ceria

Ceria, or cerium(IV) oxide, with the chemical formula CeO2, is a white to pale yellow solid that adopts a fluorite-type cubic crystal structure. In the lattice, cerium is primarily in the Ce4+ oxidation state, but reduction can create Ce3+ and oxygen vacancies, giving CeO2−x. This redox flexibility underlies its prominent catalytic and oxygen storage properties.

Ceria occurs commercially from rare earth minerals such as monazite and bastnäsite. It is produced by processing these concentrates to yield CeO2 and in various nanoscale forms for advanced applications. In practice, ceria’s properties depend on particle size, morphology, and the level of oxygen nonstoichiometry, which can be tuned by temperature and atmosphere.

Key properties and applications include its high oxygen storage capacity and the Ce4+/Ce3+ redox couple, which enable rapid uptake and release of oxygen. The material is widely used as a catalyst and catalyst support, notably in automotive three-way catalysts to balance oxidation and reduction reactions. Other common uses include polishing powders for glass and optics, additives in coatings, and components in solid oxide fuel cells and oxygen sensors. Doping ceria with zirconia (Ce1−xZrxO2) improves ionic conductivity and thermal stability for high-temperature applications.

Safety and handling considerations are typical of inorganic oxides: inhalation of fine dust can pose respiratory hazards; standard industrial hygiene practices should be followed. Ceria is generally regarded as having low acute toxicity. The mineral form CeO2 is also known as cerianite.