Electrical and optical properties of three BaTiO3 crystal phases by the first-principles study

The study on the properties of barium carbonate in different crystal systems is play an important role for the evolution of electronic products requiring miniaturization and high performance. Here, the electrical and optical properties of BaTiO₃ crystal structures with three space groups (Pm<SPAN STYLE="text-decoration:overline">3</SPAN>m, P4mm, and P4/mmm) were systematically studied using the first-principles method. The structural are confirmed to be stable by the Born criterion The evolution energy band structures under HSE06 functional were more consistent with other theoretical and experimental results compared to the PBE functional. The band gaps of BaTiO3 for Pm<SPAN STYLE="text-decoration:overline">3</SPAN>m, P4mm, and P4/mmm space groups up to 3.42, 3.24, and 3.26 eV and exhibit indirect semiconductor behavior. The optical parameters show that the light absorption rate and loss function of all three BaTiO₃ were almost zero in the lower energy range. However, the tetragonal phase BaTiO₃ with P4/mmm space group has a lower light reflection rate and higher light refractive index compared to the tetragonal phase BaTiO₃ with P4/mmm and the cubic phase BaTiO₃ with Pm<SPAN STYLE="text-decoration:overline">3</SPAN>m space group, indicating its potential application value in electro-optic modulation.