Cerium dioxide (CAS: 1306-38-3)
Main Component:TREO≥99.9 %
Cerium(IV) oxide, also known as ceric oxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2.
Cerium(IV) oxide is formed by the calcination of cerium oxalate or cerium hydroxide.
Powdered ceria is slightly hygroscopic and will also absorb a small amount of carbon dioxide from the atmosphere.Cerium also forms cerium(III) oxide, Ce2O3, which is more stable at standard conditions for temperature and pressure than CeO2.
Cerium oxide has the fluorite structure, space group Fm3m, #225 containing 8 coordinate Ce4+ and 4 coordinate O2– . At high temperatures it can be reduced to a non-stoichiometric, anion deficient form that retains the fluorite lattice, CeO(2-x) where 0 < x < 0.28  The non stoichiometric form has a blue to black color, and exhibits both ionic and electronic conduction with ionic being the most significant at temperatures > 500 °C.
Cerium(IV) oxide is used in ceramics, to sensitize photosensitive glass, as a catalyst and as a catalyst support, to polish glass and stones, in lapidaryas an alternative to "jeweller's rouge". It is also known as "optician's rouge".
It is also used in the walls of self-cleaning ovens as a hydrocarbon catalyst during the high-temperature cleaning process.
While it is transparent for visible light, it absorbs ultraviolet radiation strongly, so it is a prospective replacement of zinc oxide and titanium dioxide in sunscreens, as it has lower photocatalytic activity. However, its thermal catalytic properties have to be decreased by coating the particles with amorphous silica or boron nitride. The use of these nanoparticles, which can penetrate the body and reach internal organs, has been criticized as unsafe.
Cerium oxide has found use in infrared filters, as an oxidizing species in catalytic converters and as a replacement for thorium dioxide in incandescent mantles