation devices, and photovoltaic devices.