The red component of color television cathode ray tubes is typically emitted from an yttria () or yttrium oxide sulfide () host lattice doped with europium (III) cation (Eu) phosphors. The red color itself is emitted from the europium while the yttrium collects energy from the electron gun and passes it to the phosphor. Yttrium compounds can serve as host lattices for doping with different lanthanide cations. Tb can be used as a doping agent to produce green luminescence. As such yttrium compounds such as yttrium aluminium garnet (YAG) are useful for phosphors and are an important component of white LEDs.
Yttria is used as a sintering additive in the production of porous silicon nitride.
Yttrium compounds are used as a catalyst for ethylene polymerization. As a metal, yttrium is used on the electrodes of some high-performance spark plugs. Yttrium is used in gas mantles for propane lanterns as a replacement for thorium, which is radioactive.