The electronic structures of vanadate salts: Cation substitution as a tool for band gap manipulation

Journal Article · Wed Jul 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.04.032· OSTI ID:21370508

Dolgos, Michelle R; Paraskos, Alexandra M; Stoltzfus, Matthew W; Yarnell, Samantha C ^[1]

---

1. Ohio State University, Department of Chemistry, 100 West 18th Avenue, Columbus, OH 43210 (United States)

The electronic structures of six ternary metal oxides containing isolated vanadate ions, Ba{sub 3}(VO{sub 4}){sub 2}, Pb{sub 3}(VO{sub 4}){sub 2}, YVO{sub 4}, BiVO{sub 4}, CeVO{sub 4} and Ag{sub 3}VO{sub 4} were studied using diffuse reflectance spectroscopy and electronic structure calculations. While the electronic structure near the Fermi level originates largely from the molecular orbitals of the vanadate ion, both experiment and theory show that the cation can strongly influence these electronic states. The observation that Ba{sub 3}(VO{sub 4}){sub 2} and YVO{sub 4} have similar band gaps, both 3.8 eV, shows that cations with a noble gas configuration have little impact on the electronic structure. Band structure calculations support this hypothesis. In Pb{sub 3}(VO{sub 4}){sub 2} and BiVO{sub 4} the band gap is reduced by 0.9-1.0 eV through interactions of (a) the filled cation 6s orbitals with nonbonding O 2p states at the top of the valence band, and (b) overlap of empty 6p orbitals with antibonding V 3d-O 2p states at the bottom of the conduction band. In Ag{sub 3}VO{sub 4} mixing between filled Ag 4d and O 2p states destabilizes states at the top of the valence band leading to a large decrease in the band gap (E{sub g}=2.2 eV). In CeVO{sub 4} excitations from partially filled 4f orbitals into the conduction band lower the effective band gap to 1.8 eV. In the Ce{sub 1-x}Bi{sub x}VO{sub 4} (0<=x<=0.5) and Ce{sub 1-x}Y{sub x}VO{sub 4} (x=0.1, 0.2) solid solutions the band gap narrows slightly when Bi{sup 3+} or Y{sup 3+} are introduced. The nonlinear response of the band gap to changes in composition is a result of the localized nature of the Ce 4f orbitals. - Graphical abstract: The electronic structures of six vanadate salts, Ba{sub 3}(VO{sub 4}){sub 2}, Pb{sub 3}(VO{sub 4}){sub 2}, YVO{sub 4}, BiVO{sub 4}, Ag{sub 3}VO{sub 4} and CeVO{sub 4}, are studied. The results show that the oxygen to vanadium charge transfer, which is largely responsible for the electronic structure near the Fermi level, can be altered significantly through interactions with the surrounding cations.

• OSTI ID: 21370508
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 7; Other Information: DOI: 10.1016/j.jssc.2009.04.032; PII: S0022-4596(09)00166-2; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
BISMUTH IONS
CATIONS
CERIUM COMPOUNDS
ELECTRONIC STRUCTURE
EV RANGE 01-10
FERMI LEVEL
LEAD COMPOUNDS
OXIDES
PHOTOCATALYSIS
SILVER COMPOUNDS
SOLID SOLUTIONS
VANADATES
YTTRIUM COMPOUNDS
YTTRIUM IONS
ALKALINE EARTH METAL COMPOUNDS
CATALYSIS
CHALCOGENIDES
CHARGED PARTICLES
DISPERSIONS
ENERGY LEVELS
ENERGY RANGE
EV RANGE
HOMOGENEOUS MIXTURES
IONS
MIXTURES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS