Used as a host material in phosphors for cathode ray tubes and LED lighting due to its ability to emit red light when doped with europium. Employed in solid oxide fuel cells as a stabilizer for zirconia, enhancing ionic conductivity at high temperatures. Applied in specialty glasses and ceramics to improve thermal shock resistance and refractive index. Utilized in coatings for jet engine turbine blades to provide thermal barrier protection. Also used in medical imaging and cancer treatment through yttrium-90 containing compounds derived from purified yttrium oxide.