Used in research for luminescent materials and as a dopant in scintillation detectors for radiation measurement. Plays a role in nuclear medicine studies due to the favorable properties of lutetium isotopes. Also applied in catalysts for organic reactions and in the development of specialty glasses with high refractive indices. Investigated for use in photodynamic therapy and bioimaging because of its ability to form stable complexes with targeting ligands. Additionally, serves as a starting material for synthesizing other high-purity rare earth compounds and is applied in laser technology and advanced optical devices.