Niobium pentoxide

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Niobium pentoxide
Kristallstruktur Niob(V)-oxid.png
Names
IUPAC name
Niobium(V) oxide
Other names
Niobium pentoxide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.013.831 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • O=[Nb](=O)O[Nb](=O)=O
Properties
Nb2O5
Molar mass 265.81 g/mol
Appearancewhite orthogonal solid
Density 4.60 g/cm3
Melting point 1,512 °C (2,754 °F; 1,785 K)
insoluble
Solubility soluble in HF
-10·10−6 cm3/mol [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Niobium pentoxide is the inorganic compound with the formula Nb 2 O 5. 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]

Contents

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-Nb 2 O 5, 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.

Nb 2 O 5 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]

Related Research Articles

<span class="mw-page-title-main">Niobium</span> Chemical element, symbol Nb and atomic number 41

Niobium is a chemical element; it has symbol Nb and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has similar ductility to iron. Niobium oxidizes in Earth's atmosphere very slowly, hence its application in jewelry as a hypoallergenic alternative to nickel. Niobium is often found in the minerals pyrochlore and columbite, hence the former name "columbium". Its name comes from Greek mythology: Niobe, daughter of Tantalus, the namesake of tantalum. The name reflects the great similarity between the two elements in their physical and chemical properties, which makes them difficult to distinguish.

<span class="mw-page-title-main">Group 5 element</span> Group of elements in the periodic table

Group 5 is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. This group is sometimes called the vanadium group or vanadium family after its lightest member; however, the group itself has not acquired a trivial name because it belongs to the broader grouping of the transition metals.

<span class="mw-page-title-main">Praseodymium(III) chloride</span> Chemical compound

Praseodymium(III) chloride is the inorganic compound with the formula PrCl3. Like other lanthanide trichlorides, it exists both in the anhydrous and hydrated forms. It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green heptahydrate.

<span class="mw-page-title-main">Phosphorus pentachloride</span> Chemical compound

Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides/oxychlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride.

<span class="mw-page-title-main">Vanadium(V) oxide</span> Precursor to vanadium alloys and industrial catalyst

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V2O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

<span class="mw-page-title-main">Niobium(V) chloride</span> Chemical compound

Niobium(V) chloride, also known as niobium pentachloride, is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of NbOCl3. It is often used as a precursor to other compounds of niobium. NbCl5 may be purified by sublimation.

<span class="mw-page-title-main">Tantalum(V) chloride</span> Chemical compound

Tantalum(V) chloride, also known as tantalum pentachloride, is an inorganic compound with the formula TaCl5. It takes the form of a white powder and is commonly used as a starting material in tantalum chemistry. It readily hydrolyzes to form tantalum(V) oxychloride (TaOCl3) and eventually tantalum pentoxide (Ta2O5); this requires that it be synthesised and manipulated under anhydrous conditions, using air-free techniques.

<span class="mw-page-title-main">Tetrasulfur tetranitride</span> Chemical compound

Tetrasulfur tetranitride is an inorganic compound with the formula S4N4. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen. It is a precursor to many S-N compounds and has attracted wide interest for its unusual structure and bonding.

<span class="mw-page-title-main">Sodium sulfide</span> Chemical compound

Sodium sulfide is a chemical compound with the formula Na2S, or more commonly its hydrate Na2S·9H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are generally yellow to brick red owing to the presence of polysulfides and commonly supplied as a crystalline mass, in flake form, or as a fused solid. They are water-soluble, giving strongly alkaline solutions. When exposed to moist air, Na2S and its hydrates emit hydrogen sulfide, an extremely toxic, flammable and corrosive gas which smells like rotten eggs.

<span class="mw-page-title-main">Lithium niobate</span> Chemical compound

Lithium niobate is a synthetic salt consisting of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linear and non-linear optical applications. Lithium niobate is sometimes referred to by the brand name linobate.

<span class="mw-page-title-main">Tantalum pentoxide</span> Chemical compound

Tantalum pentoxide, also known as tantalum(V) oxide, is the inorganic compound with the formula Ta
2O
5. It is a white solid that is insoluble in all solvents but is attacked by strong bases and hydrofluoric acid. Ta
2O
5 is an inert material with a high refractive index and low absorption, which makes it useful for coatings. It is also extensively used in the production of capacitors, due to its high dielectric constant.

<span class="mw-page-title-main">Tungsten(IV) oxide</span> Chemical compound

Tungsten(IV) oxide is the chemical compound with the formula WO2. The bronze-colored solid crystallizes in a monoclinic cell. The rutile-like structure features distorted octahedral WO6 centers with alternate short W–W bonds (248 pm). Each tungsten center has the d2 configuration, which gives the material a high electrical conductivity.

<span class="mw-page-title-main">Niobium monoxide</span> Chemical compound

Niobium monoxide is the inorganic compound with the formula NbO. It is a grey solid with metallic conductivity.

<span class="mw-page-title-main">Niobium dioxide</span> Chemical compound

Niobium dioxide, is the chemical compound with the formula NbO2. It is a bluish-black non-stoichiometric solid with a composition range of NbO1.94-NbO2.09. It can be prepared by reducing Nb2O5 with H2 at 800–1350 °C. An alternative method is reaction of Nb2O5 with Nb powder at 1100 °C.

<span class="mw-page-title-main">Niobium oxychloride</span> Chemical compound

Niobium oxychloride is the inorganic compound with the formula NbOCl3. It is a white, crystalline, diamagnetic solid. It is often found as an impurity in samples of niobium pentachloride, a common reagent in niobium chemistry.

<span class="mw-page-title-main">Niobium(V) ethoxide</span> Chemical compound

Niobium(V) ethoxide is an metalorganic compound with formula Nb2(OC2H5)10. It is a colorless liquid that dissolves in some organic solvents but hydrolyzes readily. It is mainly used for the sol-gel processing of materials containing niobium oxides.

Organoniobium chemistry is the chemistry of compounds containing niobium-carbon (Nb-C) bonds. Compared to the other group 5 transition metal organometallics, the chemistry of organoniobium compounds most closely resembles that of organotantalum compounds. Organoniobium compounds of oxidation states +5, +4, +3, +2, +1, 0, -1, and -3 have been prepared, with the +5 oxidation state being the most common.

<span class="mw-page-title-main">Niobium oxalate</span> Chemical compound

Niobium(V) oxalate is the hydrogen oxalate salt of niobium(V). The neutral salt has not been prepared.

Niobium(V) oxynitrate is a chemical compound with the formula NbO(NO3)3. It is a tetragonal white solid that reacts violently with water to produce niobium pentoxide:

A niobate is an oxo-acid salt formed by niobium(V), and the common forms are metaniobate (NbO3−) and orthoniobate (NbO43−). The most common niobates are lithium niobate (LiNbO3) and potassium niobate (KNbO3).

References

  1. ↑ "Handbook of Chemistry and Physics 102nd Edition". CRC Press.
  2. 1 2 Francois Cardarelli (2008) Materials Handbook Springer London ISBN   978-1-84628-668-1
  3. 1 2 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.
  4. 1 2 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. International Union of Crystallography (IUCr). 17 (12): 1545–1554. doi:10.1107/s0365110x6400384x. ISSN   0365-110X.
  6. 1 2 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. American Chemical Society (ACS). 3 (2): 335–339. doi:10.1021/cm00014a026. ISSN   0897-4756.
  10. 1 2 3 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. American Physical Society (APS). 26 (7): 3954–3957. Bibcode:1982PhRvB..26.3954V. doi:10.1103/physrevb.26.3954. ISSN   0163-1829.
  12. 1 2 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. Elsevier BV. 21 (20): 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.,
  18. 1 2 Geselbracht, Margret J.; Stacy, Angelica M.; Rosseinsky, Matthew (2007-01-05). "Lithium Niobium Oxide: LiNbO2 and Superconducting LixNbO2". 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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