Terbium is primarily used in phosphors, particularly in fluorescent lamps and as the high intensity green emitter. In combination with Europium blue and red phosphors, they create trichromatic lighting effect which is brighter than conventional fluorescent materials.
Terbium responds efficiently to x-ray excitation as well, therefore, it has been used as an x-ray phosphor.
In combination with neodymium, it can form the most heat resistant super magnets. Terbium alloys, such as TbFeCo, are also used in magneto-optic recording films.
Terbium is also used in alloys and in the production of electronic devices.
As a component of Terfenol-D, a material that can be used as actuators and transducers in naval sonar systems, sensors, in the SoundBug device and other magnetomechanical devices.