Zirconia redirects here. For the Sailor Moon character, see Dead Moon Circus. is the title of a Japanese Media franchise created by Naoko Takeuchi. The are a group of fictional Antagonists from the Sailor Moon Metaseries.

Thermodynamic data
IUPAC name	Zirconium dioxide; Zirconium(IV) oxide
Other names	Zirconia; Baddeleyite
Identifiers
CAS number	[1314-23-4]
Properties
Molecular formula	ZrO2
Molar mass	123. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general Baddeleyite is a rare zirconium oxide Mineral ( Zr[[oxygen O]]2 or Zirconia) occurring in a variety of Monoclinic prismatic crystal CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) 22 g/mol
Appearance	white solid
Density	5. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 89 g/cm³, solid
Melting point	2715 °C
Boiling point	°C
Solubility in water	Insoluble
Thermochemistry
Std enthalpy of formation ΔfHo298	−1080 kJ/mol
Standard molar entropy So298	50. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Water is a common Chemical substance that is essential for the survival of all known forms of Life. The standard enthalpy of formation or "standard heat of formation" of a compound is the change of Enthalpy that accompanies the formation of 1 mole of a In Chemistry, the standard molar entropy is the Entropy content of one mole of substance under standard conditions (not standard temperature and pressure 3 J. K−1. mol−1
Hazards
EU classification	not listed
Related compounds
Other anions	Zirconium disulfide
Other cations	Titanium dioxide; Hafnium dioxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Zirconium dioxide (ZrO₂), sometimes known as zirconia, is a white crystalline oxide of zirconium. Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws regulations and administrative provisions relating to the classification packaging and labelling An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Titanium dioxide, also known as titanium(IV oxide or titania, is the naturally occurring Oxide of Titanium, chemical formula Ti[[oxygen Hafnium dioxide is the Inorganic compound with the formula Hf[[Oxygen O]]2 In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element Zirconium (zɚˈkoʊniəm /ˌzɝˈkoʊniəm/ is a Chemical element with the symbol Zr and Atomic number 40 Its most naturally occurring form, with a monoclinic crystalline structure, is the rare mineral, baddeleyite. In Crystallography, the monoclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three vectors. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Baddeleyite is a rare zirconium oxide Mineral ( Zr[[oxygen O]]2 or Zirconia) occurring in a variety of Monoclinic prismatic crystal The high temperature cubic crystalline form, called 'cubic zirconia', is rarely, if ever, found in nature, but is synthesized in various colours for use as a gemstone. The cubic crystal system (or isometric) is a Crystal system where the Unit cell is in the shape of a Cube. Cubic zirconia (or CZ) the cubic crystalline form of Zirconium dioxide ( ZrO2) is a Mineral that is widely synthesized A gemstone or gem, also called a precious or semi-precious stone, is a piece of attractive Mineral, which &mdash when cut and polished &mdash The cubic crystal structured variety cubic zirconia is the best-known diamond simulant. Cubic zirconia (or CZ) the cubic crystalline form of Zirconium dioxide ( ZrO2) is a Mineral that is widely synthesized This article addresses the many imitations of diamond For a broader discussion of diamonds see Diamond.

Contents 1 Ceramic and engineering properties 2 Diamond Substitute 3 Patents 4 See also 5 References 6 External links

Ceramic and engineering properties

Zirconium dioxide is one of the most studied ceramic materials. The word ceramic is derived from the Greek word κεραμικός ( keramikos) Pure ZrO₂ has a monoclinic crystal structure at room temperature and transitions to tetragonal and cubic at increasing temperatures. In Crystallography, the monoclinic Crystal system is one of the 7 lattice Point groups A crystal system is described by three vectors. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. In Crystallography, the tetragonal Crystal system is one of the 7 lattice Point groups Tetragonal Crystal lattices result from stretching a cubic The cubic crystal system (or isometric) is a Crystal system where the Unit cell is in the shape of a Cube. The volume expansion caused by the cubic to tetragonal to monoclinic transformation induces very large stresses, and will cause pure ZrO₂ to crack upon cooling from high temperatures. Several different oxides are added to zirconia to stabilize the tetragonal and/or cubic phases: magnesium oxide (MgO), yttrium oxide, (Y₂O₃), calcium oxide (CaO), and cerium oxide (Ce₂O₃), amongst others. Magnesium oxide, or magnesia, is a white solid Mineral that occurs naturally as Periclase and is a source Yttrium oxide is Y 2 O 3 It is an air-stable white substance Yttrium oxide is used as a common starting material for both Calcium oxide ( CaO) commonly known as burnt lime, lime or quicklime, is a widely used Chemical compound. Cerium(IV oxide, ceric oxide, ceria, or sometimes simply cerium oxide or cerium dioxide, is a pale yellow-white powder CeO2

Zirconia is very useful in its 'stabilized' state. In some cases, the tetragonal phase can be metastable. Metastability is a general scientific concept which describes states of delicate equilibrium If sufficient quantities of the metastable tetragonal phase is present, then an applied stress, magnified by the stress concentration at a crack tip, can cause the tetragonal phase to convert to monoclinic, with the associated volume expansion. A stress concentration (often called stress raisers or stress risers) is a location in an object where stress is concentrated This phase transformation can then put the crack into compression, retarding its growth, and enhancing the fracture toughness. In Materials science, fracture toughness is a property which describes the ability of a material containing a crack to resist Fracture, and is one of the most important This mechanism is known as transformation toughening, and significantly extends the reliability and lifetime of products made with stabilized zirconia. A special case of zirconia is that of tetragonal zirconia polycrystaline or TZP, which is indicative of polycrystalline zirconia composed of only the metastable tetragonal phase. Yttria blends of approximately 3% are called Tetragonal Zirconia Polycrystal (TZP and have the finest grain size

The cubic phase of zirconia also has a very low thermal conductivity, which has led to its use as a thermal barrier coating or TBC in jet turbine and diesel engines to allow operation at higher temperatures. Cubic zirconia (or CZ) the cubic crystalline form of Zirconium dioxide ( ZrO2) is a Mineral that is widely synthesized Thermal barrier coatings are highly advanced material systems applied to metallic surfaces such as Gas turbine or aero-engine parts operating at elevated temperatures specific --->A jet engine is a Reaction engine that discharges a fast moving jet of Fluid to A diesel engine is an Internal combustion engine which operates using the Diesel cycle (named after Dr Thermodynamically the higher the operation temperature of an engine, the greater the possible efficiency (see Carnot heat engine). In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " A Carnot heat engine is a hypothetical engine that operates on the reversible Carnot cycle. As of 2004, a great deal of research is ongoing to improve the quality and durability of these coatings. It is used as a refractory material, in insulation, abrasives, enamels and ceramic glazes. A refractory is a material that retains its strength at high Temperatures ASTM C71 defines refractories as "non-metallic materials having those chemical and physical The term thermal insulation can refer to materials used to reduce the rate of Heat transfer, or the methods and processes used to reduce heat transfer An abrasive is a material often a Mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away In a discussion of Material science, enamel (or vitreous enamel or porcelain enamel in U Glaze is a layer or coating of a Vitreous substance which has been fired to fuse to a ceramic object to color decorate strengthen or waterproof it Stabilized zirconia is used in oxygen sensors and fuel cell membranes because it has the ability to allow oxygen ions to move freely through the crystal structure at high temperatures. An oxygen sensor, or lambda sensor is an electronic device that measures the proportion of Oxygen (O2 in the gas or liquid being analyzed A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge This high ionic conductivity (and a low electronic conductivity) makes it one of the most useful electroceramics. While Ceramics have traditionally been admired for their mechanical and thermal stability their unique Electrical, Optical and Magnetic properties have

The ZrO₂ bandgap is dependent on the phase (cubic, tetragonal, monoclinic, or amorphous) and preparation methods, with typical estimates from 5-7 eV. ^[1]

This material is also used in the manufacture of subframes for the construction of dental restorations such as crowns and bridges which are then veneered with a conventional feldspathic porcelain.

Zirconium dioxide can occur as a white powder which possesses both acidic and basic properties. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and On account of its infusibility and brilliant luminosity when incandescent, it was used as an ingredient of sticks for limelight. Limelight is a type of Stage lighting once used in Theatres and Music halls An intense illumination is created when an oxyhydrogen flame is directed

Zirconia is also an important dielectric material that is being investigated for potential applications as an insulator in transistors in future nanoelectronic devices.

Diamond Substitute

Single crystals of the cubic phase of zirconia are commonly used as a substitute for diamond in jewellery. Cubic zirconia (or CZ) the cubic crystalline form of Zirconium dioxide ( ZrO2) is a Mineral that is widely synthesized In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in Jewellery (also spelled jewelry, see spelling differences) is a personal Ornament, such as a necklace ring or bracelet made from Gemstones Like diamond, cubic zirconia has a cubic crystal structure and a high index of refraction. Cubic zirconia (or CZ) the cubic crystalline form of Zirconium dioxide ( ZrO2) is a Mineral that is widely synthesized The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Discerning a good quality cubic zirconia gem from a diamond is difficult, and most jewellers will have a thermal conductivity tester to identify cubic zircona by its low thermal conductivity (diamond is a very good thermal conductor). In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. This state of zirconia is commonly called "cubic zirconia," "CZ," or "zircon" by jewellers, but the last name is not chemically accurate. Jewellery (also spelled jewelry, see spelling differences) is a personal Ornament, such as a necklace ring or bracelet made from Gemstones Zircon is actually the mineral name for naturally occurring Zirconium silicate (ZrSiO₄). Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is Its transparent form is also used as a gemstone, and its opaque form as a refractory.

Patents

On August 7, 2006, Apple Computer filed a patent for using zirconia as casing for mobile devices. Events 322 BC - Battle of Crannon between Athens and Macedon following the death of Alexander the Great. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Apple Inc, ( formerly Apple Computer Inc, is an American Multinational corporation with a focus on designing and manufacturing Consumer electronics Future iPods likely will contain radios for Bluetooth and wide area wireless. iPod is a popular brand of Portable media players designed and marketed by Apple Inc Using zirconia rather than steel or aluminum for its radio transparency characteristics enables antennas to be hidden internally in the device. Additionally, some iPods with plastic fronts have been known to scratch easily. ^[2]

See also

• Yttria-stabilized zirconia

References

External links

• NIOSH Pocket Guide to Chemical Hazards

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