Used as a red phosphor in cathode ray tubes and fluorescent lamps, providing bright red emission when excited. Commonly doped into materials like yttrium oxide (Y₂O₃:Eu) for display and lighting applications. Employed in anti-counterfeiting inks due to its luminescent properties under UV light. Also utilized in medical imaging and as a tracer in biological assays. Serves as a dopant in solid-state lasers and LED phosphors for color tuning. Widely applied in research for developing luminescent sensors and optoelectronic devices.