研究目的
Investigating the electronic, band structural, and optical properties of BixSr1-xTiO3 perovskite using first-principles density functional theory.
研究成果
The DFT calculation results reveal that the binding energy decline in BixSr1-xTiO3 (x>0) structures. The substitution of Bi ions in A site can influence the band gaps of ABO3 perovskite complex oxide. The absorption spectra indicate that the ultraviolet absorption performance can be improved in BiTiO3 system, which may effectively improve the photo-catalytic activity. Bi-based perovskite BiTiO3 would be a potential photocatalytic material.
研究不足
The band gap calculated by GGA is lower than the experimental value due to the function itself, which cannot be used to make accurate calculation of the absolute energy. However, the relative value is still very accurate for analyzing the band structure and electronic properties.
1：Experimental Design and Method Selection:
The study employs the first-principles plane-wave ultrasoft pseudopotential method within the framework of density functional theory (DFT) with generalized gradient approximation (GGA) by Perdew-Burke-Ernzerhof (PBE) for geometry optimization, electronic and band structure calculations. The band gap values were further calculated by norm-conserving pseudopotential method using HSE06 for accuracy.
2：Sample Selection and Data Sources:
Models of perovskite-type oxides BixSr1-xTiO3 (x=0, 0.25, 0.5, 0.625, 1) were set up. The crystal structures were energy-optimized and then calculated for X-ray diffraction (XRD) structures using powder diffraction in Reflex module.
3：25, 5, 625, 1) were set up. The crystal structures were energy-optimized and then calculated for X-ray diffraction (XRD) structures using powder diffraction in Reflex module.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: The study utilized the CASTEP code for calculations. The basis set of the valence electronic states are taken as: 6s26p3, 4s24p65s2, 3s23p63d24s2, and 2s22p4 for Bi, Sr, Ti, and O, respectively.
4：Experimental Procedures and Operational Workflow:
The cutoff kinetic energy of the electron wave function was set to 340 eV, and the k-point sampling set 3×3×3 division of the reciprocal unit cell based on the Monkhorst-Pack scheme was used. Geometrical optimization was conducted using the convergence of thresholds of 5×10-6 eV/atom for the total energy, all forces on atoms were converged to less than 0.01 eV/?, the maximum ionic displacement was within 0.0001 ? and the total stress tensor was reduced to the order of 0.02 GPa.
5：01 eV/?, the maximum ionic displacement was within 0001 ? and the total stress tensor was reduced to the order of 02 GPa.
Data Analysis Methods:
5. Data Analysis Methods: The electronic total charge density, band structures, density of states, and optical properties were analyzed to understand the bonding character, band gap, and photocatalytic activity of BixSr1-xTiO3.
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