Yttrium oxide is Y2O3. It is an air-stable, white solid substance. Yttrium oxide is used as a common starting material for both materials science as well as inorganic compounds.
- In materials science: It is the most important yttrium compound and is widely used to make YVO4 europium and Y2O3 europium phosphors that give the red color in color TV picture tubes.
- Yttrium oxide is also used to make yttrium iron garnets, which are very effective microwave filters. In inorganic synthesis:Yttrium oxide is an important starting point for inorganic compounds. For organometallic chemistry it is converted to YCl3 in a reaction with concentrated hydrochloric acid and ammonium chloride.