Terbium Hydroxide 99.99% also called Terbium Hydrate, has important role as an activator for green phosphors used in colour TV tubes, is also used in special lasers and as a dopant in solid-state devices. Terbium 'green' phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent Europium blue phosphors and trivalent Europium red phosphors to provide the 'trichromatic' lighting technology which is by far the largest consumer of the world's Terbium supply. Trichromatic lighting provides much higher light output for a given amount of electrical energy than does incandescent lighting. It is also used in alloys and in the production of electronic devices. The other main application is used for manufacturing optical glass.