Most of europium oxide is used as phosphor. Eu3 + is used as activator of red phosphor and Eu2 + is used as blue phosphor. Now Y2O2S: Eu3 + is the best phosphor in terms of luminous efficiency, coating stability and recovery cost. In addition to the improvement of the luminous efficiency and contrast, it is widely used. In recent years, europium oxide has also been used as stimulated emission phosphor in new X-ray medical diagnosis system. Europium oxide can also be used to make colored lenses and optical filters, magnetic bubble storage devices, control materials, shielding materials and structural materials of atomic reactors.