The role of an unintentional carbon dopant in resolving the controversial conductivity aspects in BiFeO₃

Abstract

The electronic structure and properties of carbon incorporated BiFeO3, and resolution to the conductivity aspects of BiFeO3.

Theoretical insight of origin of Rashba–Dresselhaus effect in tetragonal and rhombohedral phases of BiFeO3

“…The bandgap obtained using the GGA+ U formalism without SOC is 2.48 eV, which is quite close to the experimental value (2.6–2.7 eV). 57,58 The inclusion of SOC leads to the splitting of the band at M , and thus, the CBm is shifted to a point 0.049 Å −1 away from M towards K along with a decrease in the bandgap, indicating the importance of heavy-atom-induced SOC in the calculations. An anisotropic splitting of the band is observed around point M (as shown in the inset of Fig.…”

Role of H impurity as compensating center in BiFeO3 by first-principle calculations

“…The nature of conductivity in BiFeO 3 (BFO), whether p-type or n-type, is quite controversial and may be altered by introducing various defects and dopants. In our recent work, carbon is found to be a possible extraneous factor for causing p-type conductivity in BiFeO 3 [2]. Because of the small ionic radius (∼ 0.2-0.4 Å) [6], an H atom is more likely to occupy interstitial sites in BFO.…”

“…Incorporation of elements like Hydrogen (H), Lithium (Li), Carbon (C) during material fabrication is quite evident owing to small radii (H and Li) and ubiquitous nature (C) [1][2][3]. The most abundant source of H is the presence of H 2 gas and humidity (H 2 O) in the stratosphere.…”

Photocatalytic mechanism and performance of a novel wool flake–BiFeO3 nanosheet–TiO2 core–shell-structured composite photocatalyst

“…This suggests that the two elements Fe and Bi in the surface of the wool-BFO composites are covered by a thick layer of TiO 2 , which is in conwith the EDX mapping and TEM observation. When wool flakes are ground with BFO nanosheets under vacuum freeze-drying conditions, besides the sub-peaks of C-H/ C-C, C-N, C-O, C=O and N-C=O in the C1s core-level XPS spectra of wool flakes (figure S4(a)), a new sub-peak at 283.27 eV in the wool-BFO composites is probably attributed to the binding energy of C-Fe/C-Bi (figure S4(e)), which results in p-type conductivity in BFO [66]. It was demonstrated that the Bi and Fe cation vacancies could lead to the introduction of acceptor-type defect levels in the band gap of BFO [66].…”

“…When wool flakes are ground with BFO nanosheets under vacuum freeze-drying conditions, besides the sub-peaks of C-H/ C-C, C-N, C-O, C=O and N-C=O in the C1s core-level XPS spectra of wool flakes (figure S4(a)), a new sub-peak at 283.27 eV in the wool-BFO composites is probably attributed to the binding energy of C-Fe/C-Bi (figure S4(e)), which results in p-type conductivity in BFO [66]. It was demonstrated that the Bi and Fe cation vacancies could lead to the introduction of acceptor-type defect levels in the band gap of BFO [66]. For the N1s core-level XPS spectra, the N-H sub-peak of wool flakes (figure S4(b)) disappears and two new sub-peaks at the binding energies of 397.42 eV (N−Fe) and 398.57 eV (N−Bi) (figure S4(f)) [67] are fitted.…”