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			{{Redirect|Zirconia|the related silicate mineral|Zircon}}
	{{chembox
			{{Chembox
	| Watchedfields = changed		| Watchedfields = changed
	| verifiedrevid = 409733193		| verifiedrevid = 454439551
	| Name = Zirconium dioxide		| Name = Zirconium dioxide
	| ImageFile = ZrO2powder.jpg		| ImageFile1 = ZrO2powder.jpg
	| IUPACName = Zirconium dioxide<br/>Zirconium(IV) oxide		| ImageFile2 = Kristallstruktur Zirconium(IV)-oxid.png
			| IUPACName = Zirconium dioxide<br />Zirconium(IV) oxide
	| OtherNames = Zirconia<br/>]
			| OtherNames = Zirconia<br />]
	| Name = Zirconium dioxide
	| Section1 = {{Chembox Identifiers		|Section1={{Chembox Identifiers
			| CASNo_Ref = {{cascite|correct|CAS}}
	| CASNo = 1314-23-4		| CASNo = 1314-23-4
			| ChemSpiderID = 56183
	| CASNo_Ref = {{cascite}}
			| UNII_Ref = {{fdacite|correct|FDA}}
	}}
			| UNII = S38N85C5G0
	| Section2 = {{Chembox Properties
			| PubChem = 62395
			| EC_number = 215-227-2
			| StdInChI=1S/2O.Zr
			| StdInChIKey = MCMNRKCIXSYSNV-UHFFFAOYSA-N
			| SMILES = O==O
			}}
			|Section2={{Chembox Properties
	| Formula = {{chem|ZrO|2}}		| Formula = {{chem|ZrO|2}}
	| MolarMass = 123.218 g/mol		| MolarMass = 123.218 g/mol
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	| Density = 5.68 g/cm<sup>3</sup>		| Density = 5.68 g/cm<sup>3</sup>
	| Solubility = negligible		| Solubility = negligible
	| SolubleOther = soluble in ], and hot ], ], ]		| SolubleOther = soluble in ], and hot ]
	| MeltingPt = 2715 °C		| MeltingPtC = 2715
			| MeltingPt_notes =
	| BoilingPt = 4300 °C
			| BoilingPtC = 4300
			| BoilingPt_notes =
	| RefractIndex = 2.13		| RefractIndex = 2.13
	}}		}}
	| Section4 = {{Chembox Thermochemistry		|Section4={{Chembox Thermochemistry
	| DeltaHf = –1080 kJ/mol		| DeltaHf = –1080 kJ/mol
	| Entropy = 50.3 J&thinsp;K<sup>–1</sup>&thinsp;mol<sup>–1</sup>		| Entropy = 50.3 J{{thin space}}K<sup>−1</sup>{{thin space}}mol<sup>−1</sup>
	}}		}}
	| Section7 = {{Chembox Hazards		|Section7={{Chembox Hazards
	| ExternalMSDS =		| ExternalSDS =
	| EUIndex = Not listed
	| FlashPt = Non-flammable		| FlashPt = Non-flammable
	| LD50 = > 8.8 g/kg (oral, rat)		| LD50 = > 8.8 g/kg (oral, rat)
			| GHSPictograms = {{GHS exclamation mark}}
	}}
			| GHSSignalWord = Warning
	| Section8 = {{Chembox Related
			| HPhrases = {{H-phrases|315|319|335}}
			| PPhrases = {{P-phrases|261|264|271|280|302+352|304+340|305+351+338|312|321|332+313|337+313|362|403+233|405|501}}
			}}
			|Section8={{Chembox Related
	| OtherAnions = ]		| OtherAnions = ]
	| OtherCations = ]<br/>]		| OtherCations = ]<br />]
	}}		}}
	}}		}}
	'''Zirconium dioxide''' ({{chem|ZrO|2}}), sometimes known as '''zirconia''' (not to be confused with ]), is a white crystalline ] of ]. Its most naturally occurring form, with a ] crystalline structure, is the rare ] ]. The high temperature ] crystalline form is rarely found in nature as mineral tazheranite (Zr,Ti,Ca)O<sub>2</sub> (and a doubtful mineral arkelite). This form, also called ], is synthesized in various colours for use as a ] and a ].
			'''Zirconium dioxide''' ('''{{chem|ZrO|2}}'''), sometimes known as '''zirconia''' (not to be confused with zirconium silicate or ]), is a white crystalline ] of ]. Its most naturally occurring form, with a ], is the ] ]. A dopant{{clarify|date=May 2024}} stabilized cubic structured zirconia, ], is synthesized in various colours for use as a ] and a ].<ref>{{cite journal |last1=Wang |first1=S. F. |last2=Zhang |first2=J. |last3=Luo |first3=D. W. |last4=Gu |first4=F. |last5=Tang |first5=D. Y. |last6=Dong |first6=Z. L. |last7=Tan |first7=G. E. B. |last8=Que |first8=W. X. |last9=Zhang |first9=T. S. |last10=Li |first10=S. |last11=Kong |first11=L. B. |date=2013-05-01 |title=Transparent ceramics: Processing, materials and applications |journal=Progress in Solid State Chemistry |language=en |volume=41 |issue=1 |pages=20–54 |doi=10.1016/j.progsolidstchem.2012.12.002 |issn=0079-6786}}</ref>
	==Engineering properties==
	Zirconium dioxide is one of the most studied ] materials. Pure ZrO<sub>2</sub> has a ] ] at room temperature and transitions to ] and ] at increasing temperatures. The volume expansion caused by the cubic to tetragonal to monoclinic transformation induces very large stresses, and will cause pure ZrO<sub>2</sub> to crack upon cooling from high temperatures. Several different oxides are added to zirconia to stabilize the tetragonal and/or cubic phases: ] (MgO), ], (Y<sub>2</sub>O<sub>3</sub>), ] (CaO), and ] (Ce<sub>2</sub>O<sub>3</sub>), amongst others.<ref name=evans>{{cite journal|author=Evans, A.G., Cannon, R.M.|title=Toughening of brittle solids by martensitic transformations|journal=Acta Met.|volume=34|page=761|year=1986|doi=10.1016/0001-6160(86)90052-0}}</ref>
			==Production, chemical properties, occurrence==
	Zirconia is very useful in its 'stabilized' state. In some cases, the tetragonal phase can be ]. If sufficient quantities of the metastable tetragonal phase is present, then an applied stress, magnified by the ] at a crack tip, can cause the tetragonal phase to convert to monoclinic, with the associated volume expansion. This phase transformation can then put the crack into compression, retarding its growth, and enhancing the ]. This mechanism is known as ], and significantly extends the reliability and lifetime of products made with stabilized zirconia.
			Zirconia is produced by ] zirconium compounds, exploiting its high ].<ref name="Ullmann">Ralph Nielsen "Zirconium and Zirconium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a28_543}}</ref>
	<ref name=evans/><ref>{{cite journal|author=Porter, D.L., Evans, A.G., Heuer, A.H.|title=Transformation toughening in PSZ|journal=Acta Met.|volume=27|page=1649|year=1979|doi=10.1016/0001-6160(79)90046-4}}</ref>
			===Structure===
	The ZrO<sub>2</sub> ] is dependent on the phase (cubic, tetragonal, monoclinic, or amorphous) and preparation methods, with typical estimates from 5-7 eV.<ref>{{cite journal |first=Jane P |last=Chang |coauthors=You-Sheng Lin; Karen Chu |title=Rapid thermal chemical vapor deposition of zirconium oxide for metal-oxide-semiconductor field effect transistor application |journal=Journal of Vacuum Science & Technology B: |volume=19|issue=5 |pages=1782–1787 |year=2001| doi = 10.1116/1.1396639}}</ref>
			Three phases are known: monoclinic below 1170&nbsp;°C, tetragonal between 1170&nbsp;°C and 2370&nbsp;°C, and cubic above 2370&nbsp;°C.<ref>R. Stevens, 1986. Introduction to Zirconia. Magnesium Elektron Publication No 113</ref> The trend is for higher symmetry at higher temperatures, as is usually the case. A small percentage of the oxides of calcium or yttrium stabilize in the cubic phase.<ref name="Ullmann"/> The very rare mineral ], {{chem2|(Zr,Ti,Ca)O2}}, is ]. Unlike {{chem2|TiO2}}, which features six-coordinated titanium in all phases, monoclinic zirconia consists of seven-coordinated zirconium centres. This difference is attributed to the larger size of the zirconium atom relative to the titanium atom.<ref>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. {{ISBN|0-7506-3365-4}}</ref>
			===Chemical reactions===
	A special case of zirconia is that of ] or TZP, which is indicative of polycrystalline zirconia composed of only the metastable tetragonal phase.
			Zirconia is chemically unreactive. It is slowly attacked by concentrated ] and ]. When heated with carbon, it converts to ]. When heated with carbon in the presence of chlorine, it converts to ]. This conversion is the basis for the purification of zirconium metal and is analogous to the ].
			==Engineering properties <!--linked from 'Yttria-stabilized zirconia'-->==
			]
			Zirconium dioxide is one of the most studied ] materials. {{chem2|ZrO2}} adopts a ] ] at room temperature and transitions to ] and ] at higher temperatures. The change of volume caused by the structure transitions from tetragonal to monoclinic to cubic induces large stresses, causing it to crack upon cooling from high temperatures.<ref>{{cite journal |last1=Platt |first1=P. |last2=Frankel |first2=P. |last3=Gass |first3=M. |last4=Howells |first4=R. |last5=Preuss |first5=M. |title=Finite element analysis of the tetragonal to monoclinic phase transformation during oxidation of zirconium alloys |journal=Journal of Nuclear Materials |date=November 2014 |volume=454 |issue=1–3 |pages=290–297 |doi=10.1016/j.jnucmat.2014.08.020 |bibcode=2014JNuM..454..290P |doi-access=free}}</ref> When the zirconia is ] some other oxides, the tetragonal and/or cubic phases are stabilized. Effective dopants include ] (MgO), ] ({{chem2|Y2O3}}, yttria), ] ({{chem2|CaO}}), and ] ({{chem2|Ce2O3}}).<ref name=evans>{{cite journal |author=Evans, A.G. |author2=Cannon, R.M. |title=Toughening of brittle solids by martensitic transformations |journal=Acta Metall. |volume=34 |page=761 |year=1986 |doi=10.1016/0001-6160(86)90052-0 |url=https://zenodo.org/record/1253774}}</ref>
			Zirconia is often more useful in its phase 'stabilized' state. Upon heating, zirconia undergoes disruptive phase changes. By adding small percentages of yttria, these phase changes are eliminated, and the resulting material has superior thermal, mechanical, and electrical properties. In some cases, the tetragonal phase can be ]. If sufficient quantities of the metastable tetragonal phase is present, then an applied stress, magnified by the ] at a crack tip, can cause the tetragonal phase to convert to monoclinic, with the associated volume expansion. This phase transformation can then put the crack into compression, retarding its growth, and enhancing the ]. This mechanism, known as ], significantly extends the reliability and lifetime of products made with stabilized zirconia.<ref name=evans/><ref>{{cite journal |author=Porter, D.L. |author2=Evans, A.G. |author3=Heuer, A.H. |title=Transformation toughening in PSZ |journal=Acta Metall. |volume=27 |page=1649 |year=1979 |doi=10.1016/0001-6160(79)90046-4}}</ref>
			The {{chem2|ZrO2}} ] is dependent on the phase (cubic, tetragonal, monoclinic, or amorphous) and preparation methods, with typical estimates from 5–7&nbsp;eV.<ref>{{cite journal |first=Jane P. |last=Chang |author2=You-Sheng Lin |author3=Karen Chu |title=Rapid thermal chemical vapor deposition of zirconium oxide for metal–oxide–semiconductor field effect transistor application |journal=] |volume=19|issue=5 |pages=1782–1787 |year=2001 |doi=10.1116/1.1396639|bibcode=2001JVSTB..19.1782C }}</ref>
			A special case of zirconia is that of ], or TZP, which is indicative of polycrystalline zirconia composed of only the metastable tetragonal phase.
	==Uses==		==Uses==
			The main use of zirconia is in the production of hard ceramics, such as in dentistry,<ref>{{cite web |url=https://www.usgs.gov/centers/nmic/zirconium-and-hafnium-statistics-and-information |title=Zirconium and Hafnium Statistics and Information |first=Joseph |last=Gambogi |website=USGS National Minerals Information Center |access-date=5 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20180218030521/https://minerals.usgs.gov/minerals/pubs/commodity/zirconium/ |archive-date=18 February 2018}}</ref> with other uses including as a ] on particles of ] pigments,<ref name="Ullmann"/> as a ] material, in ], ]s, and ].
	The ] also has a very low ], which has led to its use as a ] or TBC in ] and ]s to allow operation at higher temperatures. ] the higher the operation temperature of an engine, the greater the possible efficiency (see ]). As of 2004, a great deal of research is ongoing to improve the quality and durability of these coatings.
	It is used as a ] material, in ], ]s, ] and ]s. Stabilized zirconia is used in ]s and ] membranes because it has the ability to allow ] ]s to move freely through the crystal structure at high temperatures. This high ] (and a low electronic conductivity) makes it one of the most useful ].		Stabilized zirconia is used in ]s and ] membranes because it has the ability to allow ] ]s to move freely through the crystal structure at high temperatures. This high ] (and a low electronic conductivity) makes it one of the most useful ]s.<ref name="Ullmann"/> Zirconium dioxide is also used as the ] in ]s.
			Zirconia is a precursor to the electroceramic ] (''PZT''), which is a high-κ dielectric, which is found in myriad components.
	This material is also used in the manufacture of subframes for the construction of ]s such as ] and ], which are then veneered with a conventional ] ].<ref>{{cite journal |first=Panos |last=Papaspyridakos |coauthor=Kunal Lal |title=Complete arch implant rehabilitation using subtractive rapid prototyping and porcelain fused to zirconia prosthesis: A clinical report |journal=The Journal of Prosthetic Dentistry |volume=100 |issue=3 |year=2008 |pages=165–172 |doi=10.1016/S0022-3913(08)00110-8 |pmid=18762028}}</ref>
			===Niche uses===
	Zirconium dioxide can occur as a white powder which possesses both ]ic and ] properties. On account of its infusibility and brilliant luminosity when ], it was used as an ingredient of sticks for ].
			The very low ] of ] also has led to its use as a ], or TBC, in ] and ]s to allow operation at higher temperatures.<ref>{{cite web |url=https://studylib.net/doc/12141427 |title=Thermal-barrier coatings for more efficient gas-turbine engines |website=studylib.net |language=en |access-date=2018-08-06}}</ref> Thermodynamically, the higher the operation temperature of an engine, ]. Another low-thermal-conductivity use is as a ceramic fiber insulation for crystal growth furnaces, fuel-cell stacks, and infrared heating systems.
			This material is also used in dentistry in the manufacture of subframes for the construction of ]s such as ] and ], which are then veneered with a conventional ] ] for aesthetic reasons, or of strong, extremely durable dental prostheses constructed entirely from monolithic zirconia, with limited but constantly improving aesthetics.<ref>{{cite journal |first=Panos |last=Papaspyridakos |author2=Kunal Lal |title=Complete arch implant rehabilitation using subtractive rapid prototyping and porcelain fused to zirconia prosthesis: A clinical report |journal=The Journal of Prosthetic Dentistry |volume=100 |issue=3 |year=2008 |pages=165–172 |doi=10.1016/S0022-3913(08)00110-8 |pmid=18762028|doi-access=free }}</ref><ref name=":0">{{Cite journal|last1=Kastyl|first1=Jaroslav|last2=Chlup|first2=Zdenek|last3=Stastny|first3=Premysl|last4=Trunec|first4=Martin|date=2020-08-17|title=Machinability and properties of zirconia ceramics prepared by gelcasting method|url=https://doi.org/10.1080/17436753.2019.1675402|journal=Advances in Applied Ceramics|volume=119|issue=5–6|pages=252–260|doi=10.1080/17436753.2019.1675402|bibcode=2020AdApC.119..252K |hdl=11012/181089 |s2cid=210795876 |issn=1743-6753|hdl-access=free}}</ref> Zirconia stabilized with ] (yttrium oxide), known as ], can be used as a strong base material in some full ceramic crown restorations.<ref name=":0" /><ref>{{cite book |editor-last1=Shen |editor-first1=James |title=Advanced ceramics for dentistry |date=2013 |publisher=Elsevier/BH |location=Amsterdam |isbn=978-0123946195 |page=271 |edition=1st}}</ref>
	Zirconia is also an important ] material that is being investigated for potential applications as an insulator in ]s in future ] devices.
			Transformation-toughened zirconia is used to make ].<ref>{{cite web |url=https://powder.samaterials.com/overview-of-zirconium-dioxide-powder-preparation-uses-safety.html |title=Overview of Zirconium Dioxide Powder: Preparation, Uses, and Safety |website=Stanford Advanced Materials |access-date=Sep 15, 2024}}</ref> Because of the hardness, ceramic-edged cutlery stays sharp longer than steel edged products.<ref>{{cite news |url=https://asia.kyocera.com/products/kitchen/basic_series/serrated_12cm_blade.html |title=Serrated 12cm blade Ceramic Kitchen Knives and Tools |newspaper=Ceramic Kitchen Knives and Tools &#124; Kyocera Asia-Pacific |access-date=4 August 2021}}</ref>
			Due to its infusibility and brilliant luminosity when ], it was used as an ingredient of sticks for ].{{citation needed|date=June 2012}}
			Zirconia has been proposed to ] ] and oxygen from the ] to provide both fuel and oxidizer that could be used as a store of chemical energy for use with surface transportation on Mars. ]s have been suggested for early surface transportation use, as both carbon monoxide and oxygen can be straightforwardly produced by zirconia electrolysis without requiring use of any of the Martian water resources to obtain hydrogen, which would be needed for the production of methane or any hydrogen-based fuels.<ref name=landis2001>{{cite journal |first1=Geoffrey A. |last1=Landis |first2=Diane L. |last2=Linne |title=Mars Rocket Vehicle Using In Situ Propellants |journal=Journal of Spacecraft and Rockets |date=2001 |volume=38 |issue=5 |pages=730–35 |doi=10.2514/2.3739|bibcode=2001JSpRo..38..730L }}</ref>
			Zirconia can be used as ]<ref>{{cite journal |last1=Kohno |first1=Yoshiumi |last2=Tanaka |first2=Tsunehiro |last3=Funabiki |first3=Takuzo |last4=Yoshida |first4=Satohiro |title=Identification and reactivity of a surface intermediate in the photoreduction of CO2 with H2 over ZrO2 |journal=Journal of the Chemical Society, Faraday Transactions |date=1998 |volume=94 |issue=13 |pages=1875–1880 |doi=10.1039/a801055b}}</ref> since its high ] (~ 5 eV)<ref>{{cite journal |last1=Gionco |first1=Chiara |last2=Paganini |first2=Maria C. |last3=Giamello |first3=Elio |last4=Burgess |first4=Robertson |last5=Di Valentin |first5=Cristiana |last6=Pacchioni |first6=Gianfranco |title=Cerium-Doped Zirconium Dioxide, a Visible-Light-Sensitive Photoactive Material of Third Generation |journal=The Journal of Physical Chemistry Letters |date=15 January 2014 |volume=5 |issue=3 |pages=447–451 |doi=10.1021/jz402731s |pmid=26276590 |hdl=2318/141649 |hdl-access=free}}</ref> allows the generation of high-energy electrons and holes. Some studies demonstrated the activity of doped zirconia (in order to increase visible light absorption) in degrading organic compounds<ref>{{cite journal |last1=Yuan |first1=Quan |last2=Liu |first2=Yang |last3=Li |first3=Le-Le |last4=Li |first4=Zhen-Xing |last5=Fang |first5=Chen-Jie |last6=Duan |first6=Wen-Tao |last7=Li |first7=Xing-Guo |last8=Yan |first8=Chun-Hua |title=Highly ordered mesoporous titania–zirconia photocatalyst for applications in degradation of rhodamine-B and hydrogen evolution |journal=Microporous and Mesoporous Materials |date=August 2009 |volume=124 |issue=1–3 |pages=169–178 |doi=10.1016/j.micromeso.2009.05.006|bibcode=2009MicMM.124..169Y }}</ref><ref>{{cite journal |last1=Bortot Coelho |first1=Fabrício |last2=Gionco |first2=Chiara |last3=Paganini |first3=Maria |last4=Calza |first4=Paola |last5=Magnacca |first5=Giuliana |title=Control of Membrane Fouling in Organics Filtration Using Ce-Doped Zirconia and Visible Light |journal=Nanomaterials |date=3 April 2019 |volume=9 |issue=4 |pages=534 |doi=10.3390/nano9040534| pmc=6523972 |pmid=30987140 |doi-access=free}}</ref> and reducing ] from wastewaters.<ref>{{cite journal |last1=Bortot Coelho |first1=Fabrício Eduardo |last2=Candelario |first2=Victor M. |last3=Araújo |first3=Estêvão Magno Rodrigues |last4=Miranda |first4=Tânia Lúcia Santos |last5=Magnacca |first5=Giuliana |title=Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light |journal=Nanomaterials |date=18 April 2020 |volume=10 |issue=4 |pages=779 |doi=10.3390/nano10040779 |pmid=32325680 |pmc=7221772 |issn=2079-4991 |doi-access=free}}</ref>
			Zirconia is also a potential ] material with potential applications as an insulator in ]s.
			Zirconia is also employed in the deposition of ]s; it is a high-index material usable from the ] to the ], due to its low absorption in this spectral region. In such applications, it is typically deposited by ].<ref>{{cite web |title=Zirconium Oxide Zr02 For Optical Coating |website=Materion |url=http://materion.com/ResourceCenter/ProductData/InorganicChemicals/Oxides/BrochuresAndDataSheets/ZirconiumOxideZr02.aspx |access-date=April 30, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131020212333/http://materion.com/ResourceCenter/ProductData/InorganicChemicals/Oxides/BrochuresAndDataSheets/ZirconiumOxideZr02.aspx |archive-date=October 20, 2013}}</ref>
			In jewelry making, some watch cases are advertised as being "black zirconium oxide".<ref>{{cite web |url=https://www.omegawatches.com/watches/speedmaster/moonwatch/omega-co-axial-chronograph/31192445101003/ |title=Omega Co-Axial Chronograph 44.25 mm |website=OMEGA Watches |language=en-US |access-date=2016-03-27 |url-status=live |archive-url=https://web.archive.org/web/20160326103447/http://www.omegawatches.com/watches/speedmaster/moonwatch/omega-co-axial-chronograph/31192445101003/ |archive-date=2016-03-26}}</ref> In 2015 Omega released a fully {{chem2|ZrO2}} watch named "The Dark Side of The Moon"<ref>{{Cite web |url=https://www.omegawatches.com/watches/speedmaster/moonwatch/dark-side-of-the-moon/product/ |title=Speedmaster Moonwatch Dark Side Of The Moon {{!}} OMEGA |website=Omega |language=en-GB |access-date=2018-02-08 |url-status=live |archive-url=https://web.archive.org/web/20180209063908/https://www.omegawatches.com/watches/speedmaster/moonwatch/dark-side-of-the-moon/product/ |archive-date=2018-02-09}}</ref> with ceramic case, bezel, pushers, and clasp, advertising it as four times harder than stainless steel and therefore much more resistant to scratches during everyday use.
			In ], tungsten electrodes containing 1% ] oxide (a.k.a. ]) instead of 2% thorium have good arc starting and current capacity, and are not radioactive.<ref name="electrode-selection">{{cite web |date=2009 |title=Tungsten Selection |url=https://www.arc-zone.com/pdf/SelectingTungsten.pdf |access-date=2015-06-15 |website=Arc-Zone.com |location=Carlsbad, ]}}</ref>
	===Diamond simulant===		===Diamond simulant===
	{{main|Cubic zirconia}}		{{Main|Cubic zirconia}}
	]		]
			Single crystals of the cubic phase of zirconia are commonly used as ] in ]. Like diamond, cubic zirconia has a cubic crystal structure and a high ]. Visually discerning a good quality cubic zirconia gem from a diamond is difficult, and most jewellers will have a thermal conductivity tester to identify cubic zirconia by its low ] (diamond is a very good thermal conductor). This state of zirconia is commonly called ''cubic zirconia'', ''CZ'', or ''zircon'' by ], but the last name is not chemically accurate. ] is actually the mineral name for naturally occurring ] ({{chem2|ZrSiO4}}).
	Single crystals of the cubic phase of zirconia are commonly used as ] in ]. Like diamond, cubic zirconia has a cubic crystal structure and a high ]. Visually discerning a good quality cubic zirconia gem from a diamond is difficult, and most jewellers will have a thermal conductivity tester to identify cubic zirconia by its low ] (diamond is a very good thermal conductor). This state of zirconia is commonly called "cubic zirconia," "CZ," or "zircon" by ], but the last name is not chemically accurate. ] is actually the mineral name for naturally occurring ] (ZrSiO<sub>4</sub>).
	==See also==		==See also==
	*]		* ]
	*]		* ]
			* ], emitting spectral lines of zirconium monoxide
	*]
			* ]
	==References==		==References==
	{{reflist|2}}		{{Reflist}}
	==Further reading==		==Further reading==
	*{{cite book|last = Green|first = D.J.|coauthors = Hannink, R.; Swain, M.V.|year = 1989		* {{cite book |last1=Green |first1=D. J. |last2=Hannink |first2=R. |last3=Swain |first3=M. V. |year=1989 |title=Transformation Toughening of Ceramics |location=Boca Raton |publisher=CRC Press |isbn=0-8493-6594-5}}
			* {{cite book |editor1-last=Heuer |editor1-first=A.H. |editor2-last=Hobbs |editor2-first=L.W. |title=Science and Technology of Zirconia |series=Advances in Ceramics |volume=3 |page=475 |publisher=American Ceramic Society |location=Columbus, OH |date=1981}}
	| title = Transformation Toughening of Ceramics|location = Boca Raton|publisher = CRC Press| isbn = 0-8493-6594-5}}
	*Heuer, A.H., Hobbs, L.W., Eds., ''Science and Technology of Zirconia'', Adv. Ceram., Vol. 3, p.&nbsp;475 (ACerS, Columbus, OH 1981)		* {{cite book |editor1-last=Claussen |editor1-first=N. |editor2-last=Rühle |editor2-first=M. |editor3-last=Heuer |editor3-first=A.H. |title=Proc. 2nd Int'l Conf. on Science and Technology of Zirconia |series=Advances in Ceramics |volume=11 |publisher=American Ceramic Society |location=Columbus, OH |date=1984}}
	*Claussen, N., Rühle, M., Heuer, A.H., ''Proc. 2nd Int'l Conf. on Science and Technology of Zirconia'', Adv. Ceram., Vol. 11 (ACerS, Columbus, OH 1984)
	==External links==		==External links==
	*		*
	{{Zirconium compounds}}		{{Zirconium compounds}}
			{{Oxides}}
			{{Authority control}}
			]
	{{DEFAULTSORT:Zirconium Dioxide}}
	]		]
	]		]
	]		]
	]		]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]