Theoretical Study of (La, Mn) Codoping on the Modification of Photonic Performance in BaTiO₃ Materials

This study aimed to investigate the structure, electronic, ferroelectric, and optical properties of primitive BaTiO₃ (BTO) and (Ba_0.875La_0.125)(Ti_0.875Mn_0.125)O₃ (BLTM) using density functional theory and the generalized gradient approximation plane wave pseudopotential technique. Co-doping with (La, Mn) reduces the tetragonality of BTO, resulting in a pseudocubic configuration of its unit cell. The incorporation of dopant elements introduces impurity levels within the material's band structure, thereby reducing the bandgap and enhancing its light absorption capability. Simultaneously, BLTM exhibits low effective carrier mass and high electrical conductivity. Analysis of its optical properties reveals a high absorption coefficient and pronounced photorefractivity, with a red shift in the absorption peak, demonstrating high absorption rates in both the infrared and visible light regions. The results show that the differences in the ionic radius and electronegativity of the dopant elements lead to changes in the crystal structure and chemical bonding properties of the materials, which in turn affect the electron cloud density of the materials and ultimately effectively improve the material properties.