Applied in phosphor materials for LED backlighting and display screens with red emission, laser host materials for yttrium aluminum garnet (YAG) solid-state lasers, thermal barrier coatings for gas turbine blades to withstand extreme temperatures, optical coatings for infrared windows and lenses, ceramic additives for improving sintering and mechanical strength in cutting tools, dielectric layers in microelectronics and capacitors, scintillator materials for X-ray and gamma-ray detection in medical imaging, upconversion nanoparticles for bioimaging and photodynamic therapy, refractory materials for high-temperature furnace linings, and glass additives for increasing refractive index and chemical durability. Yttrium oxide provides excellent thermal stability (melting point 2439°C) and optical transparency.