Terbium is a chemical element with symbol Tb and atomic number 65. It is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.
Three reasons Terbium stands out
- 1
Used as green phosphor in TVs.
- 2
It is used in an alloy that physically changes shape when placed in a magnetic field, enabling precision actuators and sonar.
- 3
Its green fluorescence is used in the security inks printed on banknotes to prevent counterfeiting.
Green light from a difficult-to-separate metal
Terbium compounds produce vivid green emission in displays, lamps, and anti-counterfeiting marks. The element also joins alloys that change shape in a magnetic field, converting magnetism into precise motion. Like its lanthanide neighbors, terbium was difficult to identify because their chemical behavior is so similar.