View source for Zirconium

{{Short description|Chemical element with atomic number 40}}
{{Distinguish|zircon|Zirconic|Zirconium dioxide{{!}}zirconia|cubic zirconia}}
{{Infobox zirconium}}

'''Zirconium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Zr''' and [[atomic number]] 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous [[transition metal]] with a greyish-white color that closely resembles [[hafnium]] and, to a lesser extent, [[titanium]]. It is solid at room temperature, [[Ductility|ductile]], [[malleable]] and [[corrosion]]-resistant. The name ''zirconium'' is derived from the name of the mineral [[zircon]], the most important source of zirconium. The word is related to [[Persian Language|Persian]] ''[[Jargoon|zargun]]'' (zircon; ''zar-gun'', "gold-like" or "as gold").<ref name=":2">{{OEtymD|zircon}}</ref> Besides zircon, zirconium occurs in over 140 other minerals, including [[baddeleyite]] and [[eudialyte]]; most zirconium is produced as a byproduct of minerals mined for titanium and [[tin]].

Zirconium forms a variety of [[inorganic chemistry|inorganic]] compounds, such as [[zirconium dioxide]], and [[organometallic compounds]], such as [[zirconocene dichloride]]. Five [[isotopes of zirconium|isotopes]] occur naturally, four of which are stable. The metal and its alloys are mainly used as a [[refractory]] and [[opacifier]]; zirconium alloys are used to clad [[nuclear fuel rod]]s due to their low neutron absorption and strong resistance to corrosion, and in space vehicles and turbine blades where high heat resistance is necessary. Zirconium also finds uses in [[Flashbulb (photography)|flashbulbs]], biomedical applications such as [[Dental implant|dental implants]] and [[Prosthesis|prosthetics]], [[deodorant]], and [[water purification]] systems.

Zirconium compounds have no known biological role, though the element is widely distributed in nature and appears in small quantities in biological systems without adverse effects. There is no indication of zirconium as a carcinogen. The main hazards posed by zirconium are flammability in powder form and irritation of the eyes.

==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|page=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, <sup>94</sup>Zr, and <sup>96</sup>Zr. The first four are stable, while <sup>96</sup> is observed to decay with a half-life of 2.34×10<sup>19</sup>&nbsp;years by [[double beta decay|double beta]] emission; this is theoretically possible also for <sup>94</sup>Zr. Of these natural isotopes, <sup>90</sup>Zr is the most common, making up 51.45% of all zirconium, and <sup>96</sup>Zr is the least common, comprising only 2.80%.{{NUBASE2020|ref}}

The artificial [[radioisotope]]s of zirconium known range from <sup>77</sup>Zr to <sup>114</sup>Zr, and 13 [[nuclear isomer]]s are also listed.{{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 | article-number=014614 | bibcode=2021PhRvC.103a4614S |s2cid = 234019083|display-authors = 1|hdl = 10261/260248|hdl-access = free}}</ref> The most stable among them is [[Zirconium-93|<sup>93</sup>Zr]], a [[long-lived fission product]], with a half-life of 1.61 million&nbsp;years. Radioactive isotopes at or above mass number 93 decay by [[beta decay|electron emission]] resulting in [[Isotopes of niobium|niobium]] isotopes, whereas those at or below 89 decay by [[beta decay|positron emission]] or [[electron capture]], resulting in [[Isotopes of yttrium|yttrium]] isotopes.{{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=https://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2014-zirco.pdf|access-date=2015-04-09|archive-date=2019-01-11|archive-url=https://web.archive.org/web/20190111161558/https://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= https://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2008-zirco.pdf |access-date= 2008-02-24 |archive-date= 2012-03-03 |archive-url= https://web.archive.org/web/20120303153111/http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2008-zirco.pdf }}</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|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|url-access=subscription }}</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>

==Production==

=== Occurrence ===
[[File:2005zirconium.PNG|thumb|Zirconium output in 2005]]
Zirconium is a by-product formed after mining and processing of the [[titanium]] minerals [[ilmenite]] and [[rutile]], as well as [[tin]] mining.<ref>{{cite web|last=Callaghan|first=R.|title=Zirconium and Hafnium Statistics and Information|publisher=US Geological Survey|date=2008-02-21|url=https://minerals.usgs.gov/minerals/pubs/commodity/zirconium/|access-date=2008-02-24|archive-date=2018-02-18|archive-url=https://web.archive.org/web/20180218030521/https://minerals.usgs.gov/minerals/pubs/commodity/zirconium/}}</ref> From 2003 to 2007, while prices for the mineral zircon steadily increased from $360 to $840 per tonne, the price for unwrought zirconium metal decreased from $39,900 to $22,700 per ton. Zirconium metal is much more expensive than [[zircon]] because the reduction processes are costly.<ref name="usgs2008" />

Collected from coastal waters, zircon-bearing sand is purified by [[spiral separator#Wet Spiral Separators|spiral concentrators]] to separate lighter materials, which are then returned to the water because they are natural components of beach sand. Using [[magnetic separation]], the titanium ores [[ilmenite]] and [[rutile]] are removed.<ref>{{Cite journal |last1=Siddiqui |first1=A. S. |last2=Mohapatra |first2=A. K. |last3=Rao |first3=J. V. |date=2000 |title=Separation of beach sand minerals |url=https://core.ac.uk/download/pdf/297712279.pdf |journal=Processing of Fines |location=India |volume=2 |pages=114–126 |isbn=81-87053-53-4}}</ref><!--Rutile is nonmagnetic, maybe has Fe impurities?-->

Most zircon is used directly in commercial applications, but a small percentage is converted to the metal. Most Zr metal is produced by the reduction of the [[zirconium(IV) chloride]] with [[magnesium]] metal in the [[Kroll process]].<ref name="CRC2008" /> The resulting metal is [[sintering|sintered]] until sufficiently ductile for metalworking.<ref name="madehow" />

===Separation of zirconium and hafnium===
Commercial zirconium metal typically contains 1–3% of [[hafnium]],<ref name="Ullmann" /> which is usually not problematic because the chemical properties of hafnium and zirconium are very similar. Their neutron-absorbing properties differ strongly, however, necessitating the separation of hafnium from zirconium for nuclear reactors.<ref name="Stwertka" /> Several separation schemes are in use.<ref name="Ullmann">Nielsen, Ralph (2005) "Zirconium and Zirconium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a28_543}}</ref> The [[liquid-liquid extraction]] of the [[thiocyanate]]-oxide derivatives exploits the fact that the hafnium derivative is slightly more soluble in [[methyl isobutyl ketone]] than in water. This method accounts for roughly two-thirds of pure zirconium production,<ref>{{Cite journal |last1=Wu |first1=Ming |last2=Xu |first2=Fei |last3=Dong |first3=Panfei |last4=Wu |first4=Hongzhen |last5=Zhao |first5=Zhiying |last6=Wu |first6=Chenjie |last7=Chi |first7=Ruan |last8=Xu |first8=Zhigao |date=January 2022 |title=Process for synergistic extraction of Hf(IV) over Zr(IV) from thiocyanic acid solution with TOPO and N1923 |url=https://linkinghub.elsevier.com/retrieve/pii/S0255270121003615 |journal=Chemical Engineering and Processing - Process Intensification |language=en |volume=170 |article-number=108673 |doi=10.1016/j.cep.2021.108673|bibcode=2022CEPPI.17008673W |url-access=subscription }}</ref> though other methods are being researched;<ref name=":0">{{Cite journal |last1=Xiong |first1=Jing |last2=Li |first2=Yang |last3=Zhang |first3=Xiaomeng |last4=Wang |first4=Yong |last5=Zhang |first5=Yanlin |last6=Qi |first6=Tao |date=2024-03-25 |title=The Extraction Mechanism of Zirconium and Hafnium in the MIBK-HSCN System |journal=Separations |language=en |volume=11 |issue=4 |page=93 |doi=10.3390/separations11040093 |issn=2297-8739 |doi-access=free}}</ref> for instance, in India, a TBP-nitrate solvent extraction process is used for the separation of zirconium from other metals.<ref>{{Cite journal |last1=Pandey |first1=Garima |last2=Darekar |first2=Mayur |last3=Singh |first3=K.K. |last4=Mukhopadhyay |first4=S. |date=2023-11-02 |title=Selective extraction of zirconium from zirconium nitrate solution in a pulsed stirred column |url=https://www.tandfonline.com/doi/full/10.1080/01496395.2023.2232102 |journal=Separation Science and Technology |language=en |volume=58 |issue=15–16 |pages=2710–2717 |doi=10.1080/01496395.2023.2232102 |issn=0149-6395|url-access=subscription }}</ref> Zr and Hf can also be separated by [[fractional crystallization (chemistry)|fractional crystallization]] of potassium hexafluorozirconate (K<sub>2</sub>ZrF<sub>6</sub>), which is less soluble in water than the analogous hafnium derivative. [[Fractional distillation]] of the tetrachlorides, also called [[extractive distillation]], is also used.<ref name=":0" /><ref>{{Cite book |last1=Xu |first1=L. |last2=Xiao |first2=Y. |last3=van Sandwijk |first3=A. |last4=Xu |first4=Q. |last5=Yang |first5=Y. |chapter=Separation of Zirconium and Hafnium: A Review |date=2016 |title=Energy Materials 2014 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-319-48765-6_53 |language=en |location=Cham |publisher=Springer International Publishing |pages=451–457 |doi=10.1007/978-3-319-48765-6_53 |isbn=978-3-319-48765-6}}</ref>

Vacuum [[Electric arc furnace|arc melting]], combined with the use of hot extruding techniques and [[Supercooling|supercooled]] copper hearths, is capable of producing zirconium that has been purified of oxygen, nitrogen, and carbon.<ref>{{Cite book |last=Shamsuddin |first=Mohammad |url=https://link.springer.com/book/10.1007/978-3-030-58069-8 |title=Physical Chemistry of Metallurgical Processes |series=The Minerals, Metals & Materials Series |date=22 June 2021 |publisher=Springer Cham |isbn=978-3-030-58069-8 |edition=2nd |pages=1-5, 390-391 |language=en |doi=10.1007/978-3-030-58069-8}}</ref>

Hafnium must be removed from zirconium for nuclear applications because hafnium has a neutron absorption cross-section 600 times greater than zirconium.<ref name="b1">{{cite book|author=Brady, George Stuart|author2=Clauser, Henry R.|author3=Vaccari, John A.|name-list-style=amp |title=Materials handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors|url=https://books.google.com/books?id=vIhvSQLhhMEC&pg=PA1063|access-date=2011-03-18 |year=2002|publisher=McGraw-Hill Professional|isbn=978-0-07-136076-0|pages=1063–}}</ref> The separated hafnium can be used for reactor [[control rods]].<ref>{{cite book|author=Zardiackas, Lyle D.|author2=Kraay, Matthew J.|author3=Freese, Howard L.|name-list-style=amp |title=Titanium, niobium, zirconium and tantalum for medical and surgical applications|url=https://books.google.com/books?id=iAlt_F5K9KkC&pg=PA21|access-date=2011-03-18 |year= 2006|publisher=ASTM International|isbn=978-0-8031-3497-3|pages=21–}}</ref>

==Compounds==
{{Category see also|Zirconium compounds|Zirconium minerals}}
Like other [[transition metal]]s, zirconium forms a wide range of [[inorganic chemistry|inorganic compounds]] and [[coordination complex]]es.<ref name="Greenwd">{{Greenwood&Earnshaw2nd}}</ref> In general, these compounds are colourless diamagnetic solids wherein zirconium has the [[oxidation state]] +4. Some organometallic compounds are considered to have Zr(II) oxidation state.<ref name="Calderazzo"/> Non-equilibrium oxidation states between 0 and 4 have been detected during zirconium oxidation.<ref name="Ma"/>

===Oxides, nitrides, and carbides===

{{Redirect|ZrO||ZRO (disambiguation){{!}}ZRO}}

The most common oxide is [[zirconium dioxide]], ZrO<sub>2</sub>, also known as ''zirconia''. This clear to white-coloured solid has exceptional [[fracture toughness]] (for a ceramic) and chemical resistance, especially in its [[cubic zirconia|cubic]] form.<ref name="azomzirc">{{cite web |title=Zirconia |publisher=AZoM.com |date=2008 |url=http://www.azom.com/details.asp?ArticleID=133#_Key_Properties |access-date=2008-03-17 |archive-date=2009-01-26 |archive-url=https://web.archive.org/web/20090126182009/http://www.azom.com/details.asp?ArticleID=133#_Key_Properties }}</ref> These properties make zirconia useful as a [[thermal barrier]] coating,<ref>{{cite journal|last1=Gauthier |first1=V. |last2=Dettenwanger|first2=F.|last3=Schütze|first3=M.|title=Oxidation behavior of γ-TiAl coated with zirconia thermal barriers |journal=Intermetallics |volume=10 |issue=7|pages=667–674|date=2002-04-10 |doi=10.1016/S0966-9795(02)00036-5}}</ref> although it is also a common [[diamond]] substitute.<ref name="azomzirc" /> Zirconium monoxide, ZrO, is also known and [[S-type star]]s are recognised by detection of its emission lines.<ref>{{cite journal|title= Classification of the S-Type Stars|last= Keenan|first= P. C.|year= 1954|journal= [[Astrophysical Journal]]|volume= 120|pages= 484–505|doi= 10.1086/145937|bibcode= 1954ApJ...120..484K}}</ref>

[[Zirconium tungstate]] has the unusual property of shrinking in all dimensions when heated, whereas most other substances expand when heated.<ref name="CRC2008" /> [[Zirconyl chloride]] is one of the few water-soluble zirconium complexes, with the formula [Zr<sub>4</sub>(OH)<sub>12</sub>(H<sub>2</sub>O)<sub>16</sub>]Cl<sub>8</sub>.<ref name="Greenwd"/>

[[Zirconium carbide]] and [[zirconium nitride]] are refractory solids. Both are highly [[corrosion]]-resistant and find uses in high-temperature resistant coatings and cutting tools.<ref>{{Cite journal |last1=Opeka |first1=Mark M. |last2=Talmy |first2=Inna G. |last3=Wuchina |first3=Eric J. |last4=Zaykoski |first4=James A. |last5=Causey |first5=Samuel J. |date=October 1999 |title=Mechanical, Thermal, and Oxidation Properties of Refractory Hafnium and zirconium Compounds |url=https://linkinghub.elsevier.com/retrieve/pii/S0955221999001296 |journal=Journal of the European Ceramic Society |language=en |volume=19 |issue=13–14 |pages=2405–2414 |doi=10.1016/S0955-2219(99)00129-6|url-access=subscription }}</ref> Zirconium hydride phases are known to form when zirconium alloys are exposed to large quantities of [[hydrogen]] over time; due to the brittleness of zirconium hydrides relative to zirconium alloys, the mitigation of zirconium hydride formation was highly studied during the development of the first commercial [[Nuclear reactor|nuclear reactors]], in which zirconium carbide was a frequently used material.<ref>{{Cite book |last=Puls |first=Manfred P. |url=https://link.springer.com/book/10.1007/978-1-4471-4195-2 |title=The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components |series=Engineering Materials |date=2012 |publisher=Springer London |language=en |doi=10.1007/978-1-4471-4195-2|isbn=978-1-4471-4194-5 }}</ref>

[[Lead zirconate titanate]] (PZT) is the most commonly used [[Piezoelectricity|piezoelectric]] material, being used as [[Transducer|transducers]] and [[Actuator|actuators]] in medical and [[MEMS|microelectromechanical systems]] applications.<ref>{{Cite journal |last1=Rouquette |first1=J. |last2=Haines |first2=J. |last3=Bornand |first3=V. |last4=Pintard |first4=M. |last5=Papet |first5=Ph. |last6=Bousquet |first6=C. |last7=Konczewicz |first7=L. |last8=Gorelli |first8=F. A. |last9=Hull |first9=S. |date=2004-07-23 |title=Pressure tuning of the morphotropic phase boundary in piezoelectric lead zirconate titanate |url=https://link.aps.org/doi/10.1103/PhysRevB.70.014108 |journal=Physical Review B |language=en |volume=70 |issue=1 |article-number=014108 |doi=10.1103/PhysRevB.70.014108 |bibcode=2004PhRvB..70a4108R |issn=1098-0121|url-access=subscription }}</ref>

===Halides and pseudohalides===
All four common halides are known, [[zirconium(IV) fluoride|ZrF<sub>4</sub>]], [[zirconium(IV) chloride|ZrCl<sub>4</sub>]], [[zirconium(IV) bromide|ZrBr<sub>4</sub>]], and [[zirconium(IV) iodide|ZrI<sub>4</sub>]]. All have polymeric structures and are far less volatile than the corresponding titanium tetrahalides; they find applications in the formation of organic complexes such as [[zirconocene dichloride]].<ref name=":1">{{Cite journal |last1=South Ural State University, Chelyabinsk, Russian Federation |last2=Sharutin |first2=V. |last3=Tarasova |first3=N. |date=2023 |title=Zirconium halide complexes. Synthesis, structure, practical application potential |url=https://vestnik.susu.ru/chemistry/article/view/12998 |journal=Bulletin of the South Ural State University Series "Chemistry" |language=ru |volume=15 |issue=1 |pages=17–30 |doi=10.14529/chem230102|doi-access=free }}</ref> All tend to [[hydrolyse]] to give the so-called oxyhalides and dioxides.<ref name="Ullmann" />

Fusion of the tetrahalides with additional metal gives lower zirconium halides (e.g. [[Zirconium(III) chloride|ZrCl<sub>3</sub>]]).  These adopt a layered structure, conducting within the layers but not perpendicular thereto.<ref>{{ cite book | title = Inorganic Chemistry | last1 = Housecroft | first1 = C. E. | last2 = Sharpe | first2 = A. G. | year = 2018 | publisher = [[Prentice-Hall]] | edition = 5th | isbn = 978-0-273-74275-3 | page = 812 }}</ref>  

The corresponding tetra[[alkoxide]]s are also known. Unlike the halides, the alkoxides dissolve in nonpolar solvents. Dihydrogen hexafluorozirconate is used in the metal finishing industry as an etching agent to promote paint adhesion.<ref>MSDS sheet for Duratec 400, DuBois Chemicals, Inc.</ref>

===Organic derivatives===
{{main|Organozirconium chemistry}}

[[File:Zirconocene-dichloride-from-xtal-3D-balls.png|right|upright=0.85|thumb|[[Zirconocene dichloride]], a representative [[organozirconium compound]]]]
[[Organozirconium chemistry]] is key to [[Ziegler–Natta catalyst]]s, used to produce [[polypropylene]]. This application exploits the ability of zirconium to reversibly form bonds to carbon. Zirconocene dibromide ((C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>ZrBr<sub>2</sub>), reported in 1952 by Birmingham and [[Geoffrey Wilkinson|Wilkinson]], was the first organozirconium compound.<ref>{{cite journal |author= Wilkinson, G. |date= 1954 |title= Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta |journal= Journal of the American Chemical Society|volume= 76 |issue= 17 |pages= 4281–4284 |doi= 10.1021/ja01646a008 |author-link= Geoffrey Wilkinson |last2= Birmingham |first2= J. M.|bibcode= 1954JAChS..76.4281W }}; {{cite journal |last=Rouhi|first=A. Maureen|title=Organozirconium Chemistry Arrives|journal= Chemical & Engineering News|volume=82|issue=16|pages=36–39|date=2004-04-19|url=http://pubs.acs.org/cen/nlw/8216sci1.html|issn=0009-2347 |access-date=2008-03-17|doi=10.1021/cen-v082n016.p036|url-access=subscription}}</ref> [[Schwartz's reagent]], prepared in 1970 by P. C. Wailes and H. Weigold,<ref>{{cite journal|author=Wailes, P. C.|author2=Weigold, H.|name-list-style=amp|title=Hydrido complexes of zirconium I. Preparation|journal=[[Journal of Organometallic Chemistry]]|date=1970|volume=24|pages=405–411|doi=10.1016/S0022-328X(00)80281-8|issue=2}}</ref> is a [[metallocene]] used in [[organic synthesis]] for transformations of [[alkenes]] and [[alkyne]]s.<ref name="hart">{{cite journal|author=Hart, D. W.|author2=Schwartz, J.|name-list-style=amp |title=Hydrozirconation. Organic Synthesis via Organozirconium Intermediates. Synthesis and Rearrangement of Alkylzirconium(IV) Complexes and Their Reaction with Electrophiles |journal= Journal of the American Chemical Society|volume=96 |issue=26|date=1974|pages=8115–8116|doi=10.1021/ja00833a048|bibcode=1974JAChS..96.8115H }}</ref>

Many complexes of Zr(II) are derivatives of zirconocene,<ref name=":1" /> one example being (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>Zr(CO)<sub>2</sub>.

==History==
The zirconium-containing mineral zircon and related minerals ([[jargoon]], [[jacinth]], or hyacinth, [[Priestly breastplate#Third row|ligure]]) were mentioned in biblical writings.<ref name="CRC2008" /><ref name="Stwertka" /> The mineral was not known to contain a new element until 1789,<ref name="greenwood">{{cite book|title=The History and Use of our Earth's Chemical Elements|last=Krebs|first=Robert E.|date=1998|publisher=Greenwood Press|isbn=978-0-313-30123-0|location=Westport, Connecticut|pages=[https://archive.org/details/historyuseofoure00kreb/page/98 98–100]|url-access=registration|url=https://archive.org/details/historyuseofoure00kreb/page/98}}</ref> when [[Martin Heinrich Klaproth|Klaproth]] analyzed a jargoon from the island of Ceylon (now [[Sri Lanka]]). He named the new element Zirkonerde (zirconia),<ref name="CRC2008" /> related to the [[Persian Language|Persian]] ''[[Jargoon|zargun]]'' (zircon; ''zar-gun'', "gold-like" or "as gold").<ref name=":2" /> [[Humphry Davy]] attempted to isolate this new element in 1808 through [[electrolysis]], but failed.<ref name="nbb" /> Zirconium metal was first obtained in an impure form in 1824 by [[Jöns Jakob Berzelius|Berzelius]] by heating a mixture of potassium and potassium zirconium fluoride in an iron tube.<ref name="CRC2008" /> 

The ''[[crystal bar process]]'' (also known as the ''Iodide Process''), discovered by [[Anton Eduard van Arkel]] and [[Jan Hendrik de Boer]] in 1925, was the first industrial process for the commercial production of metallic zirconium. It involves the formation and subsequent [[thermal decomposition]] of [[zirconium tetraiodide]] ({{chem2|ZrI4}}), and was superseded in 1945 by the much cheaper [[Kroll process]] developed by [[William Justin Kroll]], in which zirconium tetrachloride ({{chem2|ZrCl4}}) is reduced by magnesium:<ref name="madehow" /><ref name="metal1998">{{cite book|first=James B.|last=Hedrick|contribution=Zirconium|title=Metal Prices in the United States through 1998|date=1998|pages=175–178|publisher=US Geological Survey|url=https://minerals.usgs.gov/minerals/pubs/metal_prices/metal_prices1998.pdf|access-date=2008-02-26|archive-date=2024-03-24|archive-url=https://web.archive.org/web/20240324162757/http://minerals.usgs.gov/minerals/pubs/metal_prices/metal_prices1998.pdf}}</ref>

:{{chem2 | ZrCl4 + 2 Mg -> Zr + 2 MgCl2 }}

==Applications==
Approximately 900,000 tonnes of zirconium ores were mined in 1995, mostly as zircon.<ref name="Ullmann" />

Most zircon is used directly in high-temperature applications. Because it is refractory, hard, and resistant to chemical attack, zircon finds many applications. Its main use is as an opacifier, conferring a white, opaque appearance to ceramic materials. Because of its chemical resistance, zircon is also used in aggressive environments, such as moulds for molten metals.<ref name="Ullmann" />

[[Zirconium dioxide]] (ZrO<sub>2</sub>) is used in laboratory crucibles, in metallurgical furnaces, and as a refractory material<ref name="CRC2008" /> Because it is mechanically strong and flexible, it can be [[sintered]] into [[ceramic knife|ceramic knives]] and other blades.<ref name="kyo">{{cite web |title= Fine ceramics – zirconia |publisher= Kyocera Inc. |url=http://global.kyocera.com/prdct/fc/list/material/zirconia/zirconia.html}}</ref> Zircon (ZrSiO<sub>4</sub>) and [[cubic zirconia]] (ZrO<sub>2</sub>) are cut into gemstones for use in jewelry. Zirconium dioxide is a component in some [[abrasive]]s, such as grinding wheels and [[sandpaper]].<ref name="greenwood" /> Zircon is also used in [[Detrital zircon geochronology|dating of rocks]] from about the time of the Earth's formation through the measurement of its inherent [[Radionuclide|radioisotopes]], most often [[uranium]] and [[lead]].<ref>{{multiref2|{{cite journal|last1=Davis|first1=Donald W.|last2=Williams|first2=Ian S.|last3=Krogh|first3=Thomas E.|year=2003|title=Historical development of U-Pb geochronology|editor=Hanchar, J.M. |editor2=Hoskin, P.W.O.|journal=Zircon: Reviews in Mineralogy and Geochemistry|volume=53|pages=145–181|url=http://people.uncw.edu/lamaskint/GLY%20445-545%20FALL%202013/Davis%20et%20al%20Historical%20Development%20of%20Zircon%20Geochronology.pdf|doi=10.2113/0530145}}|{{cite journal|author1=Kosler, J.|author2=Sylvester, P.J.|year=2003|title=Present trends and the future of zircon in U-Pb geochronology: laser ablation ICPMS|editor=Hanchar, J.M. |editor2=Hoskin, P.W.O.|journal=Zircon: Reviews in Mineralogy and Geochemistry|volume=53|issue=1|pages=243–275|doi=10.2113/0530243|bibcode=2003RvMG...53..243K}}|{{cite journal|author1=Fedo, C. M.|author2=Sircombe, K. N.|author3=Rainbird, R. H.|year=2003|title=Detrital zircon analysis of the sedimentary record|journal=Reviews in Mineralogy and Geochemistry|volume=53|issue=1|pages=277–303|doi=10.2113/0530277|bibcode=2003RvMG...53..277F}}}}</ref>

{{Further information|Zirconium alloys}}

A small fraction of the zircon is converted to the metal, which finds various niche applications. Because of zirconium's excellent resistance to corrosion, it is often used as an alloying agent in materials that are exposed to aggressive environments, such as surgical appliances, light filaments, and watch cases. The high reactivity of zirconium with oxygen at high temperatures is exploited in some specialised applications such as explosive primers and as [[getter]]s in [[vacuum tube]]s.<ref>{{cite journal |last=Rogers |first=Alfred |year=1946 |title=Use of Zirconium in the Vacuum Tube |journal=Transactions of the Electrochemical Society |volume=88 |page=207 |doi=10.1149/1.3071684}}</ref> Zirconium powder is used as a degassing agent in electron tubes, while zirconium wire and sheets are utilized for grid and [[anode]] supports.<ref>{{cite web |url=https://www.refractorymetal.org/the-magic-industrial-vitamin-zirconium-metal/ |title=Zirconium Metal: The Magic Industrial Vitamin |website=Advanced Refractory Metals |access-date=Oct 21, 2024}}</ref><ref>{{cite journal |last=Ferrando |first=W.A. |year=1988 |title=Processing and use of zirconium based materials |journal=Advanced Materials and Manufacturing Processes |volume=3 |issue=2 |pages=195–231 |doi=10.1080/10426918808953203}}</ref> Burning zirconium was used as a light source in some [[flash (photography)#Flashbulbs|photographic flashbulbs]]. Zirconium powder with a [[Mesh (scale)|mesh size]] from 10 to 80 is occasionally used in pyrotechnic compositions to generate [[Spark (fire)|sparks]]. The high reactivity of zirconium leads to bright white sparks.<ref name="stars">{{citation |url=https://books.google.com/books?id=e4GOAIA8HaEC&pg=PA49 |title=Pyrotechnic Spark Generation |author1=Kosanke, Kenneth L. |author2=Kosanke, Bonnie J. |pages=49–62 |journal=Journal of Pyrotechnics |isbn=978-1-889526-12-6 |year=1999 }}</ref>

=== Nuclear applications ===

Cladding for nuclear reactor fuels consumes about 1% of the zirconium supply,<ref name="Ullmann" /> mainly in the form of [[zircaloy]]s. The desired properties of these alloys are a low neutron-capture [[neutron cross-section|cross-section]] and resistance to corrosion under normal service conditions.<ref name="madehow">{{cite web |title= Zirconium |work= How Products Are Made |publisher= Advameg Inc. |date= 2007 |url=http://www.madehow.com/Volume-1/Zirconium.html |access-date= 2008-03-26}}</ref><ref name="CRC2008" /> Efficient methods for removing the hafnium impurities were developed to serve this purpose.<ref name="Stwertka" />

One disadvantage of zirconium alloys is the reactivity with water, producing [[hydrogen]], leading to degradation of the [[nuclear fuel#Common physical forms of nuclear fuel|fuel rod cladding]]:<ref>{{Cite journal |last1=Motta |first1=Arthur T. |last2=Capolungo |first2=Laurent |last3=Chen |first3=Long-Qing |last4=Cinbiz |first4=Mahmut Nedim |last5=Daymond |first5=Mark R. |last6=Koss |first6=Donald A. |last7=Lacroix |first7=Evrard |last8=Pastore |first8=Giovanni |last9=Simon |first9=Pierre-Clément A. |last10=Tonks |first10=Michael R. |last11=Wirth |first11=Brian D.|author11-link=Brian Wirth |last12=Zikry |first12=Mohammed A. |date=May 2019 |title=Hydrogen in zirconium alloys: A review |url=https://linkinghub.elsevier.com/retrieve/pii/S0022311518316763 |journal=Journal of Nuclear Materials |language=en |volume=518 |pages=440–460 |doi=10.1016/j.jnucmat.2019.02.042|bibcode=2019JNuM..518..440M }}</ref>

:{{chem2 | Zr + 2 H2O -> ZrO2 + 2 H2 }}

Hydrolysis is very slow below 100&nbsp;°C, but rapid at temperature above 900&nbsp;°C. Most metals undergo similar reactions. The redox reaction is relevant to the instability of [[nuclear fuel|fuel assemblies]] at high temperatures.<ref>Gillon, Luc (1979). ''Le nucléaire en question'', Gembloux Duculot, French edition.</ref> This reaction occurred in the reactors 1, 2 and 3 of the [[Fukushima I Nuclear Power Plant]] (Japan) after the reactor cooling was interrupted by the [[2011 Tōhoku earthquake and tsunami|earthquake and tsunami]] disaster of March 11, 2011, leading to the [[Fukushima I nuclear accidents]]. After venting the hydrogen in the maintenance hall of those three reactors, the mixture of hydrogen with atmospheric [[oxygen]] exploded, severely damaging the installations and at least one of the containment buildings.<ref name="IAEA2015">{{cite book |url=https://www.iaea.org/publications/10962/the-fukushima-daiichi-accident |title=The Fukushima Daiichi accident |date=2015 |publisher=International Atomic Energy Agency |isbn=978-92-0-107015-9 |series=STI/PUB |location=Vienna, Austria |pages=37–42}}</ref>

Zirconium is a constituent of [[uranium zirconium hydride]]s, nuclear fuels used in [[research reactor]]s.<ref>{{multiref2|{{Cite journal |last1=Tsuchiya |first1=B. |last2=Huang |first2=J. |last3=Konashi |first3=K. |last4=Teshigawara |first4=M. |last5=Yamawaki |first5=M. |date=March 2001 |title=Thermophysical properties of zirconium hydride and uranium–zirconium hydride |url=https://linkinghub.elsevier.com/retrieve/pii/S0022311501004202 |journal=Journal of Nuclear Materials |language=en |volume=289 |issue=3 |pages=329–333 |doi=10.1016/S0022-3115(01)00420-2|bibcode=2001JNuM..289..329T |url-access=subscription }}|{{Cite journal |last1=Olander |first1=D. |last2=Greenspan |first2=Ehud |last3=Garkisch |first3=Hans D. |last4=Petrovic |first4=Bojan |date=August 2009 |title=Uranium–zirconium hydride fuel properties |url=https://linkinghub.elsevier.com/retrieve/pii/S0029549309001745 |journal=Nuclear Engineering and Design |language=en |volume=239 |issue=8 |pages=1406–1424 |doi=10.1016/j.nucengdes.2009.04.001|bibcode=2009NuEnD.239.1406O |url-access=subscription }}}}</ref>

=== Space and aeronautic industries ===

Materials fabricated from zirconium metal and ZrO<sub>2</sub> are used in space vehicles where resistance to heat is needed.<ref name="Stwertka">{{cite book|last=Stwertka|first=Albert|title=A Guide to the Elements|publisher=Oxford University Press|date=1996|pages=117–119 |isbn= 978-0-19-508083-4}}</ref>

High temperature parts such as combustors, blades, and vanes in [[jet engine]]s and stationary [[gas turbine]]s are increasingly being protected by thin [[ceramic]] layers and/or paintable coatings, usually composed of a mixture of zirconia and [[yttria]].<ref>{{multiref2|{{cite journal|doi= 10.1115/1.2906801|title= The Evolution of Thermal Barrier Coatings in Gas Turbine Engine Applications|date= 1994|last1= Meier|first1= S. M.|last2= Gupta|first2= D. K.|journal= Journal of Engineering for Gas Turbines and Power|volume= 116|pages= 250–257|s2cid= 53414132}}|{{Cite journal |last=Allison |first=S. W. |title=37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit |url=https://technicalreports.ornl.gov/cppr/y2001/pres/112377.pdf |journal=AIAA/ASME/SAE/ASEE Joint Propulsion Conference |archive-date=2023-08-27 |access-date=2023-08-27 |archive-url=https://web.archive.org/web/20230827185802/https://technicalreports.ornl.gov/cppr/y2001/pres/112377.pdf }}}}</ref>

Zirconium is also used as a material of first choice for [[hydrogen peroxide]] ({{chem2|H2O2}}) tanks, propellant lines, valves, and thrusters, in [[Spacecraft propulsion|propulsion space systems]] such as these equipping the [[Sierra Space]]'s [[Dream Chaser]] [[spaceplane]]<ref name="Clark2023" /> where the [[thrust]] is provided by the [[combustion]] of [[kerosene]] and hydrogen peroxide, a powerful, but unstable, [[oxidizer]]. The reason is that zirconium has an excellent [[Corrosion#Resistance to corrosion|corrosion resistance]] to {{chem2|H2O2}} and, above all, do not [[catalysis|catalyse]] its spontaneous self-decomposition as the [[ion]]s of many [[transition metal]]s do.<ref name="Clark2023">{{cite web | last=Clark | first=Stephen | title=After decades of dreams, a commercial spaceplane is almost ready to fly | website=Ars Technica | date=2023-11-01 | url=https://arstechnica.com/space/2023/11/after-decades-of-dreams-a-commercial-spaceplane-is-almost-ready-to-fly/ | access-date=2023-11-03}}</ref><ref name="Zircadyne">{{cite web | author= ATI Materials | title=Zircadyne® 702/705 in Hydrogen Peroxide | url=https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zircadyne_702_705_in_hydrogen_peroxide_v1.pdf | work= atimaterials | access-date=2023-11-03}}</ref>

=== Medical uses ===

Zirconium-bearing compounds are used in many biomedical applications, including dental implants and [[crown (dentistry)|crowns]], knee and hip replacements, middle-ear [[ossicles|ossicular]] chain reconstruction, and other restorative and [[prosthesis|prosthetic]] devices.<ref name="Lee" />

Zirconium binds [[urea]], a property that has been utilized extensively to the benefit of patients with [[chronic kidney disease]].<ref name="Lee" /> For example, zirconium is a primary component of the [[sorbent]] column dependent dialysate regeneration and recirculation system known as the REDY system, which was first introduced in 1973. More than 2,000,000 [[Kidney dialysis|dialysis]] treatments have been performed using the sorbent column in the REDY system.<ref>Ash SR. Sorbents in treatment of uremia: A short history and a great future. 2009 Semin Dial 22: 615–622</ref> Although the REDY system was superseded in the 1990s by less expensive alternatives, new sorbent-based dialysis systems are being evaluated and approved by the U.S. [[Food and Drug Administration]] (FDA). Renal Solutions developed the DIALISORB technology, a portable, low water dialysis system. Also, developmental versions of a Wearable Artificial Kidney have incorporated sorbent-based technologies.<ref>{{Cite journal |last=Kooman |first=Jeroen Peter |date=2024-03-20 |title=The Revival of Sorbents in Chronic Dialysis Treatment |journal=Seminars in Dialysis |volume=38 |issue=1 |pages=54–61 |language=en |doi=10.1111/sdi.13203 |issn=0894-0959|doi-access=free |pmid=38506130 |pmc=11867157 }}</ref>

[[Sodium zirconium cyclosilicate]] is used by mouth in the treatment of [[hyperkalemia]]. It is a selective sorbent designed to trap [[potassium]] ions in preference to other [[ions]] throughout the gastrointestinal tract.<ref>{{cite journal |doi= 10.1056/NEJMe1414112 |pmid= 25415806 |title= A New Era for the Treatment of Hyperkalemia? |journal= New England Journal of Medicine |volume= 372 |issue= 3 |pages= 275–7 |year= 2015 |last1= Ingelfinger |first1= Julie R.}}</ref>

Mixtures of monomeric and polymeric Zr<sup>4+</sup> and Al<sup>3+</sup> complexes with [[hydroxide]], [[chloride]] and [[glycine]], called [[Aluminium zirconium tetrachlorohydrex gly|aluminium zirconium glycine]] salts, are used in a preparation as an [[antiperspirant]] in many [[deodorant]] products. It has been used since the early 1960s, as it was determined more efficacious as an antiperspirant than contemporary active ingredients such as [[aluminium chlorohydrate]].<ref>{{Cite book |last=Laden |first=Karl |url=https://books.google.com/books?id=n0FZDwAAQBAJ |title=Antiperspirants and Deodorants |date=January 4, 1999 |publisher=CRC Press |isbn=978-1-4822-2405-4 |pages=137–144 |language=en}}</ref>

=== Defunct applications ===

Zirconium carbonate (3ZrO<sub>2</sub>·CO<sub>2</sub>·H<sub>2</sub>O) was used in lotions to treat [[poison ivy]] but was discontinued because it occasionally caused skin reactions.<ref name="nbb">{{cite book |last= Emsley |first= John |title= Nature's Building Blocks |publisher= Oxford University Press |date= 2001 |location= Oxford |pages= 506–510 |isbn= 978-0-19-850341-5}}</ref>

==Safety==
{{Chembox
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|Section7={{Chembox Hazards
| ExternalSDS =
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Although zirconium has no known biological role, the human body contains, on average, 250 milligrams of zirconium, and daily intake is approximately 4.15 milligrams (3.5 milligrams from food and 0.65 milligrams from water), depending on dietary habits.<ref name = Schroeder-and-Balassa-1966>
{{cite journal
 | author-last    = Schroeder
 | author-first   = Henry A.
 | author-last2   = Balassa
 | author-first2  = Joseph J.
 | date           = May 1966
 | title          = Abnormal trace metals in man: zirconium
 | journal        = Journal of Chronic Diseases
 | volume         = 19
 | issue          = 5
 | pages          = 573–586
 | doi            = 10.1016/0021-9681(66)90095-6
 | pmid           = 5338082
}}</ref> Zirconium is widely distributed in nature and is found in all biological systems, for example: 2.86 μg/g in whole wheat, 3.09 μg/g in brown rice, 0.55 μg/g in [[spinach]], 1.23 μg/g in eggs, and 0.86 μg/g in ground beef.{{r|Schroeder-and-Balassa-1966}} Further, zirconium is commonly used in commercial products (e.g. [[deodorant]] sticks, aerosol [[antiperspirants]]) and also in water purification (e.g. control of [[phosphorus]] pollution, bacteria- and pyrogen-contaminated water).<ref name="Lee">Lee DBN, Roberts M, Bluchel CG, Odell RA. (2010) Zirconium: Biomedical and nephrological applications. ASAIO J 56(6):550–556.</ref>

Short-term exposure to zirconium powder can cause irritation, but only contact with the eyes requires medical attention.<ref>{{cite book|contribution=Zirconium|title=International Chemical Safety Cards|date=October 2004|publisher=International Labour Organization|url=http://www.oit.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc14/icsc1405.htm|access-date=2008-03-30|archive-date=2008-12-01|archive-url=https://web.archive.org/web/20081201143952/http://www.oit.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc14/icsc1405.htm}}</ref> Persistent exposure to [[zirconium tetrachloride]] results in increased mortality in rats and guinea pigs and a decrease of blood [[hemoglobin]] and [[red blood cell]]s in dogs. However, in a study of 20 rats given a standard diet containing ~4% zirconium oxide, there were no adverse effects on growth rate, blood and urine parameters, or mortality.<ref>Zirconium and its compounds 1999. The MAK Collection for Occupational Health and Safety. 224–236</ref> The U.S. [[Occupational Safety and Health Administration]] (OSHA) legal limit ([[permissible exposure limit]]) for zirconium exposure is 5&nbsp;mg/m<sup>3</sup> over an 8-hour workday. The [[National Institute for Occupational Safety and Health]] (NIOSH) [[recommended exposure limit]] (REL) is 5&nbsp;mg/m<sup>3</sup> over an 8-hour workday and a short term limit of 10&nbsp;mg/m<sup>3</sup>. At levels of 25&nbsp;mg/m<sup>3</sup>, zirconium is [[IDLH|immediately dangerous to life and health]].<ref>{{cite web|title=NIOSH Pocket Guide to Chemical Hazards – Zirconium compounds (as Zr)|url=https://www.cdc.gov/niosh/npg/npgd0677.html|website=CDC|access-date= 2015-11-27}}</ref> However, zirconium is not considered an industrial health hazard.<ref name="Lee" /> Furthermore, reports of zirconium-related adverse reactions are rare and, in general, rigorous cause-and-effect relationships have not been established.<ref name="Lee" /> No evidence has been validated that zirconium is carcinogenic<ref>{{Cite web |last=PubChem |title=Zirconium, Elemental |url=https://pubchem.ncbi.nlm.nih.gov/source/hsdb/2528 |access-date=2024-10-25 |website=Hazardous Substances Data Bank |language=en}}</ref> or genotoxic.<ref>{{Cite book |url=https://onlinelibrary.wiley.com/doi/book/10.1002/3527600418 |title=The MAK-Collection for Occupational Health and Safety: Annual Thresholds and Classifications for the Workplace |chapter=Zirconium and its compounds &#91;MAK Value Documentation, 1999&#93; |date=November 2002 |pages=224–236 |publisher=Wiley |isbn=978-3-527-60041-0 |editor-last=Deutsche Forschungsgemeinschaft |edition=1 |language=de |doi=10.1002/3527600418.mb744067vere0012 |editor-last2=Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area}}</ref>

Among the numerous radioactive isotopes of zirconium, <sup>93</sup>Zr is among the most common. It is released as a [[Fission products (by element)#Zirconium-90 to 96|product of nuclear fission]] of <sup>235</sup>U and <sup>239</sup>Pu, mainly in nuclear power plants and during nuclear weapons tests in the 1950s and 1960s. It has a very long half-life (1.53 million years), its decay emits only low energy radiations, and it is not considered particularly hazardous.<ref>{{cite web |title=ANL Human Health Fact Sheet: Zirconium (October 2001) |url=http://hpschapters.org/northcarolina/NSDS/zirconium.pdf |publisher=Argonne National Laboratory |access-date=15 July 2020}}</ref>

==See also==
{{Portal|Chemistry}}
* [[Zirconium alloy]]s
* [[Zirconia light]]

==Notes==
{{Notelist}}

==References==
{{Reflist|30em}}

==External links==
{{Sister project links |wikt= |commons=Zirconium |b=no |n=no |q=no |s=no |v=no |species=no}}
* [http://www.rsc.org/chemistryworld/podcast/element.asp Chemistry in its element podcast] (MP3) from the [[Royal Society of Chemistry]]'s [[Chemistry World]]: [http://www.rsc.org/images/CIIE_zirconium_remix2_48k_tcm18-117340.mp3 Zirconium]
* [http://www.periodicvideos.com/videos/040.htm Zirconium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)

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