Cerium is the most abundant of the rare earths. It is characterized chemically by having two valence states , the +3 cerous and +4 ceric states. Cerium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra high purity); metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder. The ceric state is the only non-trivalent rare earth ion stable in aqueous solutions. It is, therefore, strongly acidic. It is also a strong oxidizer. The cerous state closely resembles the other trivalent rare earths. The numerous commercial applications for cerium include metallurgy, glass and glass polishing, ceramics, catalysts, and in phosphors. In steel manufacturing it is used to remove free oxygen and sulfur by forming stable oxysulfides and by tying up undesirable trace elements, such as lead and antimony. It is considered to be the most efficient glass polishing agent for precision optical polishing. It is also used to decolor glass by keeping iron in its ferrous state. The ability of cerium-doped glass to block out ultra violet light is utilized in the manufacturing of medical glassware and aerospace windows. It is also used to prevent polymers from darkening in sunlight and to suppress discoloration of television glass. It is applied to optical components to improve performance. Cerium is also used in a variety of ceramics, including dental compositions and as a phase stabilizer in zirconia-based products. Ceria plays several catalytic roles. In catalytic converters it acts as a stabilizer for the high surface area alumina, as a promoter of the water-gas shift reaction, as an oxygen storage component and as an enhancer of the NOX reduction capability of Rhodium. Cerium is added to the dominant catalyst for the production of styrene from ethylbenezene to improve styrene formation. It is used in FCC catalysts containing zeolites to provide both catalytic reactivity in the reactor and thermal stability in the regenerator .

Cerium facts, including appearance, CAS #, and molecular formula and safety data, research and properties are

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Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Cerium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries.

Cerium is a Block F, Group 3, Period 6 element. The electronic configuration is [Xe]4f²6s². In its elemental form cerium's CAS number is 7440-45-1. The cerium atom has a radius of 182.5.pm and it's Van der Waals radius is 181.pm.

All elemental metals, compounds and solutions may be synthesized in ultra high purity (e.g. 99.999%) for laboratory standards, advanced electronic, metallurgy and optical materials and other high technology advantages. Information is provided for stable (non-radioactive) isotopes. Organo-Metallic Cerium compounds are soluble in organic or non-aqueous solvents. See Analytical Services for information on available certified chemical and physical analysis techniques including MS-ICP, X-Ray Diffraction, PSD and Surface Area (BET) analysis.

Cerium was first discovered by W. von Hisinger in 1903.

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Cerium Abundance. The following table shows the abundance of Cerium and each of its naturally occurring isotopes on Earth along with the atomic mass for each isotope.