Coulomb‐correlation effects on the optical properties of β‐Mn₂V₂O₇

Abstract

Electronic structure and optical properties of b-Mn 2 V 2 O 7 were studied using the density-functional theory with the generalized gradient approximation (GGA) and including the on-site electron correlations (GGA þ U). The GGA functional alone gives the insulating antiferromagnetic state, but cannot explain the observed color of b-Mn 2 V 2 O 7 . We discussed the sensitivity of optical properties toward U and concluded that the U-Hubbard term to the Mn 3d states $4 eV is able to reproduce the experimental optical band gap. The low absorption coefficient, reflectivity, and refractive index obtained up to 3 eV predict the good reflection properties of this complex oxide. 1 Introduction The manganese divanadate Mn 2 V 2 O 7 exhibits the optical, thermoelectric, and magnetic properties that are of interest for technological applications as well as for fundamental studies [1][2][3][4][5][6][7]. Mn 2 V 2 O 7 is a unique dark pigment with a high reflectance in the infrared spectral range and can reduce the IR-induced heat accumulation that may be applicable in developing paints and coatings for automotive, aerospace, and construction industries [5]. This compound belongs to the family of ternary oxides M 2 X 2 O 7 which may exist in two modifications and have the reversible phase transition [1,6,7]. The low-temperature phase a-Mn 2 V 2 O 7 crystallizes in a triclinic structure (space group P 1, Z ¼ 4) with a ¼ 6. It is clear that the optical properties of b-Mn 2 V 2 O 7 are related to its electronic structure; however, no theoretical

Ambient Light-Activated Antibacterial Material: Manganese Vanadium Oxide (Mn2V2O7)

“…The β-phase has a band gap of 1.7 eV, so MVO absorbs visible light up to ∼700 nm. 19 CBM and VBM of β-Mn 2 V 2 O 7 are at 4.33 and 6.06 eV below vacuum level, respectively, 20 which matches the redox potential of water (Figure 1b). 21 Under visible light, MVO reduces bacterial load by 4 orders of magnitude.…”

“…This work reports a new antibacterial photocatalyst, Mn 2 V 2 O 7 (MVO), that works in ambient light or low-intensity solar radiation. The β-phase has a band gap of 1.7 eV, so MVO absorbs visible light up to ∼700 nm . CBM and VBM of β-Mn 2 V 2 O 7 are at 4.33 and 6.06 eV below vacuum level, respectively, which matches the redox potential of water (Figure b) .…”

Suitability of Cu-substituted β-Mn2V2O7 and Mn-substituted β-Cu2V2O7 for photocatalytic water-splitting

“…We used the linear-response scheme proposed by Cococcioni 27 to determine the U values of 4.1 eV for Mn and 3.9 eV for V, which agree well with other theoretical studies of MVO. 1,28 The same approach resulted in U = 9.8 eV for copper, which was combined with J = 1.2 eV, motivated by the fact that J improves the description of the magnetic state of CuO, which is also a Cu(II) compound. 29 This setup differs from other CVO calculations that used either an effective U eff = U − J = 6.52 eV 4,30 or U Cu = 7 eV and J Cu = 1 eV.…”

Suitability of $β$-Mn$_2$V$_2$O$_7$/$β$-Cu$_2$V$_2$O$_7$ solid solutions for photocatalytic water-splitting

“…We used the linear-response scheme proposed by Cococcioni [26] to determine U values of 4.1 eV for Mn and 3.9 eV for V, which agree well with other theoretical studies of MVO. [1,27] The same approach resulted in U=9.8 eV for copper, which was combined with J=1.2 eV, motivated by the fact that J improves the description of the magnetic state of CuO, which is also a Cu(II) compound. [28] This setup differs from other CVO calculations that used either an effective U eff = U − J = 6.52 eV [4,29] or U Cu =7 eV and J Cu =1 eV.…”