Zirconium dioxide
Names | |
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IUPAC names
Zirconium dioxide
Zirconium(IV) oxide | |
Other names
Zirconia
Baddeleyite | |
Identifiers | |
3D model (
JSmol ) |
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ChemSpider | |
ECHA InfoCard
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100.013.844 |
EC Number |
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PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
ZrO 2 | |
Molar mass | 123.218 g/mol |
Appearance | white powder |
Density | 5.68 g/cm3 |
Melting point | 2,715 °C (4,919 °F; 2,988 K) |
Boiling point | 4,300 °C (7,770 °F; 4,570 K) |
negligible | |
Solubility | soluble in HF, and hot H2SO4 |
Refractive index (nD)
|
2.13 |
Thermochemistry | |
Std molar
entropy (S⦵298) |
50.3 J K−1 mol−1 |
Std enthalpy of (ΔfH⦵298)formation |
–1080 kJ/mol |
Hazards | |
GHS labelling: | |
Warning | |
H315, H319, H335 | |
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
Flash point | Non-flammable |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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> 8.8 g/kg (oral, rat) |
Safety data sheet (SDS) | MSDS |
Related compounds | |
Other anions
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Zirconium disulfide |
Other cations
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Hafnium dioxide
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Zirconium dioxide (ZrO
2), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stabilized cubic structured zirconia, cubic zirconia, is synthesized in various colours for use as a gemstone and a diamond simulant.[1]
Production, chemical properties, occurrence
Zirconia is produced by calcining zirconium compounds, exploiting its high thermostability.[2]
Structure
Three phases are known: monoclinic below 1170 °C, tetragonal between 1170 °C and 2370 °C, and cubic above 2370 °C.[3] 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.[2] The very rare mineral tazheranite, (Zr,Ti,Ca)O2, is cubic. Unlike 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.[4]
Chemical reactions
Zirconia is chemically unreactive. It is slowly attacked by concentrated hydrofluoric acid and sulfuric acid. When heated with carbon, it converts to zirconium carbide. When heated with carbon in the presence of chlorine, it converts to zirconium(IV) chloride. This conversion is the basis for the purification of zirconium metal and is analogous to the Kroll process.
Engineering properties
Zirconium dioxide is one of the most studied
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
The ZrO2 band gap is dependent on the phase (cubic, tetragonal, monoclinic, or amorphous) and preparation methods, with typical estimates from 5–7 eV.[8]
A special case of zirconia is that of tetragonal zirconia polycrystal, or TZP, which is indicative of polycrystalline zirconia composed of only the metastable tetragonal phase.
Uses
The main use of zirconia is in the production of hard ceramics, such as in dentistry,
Stabilized zirconia is used in
Zirconia is a precursor to the electroceramic lead zirconate titanate (PZT), which is a high-κ dielectric, which is found in myriad components.
Niche uses
The very low
This material is also used in dentistry in the manufacture of subframes for the construction of
Transformation-toughened zirconia is used to make ceramic knives. Because of the hardness, ceramic-edged cutlery stays sharp longer than steel edged products.[14]
Due to its infusibility and brilliant luminosity when incandescent, it was used as an ingredient of sticks for limelight.[citation needed]
Zirconia has been proposed to
Zirconia can be used as photocatalyst[16] since its high band gap (~ 5 eV)[17] 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[18][19] and reducing Cr(VI) from wastewaters.[20]
Zirconia is also a potential high-κ dielectric material with potential applications as an insulator in transistors.
Zirconia is also employed in the deposition of optical coatings; it is a high-index material usable from the near-UV to the mid-IR, due to its low absorption in this spectral region. In such applications, it is typically deposited by PVD.[21]
In jewelry making, some watch cases are advertised as being "black zirconium oxide".[22] In 2015 Omega released a fully ZrO2 watch named "The Dark Side of The Moon"[23] 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
Diamond simulant
Single crystals of the cubic phase of zirconia are commonly used as
See also
- Quenching
- Sintering
- S-type star, emitting spectral lines of zirconium monoxide
- Yttria-stabilized zirconia
References
- ISSN 0079-6786.
- ^
- ^ R. Stevens, 1986. Introduction to Zirconia. Magnesium Elektron Publication No 113
- ISBN 0-7506-3365-4
- .
- ^ .
- .
- .
- ^ Gambogi, Joseph. "Zirconium and Hafnium Statistics and Information". USGS National Minerals Information Center. Archived from the original on 18 February 2018. Retrieved 5 May 2018.
- ^ "Thermal-barrier coatings for more efficient gas-turbine engines". studylib.net. Retrieved 2018-08-06.
- PMID 18762028.
- ^ S2CID 210795876.
- ISBN 978-0123946195.
- ^ "Serrated 12cm blade Ceramic Kitchen Knives and Tools". Ceramic Kitchen Knives and Tools | Kyocera Asia-Pacific. Retrieved 4 August 2021.
- doi:10.2514/2.3739.
- doi:10.1039/a801055b.
- PMID 26276590.
- .
- PMID 30987140.
- PMID 32325680.
- ^ "Zirconium Oxide Zr02 For Optical Coating". Materion. Archived from the original on October 20, 2013. Retrieved April 30, 2013.
- ^ "Omega Co-Axial Chronograph 44.25 mm". OMEGA Watches. Archived from the original on 2016-03-26. Retrieved 2016-03-27.
- ^ "Speedmaster Moonwatch Dark Side Of The Moon | OMEGA". Omega. Archived from the original on 2018-02-09. Retrieved 2018-02-08.
- ^ "Tungsten Selection" (PDF). Arc-Zone.com. Carlsbad, California. 2009. Retrieved 2015-06-15.
Further reading
- Green, D. J.; Hannink, R.; Swain, M. V. (1989). Transformation Toughening of Ceramics. Boca Raton: CRC Press. ISBN 0-8493-6594-5.
- Heuer, A.H.; Hobbs, L.W., eds. (1981). Science and Technology of Zirconia. Advances in Ceramics. Vol. 3. Columbus, OH: American Ceramic Society. p. 475.
- Claussen, N.; Rühle, M.; Heuer, A.H., eds. (1984). Proc. 2nd Int'l Conf. on Science and Technology of Zirconia. Advances in Ceramics. Vol. 11. Columbus, OH: American Ceramic Society.