Band-gap narrowing in α-(CrxFe1-x)2O3 solid-solution films

Abstract

We report on structural and optical properties for the (0001)-oriented α-(CrxFe1-x)2O3 (0 ≤ x ≤ 1) epitaxial films prepared on c-sapphire substrates by using pulsed-laser deposition. Pure corundum phase with atomically flat surface was obtained in the entire composition range. Optical absorption spectra for the films with 0.2 < x < 0.9 showed a nearly constant band-gap (1.7 eV), which is narrower than those of α-Fe2O3 (2.1 eV) and α-Cr2O3 (3.0 eV). The result suggests that the band-gap narrowing arises from a type-II band alignment of these oxides and the fundamental band-gap lies between the Cr t2g and O 2p occupied states and the Fe t2g* empty state.

Zn Doped α-Fe2O3: An Efficient Material for UV Driven Photocatalysis and Electrical Conductivity

“…In addition, this decrease in band gap may also be due to partial hybridization between Zn t 2g and O 2p states to empty Fe t* 2g 3d orbitals. A report by Mashiko et al explained the decrease in band gap on the basis of decrease in residual in-plane strain [33]. Based on the above considerations, the sequence of band gap for synthesized samples is Zn 6% > Pure Fe 2 O 3 > Zn 2% > Zn 4% which agrees well with experimental data and measured band gap values are given in Table 2.…”

“…These hydroxyl radicals are, thus, more efficient for degradation of RB dye into some non-toxic organic compounds, such as CO 2 and H 2 O, as shown in Figure 7. The oxidative (using holes) and reductive (using electrons) pathway, followed by the degradation process, are summarized as follows [33,37]:…”

Intrinsic Properties of Pure and Mixed Monolayer Oxides in the Honeycomb Structure: M2O3 and MM′O3 (M, M′ = Ti, V, Cr, Fe)

“…[32][33][34][35][36][37] we have predicted the existence of mixing-induced redox reactions in bulk TiVO 3 and TiFeO 3 compounds, resulting in a stabilization of Ti 4+ , V 2+ , and Fe 2+ oxidation states, different from those found in the pure bulk M 2 O 3 oxides. The present results show that, despite the same stoichiometry, the changes of cation oxidation states do not concern the same mixed compounds in 2D and 3D.…”

Band-Gap Reduction in (BiCrO3)m/(BiFeZhang1, Xiao2, Peng3 et al. 2018Phys. Rev. Applied392150View full textAdd to dashboardCite

“…GaN) n /(AlN) n (n = 10, 12, 14)[66] as well as nanocomposites of Carbon-ZrO 2[67] , NiO:TiO 2[68] and Fe 2 O 3 -Cr 2 O 3 systems[69][70][71].For the band gap reduction with the increasing layer number of BFO or BCO, the lattice strain induced by the lattice mismatch between BFO and BCO may be one of the reasons responsible for that. In order to explore how the lattice strain influences the band gap, we investigate the band gap of BFO and BCO within 2 % tensile and compressive strain, respectively.…”