First-principle calculations of structural, electronic and optical properties of BaHfxTi1−xO3

The structural, electronic and optical properties of cubic BaHfxTi1−xO3 (x = 0, 0.25, 0.5, 0.75) (BHT) are investigated using pseudo-potential plane-wave (PP-PW) density functional theory (DFT) taking the generalized gradient approximation (GGA) as the exchange–correlation energy functional. The calculated structural parameters are consistent with the experimental results. The energy band structures, density of states (DOS), Mulliken charges and bond populations are obtained. The fundamental band gaps of BHT are all indirect and the Hf substitute can induce the band gap of BaTiO3 widening. The analysis of the structural properties, the Mulliken charges and bond populations shows that the space group of BHT becomes from Pm3m to P4mm and spontaneous polarization is caused by the substitution of Ti by Hf. The dielectric function, reflectivity spectrum, absorption coefficient, refractive index, and electron energy-loss spectrum are also calculated and analyzed in details. It is found that dielectric imaginary part of BHT decreases as Hf concentration increases.