Niobium pentoxide

Niobium pentoxide
Names
	IUPAC name Niobium(V) oxide
	Other names Niobium pentoxide
Identifiers
CAS Number	1313-96-8 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.013.831
PubChem CID	123105;
UNII	K9343U17IN ;
CompTox Dashboard (EPA)	DTXSID20893850 ;
	SMILES O=[Nb](=O)O[Nb](=O)=O;
Properties
Chemical formula	Nb2O5
Molar mass	265.81 g/mol
Appearance	white orthogonal solid
Density	4.60 g/cm3
Melting point	1,512 °C (2,754 °F; 1,785 K)
Solubility in water	insoluble
Solubility	soluble in HF
Magnetic susceptibility (χ)	-10·10−6 cm3/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Niobium pentoxide is the inorganic compound with the formula Nb₂O₅. A colorless, insoluble, and fairly unreactive solid, it is the most widespread precursor for other compounds and materials containing niobium. It is predominantly used in alloying, with other specialized applications in capacitors, optical glasses, and the production of lithium niobate.^[2]

Structure

It has many polymorphic forms all based largely on octahedrally coordinated niobium atoms.^[3]^[4] The polymorphs are identified with a variety of prefixes.^[3]^[4] The form most commonly encountered is monoclinic H-Nb₂O₅, which has a complex structure with a unit cell containing 28 niobium atoms and 70 oxygen, where 27 of the niobium atoms are octahedrally coordinated and one tetrahedrally.^[5] There is an uncharacterised solid hydrate, Nb₂O₅·nH₂O, the so-called niobic acid (previously called columbic acid), which can be prepared by hydrolysis of a basic solution of niobium pentachloride or Nb₂O₅ dissolved in HF.^[6]

Molten niobium pentoxide has lower mean coordination numbers than the crystalline forms, with a structure comprising mostly NbO₅ and NbO₆ polyhedra.^[7]

Production

Hydrolysis

Nb₂O₅ is prepared by hydrolysis of alkali-metal niobates, alkoxides or fluoride using base. Such ostensibly simple procedures afford hydrated oxides that can then be calcined. Pure Nb₂O₅ can also be prepared by hydrolysis of NbCl₅:^[8]

2 NbCl₅ + 5 H₂O → Nb₂O₅ + 10 HCl

A method of production via sol-gel techniques has been reported hydrolysing niobium alkoxides in the presence of acetic acid, followed by calcination of the gels to produce the orthorhombic form,^[3] T-Nb₂O₅.^[9]

Oxidation

Given that Nb₂O₅ is the most common and robust compound of niobium, many methods, both practical and esoteric, exist for its formation. The oxide for example, arises when niobium metal is oxidised in air.^[10] The oxidation of niobium dioxide, NbO₂ in air forms the polymorph, L-Nb₂O₅.^[11]

Nano-sized niobium pentoxide particles have been synthesized by LiH reduction of NbCl₅, followed by aerial oxidation as part of a synthesis of nano structured niobates.^{[citation needed]}

Reactions

Nb₂O₅ is attacked by HF and dissolves in fused alkali.^[6]^[10]

Reduction to the metal

The conversion of Nb₂O₅ is the main route for the industrial production of niobium metal. In the 1980s, about 15,000,000 kg of Nb₂O₅ were consumed annually for reduction to the metal.^[12] The main method is reduction of this oxide with aluminium:

3 Nb₂O₅ + 10 Al → 6 Nb + 5 Al₂O₃

An alternative but less practiced route involves carbothermal reduction, which proceeds via reduction with carbon and forms the basis of the two stage Balke process:^[13]^[14]

Nb₂O₅ + 7 C → 2 NbC + 5 CO (heated under vacuum at 1800 °C)

5 NbC + Nb₂O₅ → 7 Nb + 5 CO

Conversion to halides

Many methods are known for conversion of Nb₂O₅ to the halides. The main problem is incomplete reaction to give the oxyhalides. In the laboratory, the conversion can be effected with thionyl chloride:^[15]

Nb₂O₅ + 5 SOCl₂ → 2 NbCl₅ + 5 SO₂

Nb₂O₅ reacts with CCl₄ to give niobium oxychloride NbOCl₃.

Conversion to niobates

Treating Nb₂O₅ with aqueous NaOH at 200 °C can give crystalline sodium niobate, NaNbO₃ whereas the reaction with KOH may yield soluble Lindqvist-type hexaniobates, Nb
₆O⁸⁻
₁₉.^[16] Lithium niobates such as LiNbO₃ and Li₃NbO₄ can be prepared by reaction lithium carbonate and Nb₂O₅.^[17]^[18]

Conversion to reduced niobium oxides

High temperature reduction with H₂ gives NbO₂:^[10]

Nb₂O₅ + H₂ → 2 NbO₂ + H₂O

Niobium monoxide arises from a comproportionation using an arc-furnace:^[19]

Nb₂O₅ + 3Nb → 5 NbO

The burgundy-coloured niobium(III) oxide, one of the first superconducting oxides, can be prepared again by an comproportionation:^[18]

Li₃NbO₄ + 2 NbO → 3 LiNbO₂

Uses

Niobium pentoxide is used mainly in the production of niobium metal,^[12] but specialized applications exist in the production of optical glasses and lithium niobate.^[2]

Thin films of Nb₂O₅ form the dielectric layers in niobium electrolytic capacitors.

Nb₂O₅ have been considered for use as an anode in a lithium-ion battery, given that their ordered crystalline structure allows charging speeds of 225 mAh g⁻¹ at 200 mA g⁻¹ across 400 cycles, at a Coulombic efficiency of 99.93%.^[20]

External links

Basic Niobium Information and Research Data

References

^ "Handbook of Chemistry and Physics 102nd Edition". CRC Press.
^ ^a ^b Francois Cardarelli (2008) Materials Handbook Springer London ISBN 978-1-84628-668-1
^ ^a ^b ^c C. Nico; et al. (2011). "Sintered NbO powders for electronic device applications". The Journal of Physical Chemistry C. 115 (11): 4879–4886. doi:10.1021/jp110672u.
^ ^a ^b Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
^ Gatehouse, B. M.; Wadsley, A. D. (1964-12-01). "The crystal structure of the high temperature form of niobium pentoxide". Acta Crystallographica. 17 (12). International Union of Crystallography (IUCr): 1545–1554. doi:10.1107/s0365110x6400384x. ISSN 0365-110X.
^ ^a ^b D.A. Bayot and M.M. Devillers, Precursors routes for the preparation of Nb based multimetallic oxides in Progress in Solid State Chemistry Research, Arte M. Newman, Ronald W. Buckley, (2007),Nova Publishers, ISBN 1-60021-313-8
^ Alderman, O. L. G. Benmore, C. J. Neuefeind, J. C. Coillet, E Mermet, Alain Martinez, V. Tamalonis, A. Weber, J. K. R. (2018). "Amorphous tantala and its relationship with the molten state". Physical Review Materials. 2 (4): 043602. Bibcode:2018PhRvM...2d3602A. doi:10.1103/PhysRevMaterials.2.043602.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Process for the manufacture of niobium pentoxide or tantalum pentoxide, Kern, Therwil, Jacob, Hooper (CIBA Switzerland), US Patent number: 3133788, (1964)
^ Griesmar, P.; Papin, G.; Sanchez, C.; Livage, J. (1991). "Sol-gel route to niobium pentoxide". Chemistry of Materials. 3 (2). American Chemical Society (ACS): 335–339. doi:10.1021/cm00014a026. ISSN 0897-4756.
^ ^a ^b ^c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ Vezzoli, G. C. (1982-10-01). "Electrical properties of NbO2andNb2O5at elevated temperature in air and flowing argon". Physical Review B. 26 (7). American Physical Society (APS): 3954–3957. Bibcode:1982PhRvB..26.3954V. doi:10.1103/physrevb.26.3954. ISSN 0163-1829.
^ ^a ^b Albrecht, Sven; Cymorek, Christian; Eckert, Joachim (2011), Ullmann's Encyclopedia of Industrial Chemistry: Niobium and Niobium Compounds, Weinheim: Wiley-VCH, doi:10.1002/14356007.a17_251.pub2
^ Alan E. Comyns (1999) Encyclopedic Dictionary of Named Processes in Chemical Technology CRC Press, ISBN 0-8493-1205-1
^ U.S. Environmental Protection Agency, Development Document for Effluent Limitations, Guidelines and Standards for the Nonferrous Metals Manufacturing Point Source Category, Volume VIII, Office of Water Regulations and Standards, May 1989
^ Brown, D. (1967). "Niobium(V) Chloride and Hexachloroniobates(V)". Inorganic Syntheses. Inorganic Syntheses. Vol. 9. pp. 88–92. doi:10.1002/9780470132401.ch24. ISBN 9780470132401.
^ Santos, I.C.M.S.; Loureiro, L.H.; Silva, M.F.P.; Cavaleiro, Ana M.V. (2002). "Studies on the hydrothermal synthesis of niobium oxides". Polyhedron. 21 (20). Elsevier BV: 2009–2015. doi:10.1016/s0277-5387(02)01136-1. ISSN 0277-5387.
^ US Patent 5482001 - Process for producing lithium niobate single crystal,1996, Katoono T., Tominaga H.,
^ ^a ^b Geselbracht, Margret J.; Stacy, Angelica M.; Rosseinsky, Matthew (2007-01-05). "Lithium Niobium Oxide: LiNbO₂ and Superconducting Li_xNbO₂". Inorganic Syntheses. Vol. 30. Hoboken, NJ, USA: John Wiley & Sons, Inc. pp. 222–226. doi:10.1002/9780470132616.ch42. ISBN 9780470132616. ISSN 1934-4716.
^ Reed, T. B.; Pollard, E. R.; Lonney, L. E.; Loehman, R. E.; Honig, J. M. (2007-01-05). "Niobium Monoxide". Inorganic Syntheses. Vol. 30. Hoboken, NJ, USA: John Wiley & Sons, Inc. pp. 108–110. doi:10.1002/9780470132616.ch22. ISBN 9780470132616. ISSN 1934-4716.
^ Lavars, Nick (2022-09-09). "Battery electrode transforms during use for faster charging". New Atlas. Retrieved 2022-09-10.

[1] "Handbook of Chemistry and Physics 102nd Edition". CRC Press.

[Cardarelli-2] Francois Cardarelli (2008) Materials Handbook Springer London ISBN 978-1-84628-668-1

[Nico-3] C. Nico; et al. (2011). "Sintered NbO powders for electronic device applications". The Journal of Physical Chemistry C. 115 (11): 4879–4886. doi:10.1021/jp110672u.

[Wells-4] Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6

[5] Gatehouse, B. M.; Wadsley, A. D. (1964-12-01). "The crystal structure of the high temperature form of niobium pentoxide". Acta Crystallographica. 17 (12). International Union of Crystallography (IUCr): 1545–1554. doi:10.1107/s0365110x6400384x. ISSN 0365-110X.

[Bayot-6] D.A. Bayot and M.M. Devillers, Precursors routes for the preparation of Nb based multimetallic oxides in Progress in Solid State Chemistry Research, Arte M. Newman, Ronald W. Buckley, (2007),Nova Publishers, ISBN 1-60021-313-8

[7] Alderman, O. L. G. Benmore, C. J. Neuefeind, J. C. Coillet, E Mermet, Alain Martinez, V. Tamalonis, A. Weber, J. K. R. (2018). "Amorphous tantala and its relationship with the molten state". Physical Review Materials. 2 (4): 043602. Bibcode:2018PhRvM...2d3602A. doi:10.1103/PhysRevMaterials.2.043602.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[8] Process for the manufacture of niobium pentoxide or tantalum pentoxide, Kern, Therwil, Jacob, Hooper (CIBA Switzerland), US Patent number: 3133788, (1964)

[9] Griesmar, P.; Papin, G.; Sanchez, C.; Livage, J. (1991). "Sol-gel route to niobium pentoxide". Chemistry of Materials. 3 (2). American Chemical Society (ACS): 335–339. doi:10.1021/cm00014a026. ISSN 0897-4756.

[Greenwood-10] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[11] Vezzoli, G. C. (1982-10-01). "Electrical properties of NbO2andNb2O5at elevated temperature in air and flowing argon". Physical Review B. 26 (7). American Physical Society (APS): 3954–3957. Bibcode:1982PhRvB..26.3954V. doi:10.1103/physrevb.26.3954. ISSN 0163-1829.

[Ullmann-12] Albrecht, Sven; Cymorek, Christian; Eckert, Joachim (2011), Ullmann's Encyclopedia of Industrial Chemistry: Niobium and Niobium Compounds, Weinheim: Wiley-VCH, doi:10.1002/14356007.a17_251.pub2

[13] Alan E. Comyns (1999) Encyclopedic Dictionary of Named Processes in Chemical Technology CRC Press, ISBN 0-8493-1205-1

[14] U.S. Environmental Protection Agency, Development Document for Effluent Limitations, Guidelines and Standards for the Nonferrous Metals Manufacturing Point Source Category, Volume VIII, Office of Water Regulations and Standards, May 1989

[15] Brown, D. (1967). "Niobium(V) Chloride and Hexachloroniobates(V)". Inorganic Syntheses. Inorganic Syntheses. Vol. 9. pp. 88–92. doi:10.1002/9780470132401.ch24. ISBN 9780470132401.

[16] Santos, I.C.M.S.; Loureiro, L.H.; Silva, M.F.P.; Cavaleiro, Ana M.V. (2002). "Studies on the hydrothermal synthesis of niobium oxides". Polyhedron. 21 (20). Elsevier BV: 2009–2015. doi:10.1016/s0277-5387(02)01136-1. ISSN 0277-5387.

[17] US Patent 5482001 - Process for producing lithium niobate single crystal,1996, Katoono T., Tominaga H.,

[Li3NbO4-18] Geselbracht, Margret J.; Stacy, Angelica M.; Rosseinsky, Matthew (2007-01-05). "Lithium Niobium Oxide: LiNbO₂ and Superconducting Li_xNbO₂". Inorganic Syntheses. Vol. 30. Hoboken, NJ, USA: John Wiley & Sons, Inc. pp. 222–226. doi:10.1002/9780470132616.ch42. ISBN 9780470132616. ISSN 1934-4716.

[19] Reed, T. B.; Pollard, E. R.; Lonney, L. E.; Loehman, R. E.; Honig, J. M. (2007-01-05). "Niobium Monoxide". Inorganic Syntheses. Vol. 30. Hoboken, NJ, USA: John Wiley & Sons, Inc. pp. 108–110. doi:10.1002/9780470132616.ch22. ISBN 9780470132616. ISSN 1934-4716.

[20] Lavars, Nick (2022-09-09). "Battery electrode transforms during use for faster charging". New Atlas. Retrieved 2022-09-10.

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Niobium pentoxide

Structure

Production

Hydrolysis

Oxidation

Reactions

Reduction to the metal

Conversion to halides

Conversion to niobates

Conversion to reduced niobium oxides

Uses

External links

References

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