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Niobium triselenide
Names
	IUPAC name Niobium triselenide
Identifiers
CAS Number	12034-78-5;
3D model (JSmol)	Interactive image;
ChemSpider	65793970;
PubChem CID	9797567 has charge error;
	InChI InChI=1S/Nb.3Se Key: SURUPJMVQWNAQN-UHFFFAOYSA-N;
	SMILES [Se]=[Nb]1[Se][Se]1;
Properties
Chemical formula	NbSe3
Molar mass	1292.425 g/mol
Appearance	black powder, silvery crystals
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Niobium triselenide is an inorganic compound belonging to the class of transition metal trichalcogenides. It has the formula NbSe₃. It was the first reported example of one-dimensional compound to exhibit the phenomenon of sliding charge density waves.^[1] Due to its many studies and exhibited phenomena in quantum mechanics, niobium triselenide has become the model system for quasi-1-D charge density waves.

Structure

Niobium triselenide has a highly anisotropic structure. The Nb⁴⁺ centers are bound within trigonal prisms defined by six Se ligands. Two pairs of these six Se atoms are bonded to each other to make the polyselenide Se2−2; the other two exist as the monatomic Se²⁻.^[2] The NbSe₆ prisms form infinite co-parallel chains. Although the prisms share the same coordination, the cell consists of three chain types repeated twice, where each chain is defined by its Se–Se bond length. The Se–Se bond lengths are 2.37, 2.48, and 2.91 angstroms.^[3]^[4]

Synthesis

The compound is prepared by the solid state reaction by heating niobium and selenium at 600 to 700 °C:

Nb + 3 Se → NbSe₃

The resulting black crystals can contain NbSe₂ impurities. Samples can be purified by chemical vapor transport (CVT) between 650 and 700 °C. The lower limit of CVT was determined by the temperature at which NbSe₂ is no longer stable.^[5]

Properties

Measurements on NbSe₃ provided significant evidence for charge density wave (CDW) transport, CDW pinning, magnetism, Shubnikov-de Hass oscillations, and the Aharonov–Bohm effect.

The electrical resistivity of most metallic compounds decrease as temperature decreases. For the most part NbSe₃ follows this trend except two anomalies exist where electrical resistivity reaches two local maxima at 145 K (−128 °C) and 59 K (−214 °C). The maxima result in a sharp decrease in electrical conductivity. This observation is explained by the charge density wave formations that open the gaps in the Fermi surface. The opening causes the 1-D linear system to behave more like a semiconductor and less like a metal, a transition commonly known as Peierls transition. NbSe₃ continues to be metallic despite the Peierls transition because the charge density wave formation does not completely remove the Fermi surface, a phenomenon known as imperfect Fermi surface nesting.^[6]

In the form of nanofibers, NbSe₃ exhibits superconductivity below 2 K (−271 °C).

Niobium triselenide has been considered as a cathode material for rechargeable lithium batteries due to its fibrous structure, high electrical conductivity, and high gravimetric and volumetric energy densities at room temperature.^[7]

References

^ Monçeau, P.; Ong, N.; Portis, A.; Meerschaut, A.; Rouxel, J. (1976). "Electric Field Breakdown of Charge-Density-Wave—Induced Anomalies in NbSe₃". Physical Review Letters. 37 (10): 602. Bibcode:1976PhRvL..37..602M. doi:10.1103/PhysRevLett.37.602.
^ Hoffmann, Roald; Shaik, Sason; Scott, J.C.; Whangbo, Myung-Hwan; Foshee, Mary J. (September 1980). "The electronic structure of NbSe3" (PDF). Journal of Solid State Chemistry. 34 (2): 263–269. Bibcode:1980JSSCh..34..263H. doi:10.1016/0022-4596(80)90230-3.
^ Gor'kov, L. P.; Grüner, G., eds. (1985). "Transition Metal Trichalcogenides". Modern Problems in Condensed Matter Science [Charge Density Waves in Solids]. Vol. 25. North-Holland: Elsevier Science Publishers B.V. ISBN 0-444-87370-8.
^ Hodeau, J.L.; Marezio, M.; Roucau, C.; Ayroles, R.; Meerschaut, A.; Rouxel, J.; Monceau, P. (1978). "Charge Density Waves in NbSe₃ at 145 K: Crystal structures x-ray and Electron Diffraction Studies". Journal of Physics C. 11 (20): 4117–4134. Bibcode:1978JPhC...11.4117H. doi:10.1088/0022-3719/11/20/009.
^ Tang, H.; Li, C.; Yang, X.; Mo, C.; Cao, K.; Yan, F. (2011). "Synthesis and tribological properties of NbSe3 nanofibers and NbSe2 microsheets". Crystal Research and Technology. 46 (4): 400. doi:10.1002/crat.201100030. S2CID 96226495.
^ Hodeau, J. L.; Marezio, M.; Roucau, C.; Ayroles, R.; Meerschaut, A.; Rouxel, J.; Monceau, P. (1978). "Charge-density waves in NbSe3 at 145K: Crystal structures, X-ray and electron diffraction studies". Journal of Physics C: Solid State Physics. 11 (20): 4117. Bibcode:1978JPhC...11.4117H. doi:10.1088/0022-3719/11/20/009.
^ Ratnakumar, B. V.; Stefano, S.; Bankston, C. P. (1989). "A.c. Impedance of niobium triselenide cathode in secondary lithium cells". Journal of Applied Electrochemistry. 19 (6): 813. doi:10.1007/BF01007927. S2CID 98476675.