Terbium(III,IV) oxide is primarily used in advanced electronic and optical applications due to its unique redox properties and luminescence characteristics. It serves as a key component in solid-state devices, including sensors and capacitors, where mixed-valence rare earth oxides enhance performance. The compound is also employed in the production of green phosphors used in color television tubes, fluorescent lamps, and LED displays, where it efficiently converts ultraviolet or electron beam energy into visible green light. Additionally, it finds use in catalytic applications, especially in oxidation reactions, owing to its ability to shift between oxidation states. In research, it is explored for use in magneto-optical storage media and as a dopant in ceramic materials for improving thermal and electrical properties.