Niobium oxide

Niobium oxide (N2O5), also named as niobium pentoxide, is used in metallurgy to produce hard materials. Niobium pentoxide is added to the glass during the production of optical lenses to make the lenses lighter, thinner and with greater resilience. At the same time, niobium pentoxide increases the refractive index of optical glasses. In electronics, niobium pentoxide is used to produce multi-layered ceramic capacitors with high capacity and for the preparation of electroacoustic or electrooptical components such as LiNbO3 and KNbO3 or ferroelectric ceramics such as Pb(Mg1/3Nb2/3)O3. It is further used in making cathodes, as pigment in printing, packaging and solid fuels, in food processing industry as dietary supplements, and in the production of powder metallurgy products.

Niobium(V) oxide is a white crystalline powder that turns light yellow upon exposure to oxygen. It is insoluble in water and most acids but soluble in molten potassium hydrogen sulfate or alkali metal carbonate and hydroxide.

Its hydrate has the chemical formula Nb₂O₅·xH₂O. It decomposes upon heating and is soluble in concentrated sulphuric acid, concentrated hydrochloric acid, hydrofluoric acid, and strong acids. It is insoluble in water and ammonia solution. It can be obtained by calcining metallic niobium in air or by dehydrating niobium oxide.

Niobium(V) oxide (Nb₂O₅) is a white orthogonal crystals which transforms from an amorphous state to crystalline form upon heating to 380–435°C. At 400–500°C, the presence of oxygen vacancies within the crystal lattice causes it to turn a pale yellow colour (similar to that of zinc oxide). 

Nb₂O₅ exhibits multiple crystalline forms, with phase transitions governed by factors including starting material, pressure, and temperature. Over ten common crystal structures exist: monoclinic systems (B, H, N, R, and Z phases); tetragonal systems (P and M phases); orthorhombic systems (T phase); and hexagonal systems (TT phase).

Niobium(V) oxide is the precursor to a majority of niobium compounds, powder metallurgy products and alloys. It is also used in glass, optic and ceramic applications. The nanoparticles of niobium pentoxide are useful in the preparation of electrochemical capacitors and cathodes. In addition, appropriate preparations of this compound can be used as a dietary supplement in the food industry. It is a precursor to lithium niobate which finds extensive use in piezoelectric sensors, anti-aliasing filters, optical waveguides, mobile phones, surface acoustic devices, optical modulators including linear and non-linear optical applications.

Niobium(V) oxide is used in metallurgy, electronics, optics, and the production of hard materials.
Applied in the solid state formation of an unusual cation deficient perovskite, Ba7Nb4MoO20.
Promising results were obtained using niobium(V) oxide as an alternate electrode to lithium metal in advanced fuel cells.
Niobium Oxide (Nb2O5) is a new electrode material with pseudocapacitive charge storage being introduced to the market for the first time as a potential anode material.

Niobium pentoxide is produced as an intermediate during recovery of Nb metal from ores (See niobium).
Also, the pentoxide may be produced by igniting niobium metal powder, niobium carbide, or niobium fluoride in oxygen.

Niobium pentoxide (Nb2O5) increases both the refractive index of optical glasses and the capacity of multi-layered ceramic capacitors (MLCCs). In contrast to lead oxide, niobium pentoxide poses no health risks.

Non flammable

The screening level for niobium oxide is 0.1 μg/m3 based on annual averaging.

[1] https://www.azonano.com/article.aspxArticleID=3405
[2] https://en.wikipedia.org/wiki/Niobium_pentoxide
[3] https://www.hcstarck.com
[4] Michel A. Aegerter, Michael Schmitt, and Yeping Guo, Sol-gel niobium pentoxide coatings: Applications to photovoltaic energy conversion and electrochromism, International Journal of Photoenergy, 2002, vol. 4
[5] https://pubchem.ncbi.nlm.nih.gov
[6] I. RYSHCHENKO. Electrochemical Synthesis of Crystalline Niobium Oxide[J]. Materials Science Forum, 2021, 182 1 1: 51-60. DOI:10.4028/www.scientific.net/MSF.1038.51.
[7] SCOTT B. FICARRO. Niobium(V) Oxide (Nb2O5): Application to Phosphoproteomics[J]. Analytical Chemistry, 2008, 80 12: 4606-4613. DOI:10.1021/ac800564h.