PRODUCT IDENTIFICATION

1306-38-3

H.S. CODE

TOXICITY

CLASSIFICATION

Cerium compound, Catalyst, Sunscreening agent

EXTRA NOTES

PHYSICAL AND CHEMICAL PROPERTIES

MELTING POINT

2600 C

SOLUBILITY IN WATER

6 (Mohs)

REFRACTIVE INDEX

EXTERNAL LINKS & GENERAL DESCRIPTION

Wikipedia Linking

Google Scholar Search

http://www.nanopartikel.info/
A huge market for nano-structured CeO₂ is cleaning and polishing of silicon wafers, which are required by the electronical industry for ultra modern chip systems and solar cells. Due to the reaction of CeO₂ with the processed material, it can be removed in a way extremely fine dosed which enables the manufacturing of ultra smooth surfaces, which pose the basic prerequisite for miniaturizing circuits. Together with aluminium oxide, cerium dioxide constitutes the material of first choice in the matter of chemical-mechanical polishing.
Nano-structured cerium dioxide, among other things, is used as an oxygen-storing diesel additive in vehicle exhaust catalysts. It still oxidises carbon monoxide and excess hydrocarbons into CO₂ when there is a temporary lack of oxygen in the exhaust mixture. During that process, CeO₂ is reduced to Ce₂O₃ that is re-oxidized later as soon as there is enough oxygen again in the exhaust gases. Aside from its role in exhaust catalysts where it mainly supports the much more active but also more expensive platinum, there is also a direct addition to the fuel intended. The cerium dioxide particles are supposed to reduce the fuel consumption as well as the emission of soot particles of diesel engines.
In fuel cells with other rare-earth metal oxides coated CeO₂ particles are applied to improve the oxygen ion conductivity and so to enable reduced operating temperatures.
Moreover, nano-structured CeO₂ poses an ideal UV absorber and is therefore used as an additive in lacquers and coatings for wood preservatives to enhance their UV stability.

http://www.1911encyclopedia.org/
Three oxides of cerium are known. The sesquioxide, Ce 2 O 3, is obtained by heating the carbonate in a current of hydrogen. It is a bluish-green powder, which on exposure rapidly combines with the oxygen of the air. By the addition of caustic soda to cerous salts, a white precipitate of cerous hydroxide is formed. Cerium dioxide, Ce02, is produced when cerium carbonate, nitrate, sulphate or oxalate is heated in air. It is a white or pale yellow compound, which becomes reddish on heating. Its specific gravity is 6.739, and its specific heat 0.0877. It is not reduced to the metallic condition on heating with carbon. Concentrated sulphuric acid dissolves this oxide, forming a yellowish solution and ozone. By suspending the precipitated cerous hydroxide in water and passing chlorine through the solution, a hydrated form of the dioxide, 2CeO 2.3H 2 O, is obtained, which is readily soluble in nitric and sulphuric acids, forming ceric salts, and in hydrochloric acid, where it forms cerous chloride, with liberation of chlorine. A higher hydrated oxide, CeO 3 xH 2 O, is formed by the interaction of cerous sulphate with sodium acetate and hydrogen peroxide

Local: Cerium is a metallic chemical element in group IIIb of periodic table; symbol Ce, soft, lustrous, ductile, iron-color metal with hexagonal or cubic crystalline structure; atomic number 58; atomic mass 140.12; melting point ca 799 C; boiling point ca 3,426 C; specific gravity 6.77 g/cm³ at 25 C; oxidation state +3 or +4; electronic config. [Xe]4f¹5d¹6s¹. It is the most abundant rare-earth element and the most reactive next to europium among the lanthanide group. Lanthanide (or lanthanoid) series are the group of rare-earth elements from lanthanum (atomic numbers 57) to 71; their chemical properties are similar to each other. The chemical properties of scandium and yttrium are also similar to the lanthanides; these group are often referred to "rare earth elements".

Cerium occurs chiefly in the minerals monazite and bastnaesite. The naturally occurring element is made up of the isotopes ¹³⁶Ce 0.193%, ¹³⁸Ce 0.250%, ¹⁴⁰Ce 88.58%, and ¹⁴²Ce 11.07% which is a radioactive alpha emitter having a half-life of 5×10¹⁵ years. Cerium is slightly harder than lead. It tarnishes rapidly in moist air but not in dry air. It oxidizes slowly in cold water and rapidly in hot water. It reacts rapidly with the solutions of alkalis and concentrated (or dilute) acids. Its oxidation valence is readily transferred form 3 to 4 if compressed or cooled. Its shell orbitals are relatively close between 4f and the outer. with Cerium of valence +3 is referred to as cerous, while with valence 4 is as ceric. Generally cerous salts are yellow to reddish while ceric slats are white. Minute particles of pure cerium or some iron-cerium alloy ignite if scratched and are used as the flint in cigarette and gas lighters. Cerium is used in making lamp mantles as incandescence is formed when burned. Cerium is allied to form malleable iron,  harder stainless steel, heat resistant magnesium and aluminium alloys and permanent magnets. It is also used as an opacifier and polisher in the glass industry, in cored carbon arcs to increase the brilliance especially for the motion picture industry, and as a liquid-liquid extraction agent to remove fission products from spent uranium fuel. Cerium compounds include;

• Ceric Oxide CeO₂ (CAS RN:1306-38-3): A pale-yellow to white powder; soluble in sulfuric acid, insoluble in dilute acid and water; used in ceramics and as a polish for optical glass. Catalyst for hydrocarbon cracking, styrene production and water-gas shift reaction. Thermal stabilizer for alumina and in chemical regenerating process.
• Ceric Sulfate Ce(SO₄)₂·xH₂O (CAS RN:13590-82-4): Yellow needles forming a basic salt with excess water; used in waterproofing, mildew-proofing, and in dyeing and printing textiles.
• Ceric Ammonium Nitrate (NH₄)₂Ce(NO₃)₆ (CAS RN: 16774-21-3): Oxidizer
• Ceric Ammonium Sulfate Ce(NH₄)₄(SO₄)₄ (CAS RN: 10378-47-9, Dihydrate): Oxidizer
• Ceric Hydroxide Ce(OH)₄ (CAS RN: 12014-56-1)
• Cerous Acetate Ce(OOCCH₃)₃·1.5H₂O (CAS RN: 537-00-8, Sesquihydrate)
• Cerous Bromide: CeBr₃ (CAS RN: 14457-87-5, )
• Cerous Carbonate Ce₂(CO₃)₃ (CAS RN: 537-01-9, 5838-16-7)
• Cerous Chloride CeCl₃ (CAS RN: 7790-86-5, 19423-76-8, 18618-55-8)
• Cerous Fluoride CeF₃: White hexagonal crystals, melting point 1460 C; used in arc carbons to increase the brilliance of carbon-arc lamps.
• Cerous Naphthenate: Used as drier/additive for paints, coatings and inks; catalyst for chemical reactions
• Cerous Nitrate Ce(NO₃)₃ (CAS RN:10294-41-4, Hydrate)
• Cerous Oxalate: Ce(C₂O₄)₃·xH₂O (CAS RN:139-42-4, 15750-47-7): Used in ceramics, glass, phosphors and pyrotechnics
• Cerous Perchlorate CeO₉Cl₃ (CAS RN: 14017-47-1)
• Cerous Phosphate CeH₂O₅P (CAS RN:13454-71-2)
• Cerous Silicide CeSi₂ (CAS RN:12014-85-6)
• Cerium Stearate Ce(C₁₈H₃₅O₂)₂ :White, waxy, inert powder, melting point 100-110 C; used in waterproofing compounds and drier for paint and ink.
• Cerous  Sulfide Ce₂S₃ (CAS RN:12014-93-6)

APPEARANCE

PURITY

99.9% min

PARTICLE SIZE

325 mesh

APPEARANCE

PURITY

99.0% min

PARTICLE SIZE

325 mesh