yttria

Yttria is the common name for yttrium oxide, a chemical compound with the formula Y2O3. It is a white, crystalline solid that is highly refractory and chemically stable. Yttria has a high melting point, typically cited around 2,400 °C, and a density near 5.0 g/cm³. At room temperature it adopts the cubic bixbyite crystal structure. It is insoluble in water and reacts only slowly with acids, forming yttrium salts upon dissolution.

Production and sources: Yttria is produced from yttrium-containing rare earth concentrates derived from minerals such as bastnäsite and monazite. The yttrium compounds are refined and converted to yttrium oxide through calcination and precipitation steps to yield the pure Y2O3 powder used in various applications.

Uses and applications: Yttria serves as a versatile host lattice in phosphors, notably in Y2O3:Eu3+ phosphors that emit red light and have been used in CRT displays and some LED technologies. It is also employed as a stabilizer in zirconia-based ceramics; adding yttria to zirconia (yttria-stabilized zirconia, or YSZ) helps maintain a hard, tough, high-temperature phase and is widely used in solid oxide fuel cells, oxygen sensors, and thermal barrier coatings. Additional uses include specialty ceramics, glass and ceramic glazes, and optical coatings where its refractive properties are advantageous.

Safety and handling: Yttria is of relatively low acute toxicity, but fine yttria powders can pose inhalation hazards and should be handled with appropriate industrial hygiene practices to minimize dust exposure. Standard precautions for inorganic powders apply.

See also: Yttrium compounds, yttria-stabilized zirconia, phosphor materials.