Production and Chemical Properties
- Zirconia is produced by calcining zirconium compounds.
- Zirconia has the chemical formula ZrO.
- Its molar mass is 123.218 g/mol.
- Zirconia appears as a white powder.
- Zirconia is chemically unreactive.
- It is slowly attacked by concentrated hydrofluoric acid and sulfuric acid.
- It converts to zirconium carbide when heated with carbon.
- In the presence of chlorine, it converts to zirconium(IV) chloride.
- This conversion is used for the purification of zirconium metal.
Structure
- Zirconia has three phases: monoclinic, tetragonal, and cubic.
- The higher the temperature, the higher the symmetry of the structure.
- The cubic phase can be stabilised by adding oxides of calcium or yttrium.
- Monoclinic zirconia consists of seven-coordinated zirconium centers.
- The mineral tazheranite is cubic and contains Zr, Ti, and Ca.
Engineering Properties
- Zirconia undergoes phase changes from monoclinic to tetragonal to cubic.
- The change in volume during these transitions can cause cracking.
- Stabilised zirconia with dopants like yttria has superior properties.
- Transformation toughening enhances fracture toughness.
- Zirconia has a band gap dependent on its phase and preparation methods.
Uses
- Zirconia is used in the production of hard ceramics.
- It is used in dentistry for dental restorations and prostheses.
- Zirconia is used in oxygen sensors and fuel cell membranes.
- It is a precursor to lead zirconate titanate, a high-κ dielectric.
- Zirconia is used as a thermal barrier coating in engines.
Applications, Properties, and Research
- Zirconium dioxide is used in watch cases, gas tungsten arc welding electrodes, and thermal-barrier coatings for gas-turbine engines.
- It is used in dental ceramics, kitchen knives, and tools.
- Zirconium dioxide is four times harder than stainless steel.
- It undergoes phase transformations during oxidation and exhibits transformation toughening.
- Zirconium dioxide has various industrial and scientific applications, such as catalysts and photocatalysts.
- Research has been conducted on the properties, machinability, and applications of zirconia ceramics.
- Studies have been done on the phase transformation during oxidation of zirconium alloys and the toughening of zirconia through martensitic transformations.
- Rapid prototyping and porcelain fused to zirconia prosthesis have been explored for dental applications.
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 stabilised cubic structured zirconia, cubic zirconia, is synthesised in various colours for use as a gemstone and a diamond simulant.
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| Names | |
|---|---|
| IUPAC names Zirconium dioxide Zirconium(IV) oxide | |
| Other names Zirconia Baddeleyite | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.013.844 |
| EC Number |
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PubChem CID | |
| 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 formation (ΔfH⦵298) | –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) | > 8.8 g/kg (oral, rat) |
| Safety data sheet (SDS) | MSDS |
| Related compounds | |
Other anions | Zirconium disulfide |
Other cations | Titanium dioxide Hafnium dioxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
