Editing Tungsten (section)

===Physical properties===
In its raw form, tungsten is a hard steel-grey [[metal]] that is often [[brittle]] and hard to [[metalworking|work]]. Purified, monocrystalline tungsten retains its [[hardness]] (which exceeds that of many steels), and becomes [[malleable]] enough that it can be worked easily.<ref name="albert" /> It is worked by [[forging]], [[drawing (manufacturing)|drawing]], or [[extrusion|extruding]] but it is more commonly formed by [[sintering]]. Sintering is often used due to the very high melting point of tungsten.

Of all metals in pure form, tungsten has the highest [[melting point]] ({{cvt|3422|C|F|disp=comma}}), lowest [[vapor pressure]] (at temperatures above {{cvt|1650|C|F|disp=comma}}), and the highest [[tensile strength]].<ref name="desu">{{cite book| author = Hammond, C. R.| title = The Elements, in Handbook of Chemistry and Physics| edition = 81st| publisher = CRC press| isbn = 978-0-8493-0485-9| date = 2004| url-access = registration| url = https://archive.org/details/crchandbookofche81lide}}</ref> Although [[carbon]] remains solid at higher temperatures than tungsten, carbon [[sublimation (phase transition)|sublimes]] at [[atmospheric pressure]] instead of melting, so it has no melting point. Moreover, tungsten's most stable [[crystal phase]] does not exhibit any high-pressure-induced structural transformations for pressures up to at least 364 gigapascals.<ref>{{Cite journal |last1=McMahon |first1=Malcolm I. |last2=Nelmes |first2=Richard J.|author2-link=Richard Nelmes|date=2006 |title=High-pressure structures and phase transformations in elemental metals |url=http://xlink.rsc.org/?DOI=b517777b |journal=Chemical Society Reviews |language=en |volume=35 |issue=10 |pages=943–963 |doi=10.1039/b517777b |pmid=17003900 |issn=0306-0012}}</ref> Tungsten has the lowest [[coefficient of thermal expansion]] of any pure metal. The low thermal expansion and high melting point and [[tensile strength]] of tungsten originate from strong [[covalent bond]]s<!--YES REALLY, THEY ARE QUITE DIRECTIONAL--> formed between tungsten atoms by the 5d electrons.<ref>{{cite book|url=https://books.google.com/books?id=foLRISkt9gcC&pg=PA9|page=9|title=Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds|author=Lassner, Erik |author2=Schubert, Wolf-Dieter |publisher=Springer|date=1999|isbn=978-0-306-45053-2}}</ref>
Alloying small quantities of tungsten with [[steel]] greatly increases its [[toughness]].<ref name="daintith" />

Tungsten exists in two major [[crystallinity|crystalline]] forms: α and β. The former has a [[body-centered cubic]] structure and is the more stable form. The structure of the [[beta-tungsten|β phase]] is called [[A15 phases|A15 cubic]]; it is [[metastable]], but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar [[Crystal habit|habit]]. The α phase has one third of the [[electrical resistivity]]<ref>Bean, Heather (October 19, 1998). [https://web.archive.org/web/20111023221423/http://users.frii.com/bean/analysis.htm Material Properties and Analysis Techniques for Tungsten Thin Films]. frii.com</ref> and a much lower [[superconductivity|superconducting transition temperature]] T<sub>C</sub> relative to the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate T<sub>C</sub> values.<ref>{{cite journal|title=Tuning of Tungsten Thin Film Superconducting Transition Temperature for Fabrication of Photon Number Resolving Detectors|url=http://mysite.du.edu/~balzar/IEEE-Adriana%20-2005.pdf|author=Lita, A. E.|author2=Rosenberg, D.|author3=Nam, S.|author4=Miller, A.|author5=Balzar, D.|author6=Kaatz, L. M.|author7=Schwall, R. E.|journal=IEEE Transactions on Applied Superconductivity|volume=15|issue=2|pages=3528–3531|doi=10.1109/TASC.2005.849033|date=2005|url-status=live|archive-url=https://web.archive.org/web/20130513015735/http://mysite.du.edu/~balzar/IEEE-Adriana%20-2005.pdf|archive-date=2013-05-13|bibcode=2005ITAS...15.3528L|s2cid=5804011}}</ref><ref>{{Cite journal| doi = 10.1103/PhysRevLett.16.101| volume = 16 | issue = 3| pages = 101–104| last = Johnson| first = R. T.|author2=O. E. Vilches |author3=J. C. Wheatley |author4=Suso Gygax | title = Superconductivity of Tungsten| journal = Physical Review Letters| date = 1966|bibcode = 1966PhRvL..16..101J }}</ref> The T<sub>C</sub> value can also be raised by [[alloy]]ing tungsten with another metal (e.g. 7.9 K for W-[[technetium|Tc]]).<ref>{{Cite journal | doi = 10.1103/PhysRev.140.A1177| volume = 140| issue = 4A| pages = A1177–A1180| last = Autler| first = S. H.|author2=J. K. Hulm |author3=R. S. Kemper | title = Superconducting Technetium–Tungsten Alloys| journal = Physical Review|date = 1965|bibcode = 1965PhRv..140.1177A }}</ref> Such tungsten alloys are sometimes used in low-temperature superconducting circuits.<ref>{{Cite journal | doi = 10.1209/0295-5075/79/57008| volume = 79| page = 57008| last = Shailos| first = A.|author2=W Nativel |author3=A Kasumov |author4=C Collet |author5=M Ferrier |author6=S Guéron |author7=R Deblock |author8=H Bouchiat |author8-link= Hélène Bouchiat | title = Proximity effect and multiple Andreev reflections in few-layer graphene| journal = Europhysics Letters| date = 2007|arxiv = cond-mat/0612058 |bibcode = 2007EL.....7957008S | issue = 5 | s2cid = 119351442}}</ref><ref>{{Cite journal| doi = 10.1103/PhysRevB.72.033414| volume = 72| issue = 3| page = 033414| last = Kasumov| first = A. Yu.| author2 = K. Tsukagoshi| author3 = M. Kawamura| author4 = T. Kobayashi| author5 = Y. Aoyagi| author6 = K. Senba| author7 = T. Kodama| author8 = H. Nishikawa| author9 = I. Ikemoto| author10 = K. Kikuchi| author11 = V. T. Volkov| author12 = Yu. A. Kasumov| author13 = R. Deblock| author14 = S. Guéron| author15 = H. Bouchiat|author15-link= Hélène Bouchiat | title = Proximity effect in a superconductor-metallofullerene-superconductor molecular junction| journal = Physical Review B|date=2005|arxiv = cond-mat/0402312 |bibcode = 2005PhRvB..72c3414K | s2cid = 54624704}}</ref><ref>{{Cite journal
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