Used as a key component in phosphors for color television screens and LED lighting, enabling bright red and green emissions. Employed in ceramics and glass to improve thermal stability and resistance to cracking under temperature changes. Serves as a host material for rare-earth dopants in solid-state lasers and optical coatings. Applied in electronics as a high-k dielectric material in semiconductor devices. Also utilized in medical imaging and cancer treatment through yttrium-90 containing compounds for targeted radiotherapy.