Editing Zirconium (section)

==Characteristics==
[[Image:Zirconium rod.jpg|thumb|Zirconium rod]]
<section begin=properties />Zirconium is a [[luster (mineralogy)|lustrous]], greyish-white, soft, ductile, malleable metal that is solid at room temperature, though it is hard and [[brittle]] at lesser purities.<ref name="nbb" /> In powder form, zirconium is highly flammable, but the solid form is much less prone to ignition. Zirconium is highly resistant to corrosion by alkalis, acids, salt water and other agents.<ref name="CRC2008" /> However, it will dissolve in [[hydrochloric acid|hydrochloric]] and [[sulfuric acid]], especially when [[fluorine]] is present.<ref name="Nostrand">{{cite book|contribution=Zirconium|date=2005|title=Van Nostrand's Encyclopedia of Chemistry |editor-last= Considine |editor-first= Glenn D.|pages=1778–1779|place=New York|publisher=Wylie-Interscience|isbn=978-0-471-61525-5}}</ref> [[Alloy]]s with [[zinc]] are [[magnetism|magnetic]] at less than 35&nbsp;K.<ref name="CRC2008" /><section end=properties />

The [[melting point]] of zirconium is 1855&nbsp;°C (3371&nbsp;°F), and the [[boiling point]] is 4409&nbsp;°C (7968&nbsp;°F).<ref name="CRC2008">{{cite book|contribution=Zirconium|date=2007–2008|title=CRC Handbook of Chemistry and Physics|editor-last=Lide|editor-first=David R.|volume=4|page=42|place=New York|publisher=CRC Press|isbn=978-0-8493-0488-0}}</ref> Zirconium has an [[electronegativity]] of 1.33 on the Pauling scale. Of the elements within the [[d-block]] with known electronegativities, zirconium has the fourth lowest electronegativity after [[hafnium]], [[yttrium]], and [[lutetium]].<ref>{{cite web|last=Winter|first=Mark|title=Electronegativity (Pauling)|publisher=University of Sheffield |date= 2007 |url= https://www.webelements.com/periodicity/eneg_pauling/heatscape.html |access-date= 2024-07-27}}</ref>

At room temperature zirconium exhibits a hexagonally close-packed crystal structure, α-Zr, which changes to β-Zr, a body-centered cubic crystal structure, at 863&nbsp;°C. Zirconium exists in the β-phase until the melting point.<ref>{{cite journal|author=Schnell I|author2=Albers RC|name-list-style=amp|title=Zirconium under pressure: phase transitions and thermodynamics|journal=Journal of Physics: Condensed Matter|volume=18|pages=16 |date=January 2006|doi=10.1088/0953-8984/18/5/001|issue=5|bibcode= 2006JPCM...18.1483S|s2cid=56557217}}</ref>

===Isotopes===
{{Main|Isotopes of zirconium}}

Naturally occurring zirconium is composed of five isotopes. <sup>90</sup>Zr, <sup>91</sup>Zr, <sup>92</sup>Zr and <sup>94</sup>Zr are stable, although <sup>94</sup>Zr is predicted to undergo [[double beta decay]] (not observed experimentally) with a [[half-life]] of more than 1.10×10<sup>17</sup>&nbsp;years. <sup>96</sup>Zr has a half-life of 2.34×10<sup>19</sup>&nbsp;years, and is the longest-lived radioisotope of zirconium. Of these natural isotopes, <sup>90</sup>Zr is the most common, making up 51.45% of all zirconium. <sup>96</sup>Zr is the least common, comprising only 2.80% of zirconium.{{NUBASE2020|ref}}

Thirty-three artificial isotopes of zirconium have been synthesized, ranging in atomic mass from 77 to 114.{{NUBASE2020|ref}}<ref>{{Cite journal|url=https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.014614|doi = 10.1103/PhysRevC.103.014614|title = Observation of new neutron-rich isotopes in the vicinity of Zr110|year = 2021|last1 = Sumikama|first1 = T.|last2 = Fukuda|first2 = N.|last3 = Inabe|first3 = N.|last4 = Kameda|first4 = D.|last5 = Kubo|first5 = T.|last6 = Shimizu|first6 = Y.|last7 = Suzuki|first7 = H.|last8 = Takeda|first8 = H.|last9 = Yoshida|first9 = K.|last10 = Baba|first10 = H.|last11 = Browne|first11 = F.|last12 = Bruce|first12 = A. M.|last13 = Carroll|first13 = R.|last14 = Chiga|first14 = N.|last15 = Daido|first15 = R.|last16 = Didierjean|first16 = F.|last17 = Doornenbal|first17 = P.|last18 = Fang|first18 = Y.|last19 = Gey|first19 = G.|last20 = Ideguchi|first20 = E.|last21 = Isobe|first21 = T.|last22 = Lalkovski|first22 = S.|last23 = Li|first23 = Z.|last24 = Lorusso|first24 = G.|last25 = Lozeva|first25 = R.|last26 = Nishibata|first26 = H.|last27 = Nishimura|first27 = S.|last28 = Nishizuka|first28 = I.|last29 = Odahara|first29 = A.|last30 = Patel|first30 = Z.|journal = Physical Review C|volume = 103| issue=1 | page=014614 | bibcode=2021PhRvC.103a4614S |s2cid = 234019083|display-authors = 1|hdl = 10261/260248|hdl-access = free}}</ref> [[Zirconium-93|<sup>93</sup>Zr]] is the longest-lived artificial isotope, with a half-life of 1.61×10<sup>6</sup>&nbsp;years. Radioactive isotopes at or above mass number 93 decay by [[beta decay|electron emission]], whereas those at or below 89 decay by [[beta decay|positron emission]]. The only exception is <sup>88</sup>Zr, which decays by [[electron capture]].{{NUBASE2020|ref}}

Thirteen isotopes of zirconium also exist as [[nuclear isomer|metastable isomers]]: <sup>83m1</sup>Zr, <sup>83m2</sup>Zr, <sup>85m</sup>Zr, <sup>87m</sup>Zr, <sup>88m</sup>Zr, <sup>89m</sup>Zr, <sup>90m1</sup>Zr, <sup>90m2</sup>Zr, <sup>91m</sup>Zr, <sup>97m</sup>Zr, <sup>98m</sup>Zr, <sup>99m</sup>Zr, and <sup>108m</sup>Zr. Of these, <sup>97m</sup>Zr has the shortest half-life at 104.8&nbsp;nanoseconds. <sup>89m</sup>Zr is the longest lived with a half-life of 4.161&nbsp;minutes.{{NUBASE2020|ref}}

===Occurrence===
{{Category see also|Zirconium minerals}}
[[File:Zirconium mineral concentrates - world production trend.svg|thumb|World production trend of zirconium mineral concentrates|upright=1.1|left]]
Zirconium has a concentration of about 130&nbsp;mg/kg within the [[abundance of elements in Earth's crust|Earth's crust]] and about 0.026&nbsp;μg/L in [[sea water]]. It is the 18th most abundant element in the crust.<ref name="argonne" /> It is not found in nature as a [[native metal]], reflecting its intrinsic instability with respect to water. The principal commercial source of zirconium is [[zircon]] (ZrSiO<sub>4</sub>), a [[silicate mineral]],<ref name="nbb" /> which is found primarily in Australia, Brazil, India, Russia, South Africa and the United States, as well as in smaller deposits around the world.<ref name="madehow" /> As of 2013, two-thirds of zircon mining occurs in Australia and South Africa.<ref name="nbb13">{{cite web|title=Zirconium and Hafnium – Mineral resources|date=2014|url=http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2014-zirco.pdf}}</ref> Zircon resources exceed 60 million [[tonne]]s worldwide<ref name="usgs2008">{{cite journal |title= Zirconium and Hafnium |journal= Mineral Commodity Summaries |pages= 192–193 |date=January 2008 |url=http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2008-zirco.pdf |access-date= 2008-02-24}}</ref> and annual worldwide zirconium production is approximately 900,000 tonnes.<ref name="argonne">{{cite book|first1=John|last1=Peterson|first2=Margaret|last2=MacDonell|contribution=Zirconium|title=Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas|date=2007|pages=64–65|publisher=Argonne National Laboratory|url=http://www.evs.anl.gov/pub/doc/ANL_ContaminantFactSheets_All_070418.pdf|access-date=2008-02-26|url-status=dead|archive-url=https://web.archive.org/web/20080528130257/http://www.evs.anl.gov/pub/doc/ANL_ContaminantFactSheets_All_070418.pdf|archive-date=2008-05-28}}</ref> Zirconium also occurs in more than 140 other minerals, including the commercially useful ores [[baddeleyite]] and [[eudialyte]].<ref>{{cite web|author=Ralph, Jolyon|author2=Ralph, Ida|name-list-style=amp |title=Minerals that include Zr|publisher=Mindat.org |date=2008|url=http://www.mindat.org/chemsearch.php?inc=Zr%2C&exc=&sub=Search+for+Minerals|access-date=2008-02-23}}</ref>

Zirconium is relatively abundant in [[stellar classification #Class S|S-type stars]], and has been detected in the sun and in meteorites. Lunar rock samples brought back from several [[Apollo program|Apollo]] missions to the moon have a high zirconium oxide content relative to terrestrial rocks.<ref>{{Cite journal |last1=Peckett |first1=A. |last2=Phillips |first2=R. |last3=Brown |first3=G. M. |date=March 1972 |title=New Zirconium-rich Minerals from Apollo 14 and 15 Lunar Rocks |url=https://www.nature.com/articles/236215a0 |journal=Nature |language=en |volume=236 |issue=5344 |pages=215–217 |doi=10.1038/236215a0 |bibcode=1972Natur.236..215P |issn=0028-0836}}</ref>

[[EPR spectroscopy]] has been used in investigations of the unusual 3+ valence state of zirconium. The EPR spectrum of Zr<sup>3+</sup>, which has been initially observed as a parasitic signal in Fe‐doped single crystals of ScPO<sub>4</sub>, was definitively identified by preparing single crystals of ScPO<sub>4</sub> doped with isotopically enriched (94.6%)<sup>91</sup>Zr. Single crystals of LuPO<sub>4</sub> and YPO<sub>4</sub> doped with both naturally abundant and isotopically enriched Zr have also been grown and investigated.<ref>{{Cite journal|last1=Abraham|first1=M. M.|last2=Boatner|first2=L. A.|last3=Ramey|first3=J. O.|last4=Rappaz|first4=M.|date=1984-12-20|title=The occurrence and stability of trivalent zirconium in orthophosphate single crystals|url=https://aip.scitation.org/doi/abs/10.1063/1.447678|journal=The Journal of Chemical Physics|volume=81|issue=12|pages=5362–5366|doi=10.1063/1.447678|bibcode=1984JChPh..81.5362A|issn=0021-9606}}</ref>