Used as a colorant in glass and cubic zirconia, producing yellow or red hues depending on lighting conditions. Employed in nuclear reactors as a neutron absorber due to its high thermal neutron capture cross-section. Utilized in solid-state lasers, particularly in yttrium-iron-garnet (YIG) and yttrium-lithium-fluoride (YLF) lasers, where it serves as a dopant for emitting infrared light. Applied in scientific research involving magnetic and optical properties of materials at low temperatures.