cerias

Ceria, commonly called cerium oxide, is a chemical compound with the formula CeO2. The plural form cerias is sometimes used to refer to cerium oxide materials in their various forms. Ceria is a rare-earth oxide that crystallizes in a fluorite-type structure and is a pale beige to off-white powder at ambient conditions. It is chemically stable and has a high melting point.

A key feature of ceria is the reversible Ce4+/Ce3+ redox couple, which enables rapid exchange of oxygen. This oxygen storage capacity (OSC) allows ceria to participate in catalytic cycles and oxidation–reduction reactions. Nanostructured ceria, or nanoceria, often shows enhanced OSC due to increased surface area and defect density, improving catalytic performance in many applications.

Production of ceria typically starts from cerium-containing precursors derived from rare-earth ores such as monazite or bastnäsite. Through precipitation, precipitation-dissolution, and calcination, these precursors are converted to CeO2. Ceria also occurs naturally in minerals and is mined as a byproduct of processing rare-earth ores.

Major applications include polishing powders for glass and sapphire, where ceria provides a high-quality finish; catalysts in automotive exhaust systems and other oxidation reactions, where its OSC improves efficiency; and as a component or dopant in solid oxide fuel cells and other electrochemical devices. It is also used in photocatalysis, UV protection, and certain sensor technologies.

Safety considerations are generally modest, but inhalation of ceria dust can irritate the respiratory tract. Standard industrial hygiene practices and personal protective equipment are advised when handling powders in occupational settings.

See also: cerium oxide, nanoceria, solid oxide fuel cells.