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 catalysts, especially in environments requiring oxygen storage and release. The material is employed in ceramic capacitors and gas sensors owing to its mixed-valence nature, which enhances electrical conductivity and responsiveness to environmental changes. It also finds use in phosphors for display technologies, where it contributes to green luminescence when activated, improving color balance and efficiency in lighting and imaging systems. Additionally, it is explored in fuel cell technologies as a dopant to improve the performance of electrolytes and electrodes under high-temperature conditions.