Editing Niobium (section)

===Physical===
Niobium is a [[lustre (mineralogy)|lustrous]], grey, [[ductility|ductile]], [[paramagnetism|paramagnetic]] [[metal]] in [[Group 5 element|group 5]] of the [[periodic table]] (see table), with an electron configuration in the outermost [[electron shell|shells]] atypical for group 5. Similarly atypical configurations occur in the neighborhood of [[ruthenium]] (44) and [[rhodium]] (45).<ref>{{Cite journal |last=Scerri |first=Eric R. |date=April 2019 |title=Five ideas in chemical education that must die |url=http://link.springer.com/10.1007/s10698-018-09327-y |journal=Foundations of Chemistry |language=en |volume=21 |issue=1 |pages=61–69 |doi=10.1007/s10698-018-09327-y |issn=1386-4238}}</ref>

{| class="wikitable"  style="margin:10px; float:right;"
|-
![[Atomic number|Z]] !! [[Chemical element|Element]] !! [[Electron shell|No. of electrons/shell]]
|-
| 23 || [[vanadium]] || 2, 8, 11, 2
|-
| 41 || niobium || 2, 8, 18, 12, 1
|-
| 73 || [[tantalum]] || 2, 8, 18, 32, 11, 2
|-
| 105 || [[dubnium]] || 2, 8, 18, 32, 32, 11, 2
|}

Although it is thought to have a [[body-centered cubic]] crystal structure from absolute zero to its melting point, high-resolution measurements of the thermal expansion along the three crystallographic axes reveal anisotropies which are inconsistent with a cubic structure.<ref>{{cite journal |last1=Bollinger |first1=R. K. |last2=White |first2=B. D. |last3=Neumeier |first3=J. J. |last4=Sandim |first4=H. R. Z. |last5=Suzuki |first5=Y. |last6=dos Santos |first6=C. A. M. |last7=Avci |first7=R. |last8=Migliori |first8=A. |last9=Betts |first9=J. B. |date=2011 |title=Observation of a Martensitic Structural Distortion in V, Nb, and Ta |journal=Physical Review Letters |volume=107 |issue=7 |pages=075503 |doi=10.1103/PhysRevLett.107.075503 |bibcode=2011PhRvL.107g5503B |pmid=21902404|doi-access=free }}</ref> Therefore, further research and discovery in this area is expected.

Niobium becomes a [[superconductor]] at [[cryogenics|cryogenic]] temperatures. At atmospheric pressure, it has the highest critical temperature of the elemental superconductors at 9.2&nbsp;[[Kelvin|K]].<ref name="Pein">{{cite journal|title = A Superconducting Nb<sub>3</sub>Sn Coated Multicell Accelerating Cavity|first = M.|last = Peiniger|author2=Piel, H. |journal = IEEE Transactions on Nuclear Science|date= 1985|volume= 32|issue = 5|doi = 10.1109/TNS.1985.4334443|pages = 3610–3612|bibcode = 1985ITNS...32.3610P |s2cid = 23988671}}</ref> Niobium has the greatest [[superconductor#Meissner effect|magnetic penetration depth]] of any element.<ref name="Pein" /> In addition, it is one of the three elemental [[Type II superconductor]]s, along with [[vanadium]] and [[technetium]]. The superconductive properties are strongly dependent on the purity of the niobium metal.<ref name="Moura">{{cite journal|title=Melting And Purification of Niobium|first=Hernane R.|last = Salles Moura|author2=Louremjo de Moura, Louremjo |journal=AIP Conference Proceedings|volume=927|date=2007|issue=927|pages=165–178|doi=10.1063/1.2770689|bibcode=2007AIPC..927..165M}}</ref>

When very pure, it is comparatively soft and ductile, but impurities make it harder.<ref name="Nowak" /><!--awkward; this either contains redundancy or is leaving something out-->

The metal has a low [[Neutron capture#Capture cross section|capture cross-section]] for thermal [[neutron]]s;<ref>{{cite journal|title = Columbium Alloys Today|author=Jahnke, L. P.|author2=Frank, R. G.|author3=Redden, T. K.|date = 1960|journal = Metal Progr.|volume = 77|issue = 6|pages = 69–74|osti = 4183692}}</ref> thus it is used in the nuclear industries where neutron transparent structures are desired.<ref>{{cite journal|first = A. V.|last = Nikulina|title = Zirconium-Niobium Alloys for Core Elements of Pressurized Water Reactors|journal = Metal Science and Heat Treatment|volume = 45|issue = 7–8|date = 2003|doi = 10.1023/A:1027388503837|pages = 287–292|bibcode = 2003MSHT...45..287N|s2cid = 134841512}}</ref>