Search Results (2)

In this study, we review our first-principles simulations for STO/BTO, STO/PTO, and SZO/PZO (001) heterostructures. Specifically, we report ab initio B3PW calculations for STO/BTO, STO/PTO, and SZO/PZO (001) interfaces, considering non-stoichiometric heterostructures in the process. Our ab initio B3PW calculations demonstrate that charge redistribution in the (001) interface region only subtly affects electronic structures. However, changes in stoichiometry result in significant shifts in band edges. The computed band gaps for the STO/BTO, STO/PTO, and SZO/PZO (001) interfaces are primarily determined according to whether the topmost layer of the augmented (001) film has an AO or BO₂ termination. We predict an increase in the covalency of B-O bonds near the STO/BTO, STO/PTO, and SZO/PZO (001) heterostructures as compared to the BTO, PTO, and PZO bulk materials. Full article

We performed predictive hybrid-DFT computations for PbTiO₃, BaTiO₃, SrTiO₃, PbZrO₃ and SrZrO₃ (001) surfaces, as well as their BaTiO₃/SrTiO₃, PbTiO₃/SrTiO₃ and PbZrO₃/SrZrO₃ (001) heterostructures. According to our hybrid-DFT computations for BO₂ and AO-terminated ABO₃ solid (001) surfaces, in most cases, the upper layer ions relax inwards, whereas the second layer ions shift upwards. Our hybrid-DFT computed surface rumpling s for the BO₂-terminated ABO₃ perovskite (001) surfaces almost always is positive and is in a fair agreement with the available LEED and RHEED experiments. Computed B-O atom chemical bond population values in the ABO₃ perovskite bulk are enhanced on its BO₂-terminated (001) surfaces. Computed surface energies for BO₂ and AO-terminated ABO₃ perovskite (001) surfaces are comparable; thus, both (001) surface terminations may co-exist. Our computed ABO₃ perovskite bulk Γ-Γ band gaps are in fair agreement with available experimental data. BO₂ and AO-terminated (001) surface Γ-Γ band gaps are always reduced with regard to the respective bulk band gaps. For our computed BTO/STO and PTO/STO (001) interfaces, the average augmented upper-layer atom relaxation magnitudes increased by the number of augmented BTO or PTO (001) layers and always were stronger for TiO₂-terminated than for BaO or PbO-terminated upper layers. Our B3PW concluded that BTO/STO, as well as SZO/PZO (001) interface Γ-Γ band gaps, very strongly depends on the upper augmented layer BO₂ or AO-termination but considerably less so on the number of augmented (001) layers. Full article