Terbium(III,IV) oxide is primarily used as an activator in phosphors for fluorescent lamps, television screens, and display panels, providing efficient green luminescence when excited by electrons or UV radiation. It enhances color rendering in trichromatic lighting systems, improving efficiency and reducing energy consumption. Additionally, it serves as a key component in solid oxide fuel cells (SOFCs) due to its mixed ionic and electronic conductivity, enhancing oxygen ion transport and improving cell efficiency at lower operating temperatures. It is also employed in oxygen sensors and membranes for high-temperature oxygen separation. This material shows promise in catalytic applications, especially for oxidation reactions and environmental remediation processes. Its unique redox properties make it suitable for advanced materials in energy storage and conversion technologies, as well as in high-temperature ceramics and sensors requiring chemical stability and thermal durability.