The effects of Sc doping and O vacancy on the electronic states and optical properties of m-BiVO<sub>4</sub>
Bibliographic record
Abstract
Based on density functional theory (DFT), the effects of scandium (Sc) doping and oxygen vacancy (VO) on the electronic states and optical properties of monoclinic BiVO4 (m-BiVO4) are investigated. The generalized gradient approximation plus U (GGA+U) method is adopted during the calculation of the electronic properties to compensate for the limitations of the DFT method. The ideal m-BiVO4 has a direct band gap of 2.400 eV, and if Bi in m-BiVO4 is substituted by Sc (subSc-Bi), the direct band gap will be reduced to 2.393 eV. However, if V is replaced by Sc (subSc-V) as well as oxygen vacancy induced (subSc–V+VO), the band gap will become indirect with values of 1.913 and 2.198 eV, respectively. The reduction capability is in the sequence of subSc–Bi > ideal > subSc–V+VO > subSc–V, while the oxidation capability is in the order of ideal > subSc–Bi > subSc–V+VO > subSc–V. The ε1(0) of the ideal, subSc–Bi, subSc–V, and subSc–V+VO defective m-BiVO4 are 8.290, 8.293, 12.791, and 8.285, respectively. The optical absorptions of ideal and subSc–Bi m-BiVO4 show anisotropy and they are nearly independent of the defect concentration. SubSc–V m-BiVO4 exhibits stronger absorption than the other three semiconductors. The absorptions of subSc–V+VO m-BiVO4 vary widely with the defect concentrations, where 3.906% defect concentration of m-BiVO4 has the strongest absorption. The estimated optical band gaps [Formula: see text] are smaller than Eg for ideal and defective m-BiVO4.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".