Charge Disproportionation in Tetragonal La2MoO5 , a Small Band Gap Semiconductor Influenced by Direct Mo–Mo Bonding
Abstract
The structure of the novel compound La2MoO5 has been solved from powder X-ray and neutron diffraction data and belongs to the tetragonal space group P4/m (no. 83) with a = 12.6847(3) Å and c = 6.0568(2) Å and with Z = 8. It consists of equal proportions of bioctahedral (Mo2O10) and square prismatic (Mo2O8) dimers, both of which contain direct Mo-Mo bonds and are arranged in 1D chains. The Mo-Mo bond length in the Mo2O10dimers is 2.684(8) Å, while there are two types of Mo2O8 dimers with Mo-Mo bonds lengths of 2.22(2) and 2.28(2) Å. Although the average Mo oxidation state in La2MoO5 is 4+, the very different Mo-Mo distances reflect the fact that the Mo2O10 dimers contain only Mo5+ (d(1)), while the prismatic Mo2O8 dimers only contain Mo3+ (d3), a result directly confirmed by density function theory calculations. This is due to the complete disproportionation of Mo4+, a phenomenon which has not previously been observed in solid-state compounds. La2MoO5 is diamagnetic, behavior which is not expected for a nonmetallic transition-metal oxide whose cation sites have an odd number of d-electrons. The resistivity displays the Arrhenius-type activated behavior expected for a semiconductor with a band gap of 0.5 eV, exhibitingmore »
- Authors:
-
- Stony Brook Univ., NY (United States). Dept. of Chemistry
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
- Stony Brook Univ., NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Chemistry
- Publication Date:
- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- OSTI Identifier:
- 1261409
- Grant/Contract Number:
- AC05-00OR22725; DMR-095564; AC02-06CH11357; AC02-98CH10886.
- Resource Type:
- Journal Article: Accepted Manuscript
- Journal Name:
- Journal of the American Chemical Society
- Additional Journal Information:
- Journal Volume: 137; Journal Issue: 3; Journal ID: ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Metal-metal bonding; small band gap oxide semiconductor; charge disproportionation; infrared absorption; structure solution from powder diffraction data; 1D chains; edge-sharing bioctahedra; square prisms
Citation Formats
Colabello, Diane M., Camino, Fernando E., Huq, Ashfia, Hybertsen, Mark, and Khalifah, Peter G. Charge Disproportionation in Tetragonal La2MoO5 , a Small Band Gap Semiconductor Influenced by Direct Mo–Mo Bonding. United States: N. p., 2014.
Web. doi:10.1021/ja511218g.
Colabello, Diane M., Camino, Fernando E., Huq, Ashfia, Hybertsen, Mark, & Khalifah, Peter G. Charge Disproportionation in Tetragonal La2MoO5 , a Small Band Gap Semiconductor Influenced by Direct Mo–Mo Bonding. United States. https://doi.org/10.1021/ja511218g
Colabello, Diane M., Camino, Fernando E., Huq, Ashfia, Hybertsen, Mark, and Khalifah, Peter G. 2014.
"Charge Disproportionation in Tetragonal La2MoO5 , a Small Band Gap Semiconductor Influenced by Direct Mo–Mo Bonding". United States. https://doi.org/10.1021/ja511218g. https://www.osti.gov/servlets/purl/1261409.
@article{osti_1261409,
title = {Charge Disproportionation in Tetragonal La2MoO5 , a Small Band Gap Semiconductor Influenced by Direct Mo–Mo Bonding},
author = {Colabello, Diane M. and Camino, Fernando E. and Huq, Ashfia and Hybertsen, Mark and Khalifah, Peter G.},
abstractNote = {The structure of the novel compound La2MoO5 has been solved from powder X-ray and neutron diffraction data and belongs to the tetragonal space group P4/m (no. 83) with a = 12.6847(3) Å and c = 6.0568(2) Å and with Z = 8. It consists of equal proportions of bioctahedral (Mo2O10) and square prismatic (Mo2O8) dimers, both of which contain direct Mo-Mo bonds and are arranged in 1D chains. The Mo-Mo bond length in the Mo2O10dimers is 2.684(8) Å, while there are two types of Mo2O8 dimers with Mo-Mo bonds lengths of 2.22(2) and 2.28(2) Å. Although the average Mo oxidation state in La2MoO5 is 4+, the very different Mo-Mo distances reflect the fact that the Mo2O10 dimers contain only Mo5+ (d(1)), while the prismatic Mo2O8 dimers only contain Mo3+ (d3), a result directly confirmed by density function theory calculations. This is due to the complete disproportionation of Mo4+, a phenomenon which has not previously been observed in solid-state compounds. La2MoO5 is diamagnetic, behavior which is not expected for a nonmetallic transition-metal oxide whose cation sites have an odd number of d-electrons. The resistivity displays the Arrhenius-type activated behavior expected for a semiconductor with a band gap of 0.5 eV, exhibiting an unusually small transport gap relative to other diamagnetic oxides. Diffuse reflectance studies indicate that La2MoO5 is a rare example of a stable oxide semiconductor with strong infrared absorbance. Lastly, we show that the d-orbital splitting associated with the Mo2O8 and Mo2O10 dimeric units can be rationalized using simple molecular orbital bonding concepts.},
doi = {10.1021/ja511218g},
url = {https://www.osti.gov/biblio/1261409},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 3,
volume = 137,
place = {United States},
year = {Wed Dec 31 00:00:00 EST 2014},
month = {Wed Dec 31 00:00:00 EST 2014}
}
Web of Science