Terbium
Element 65 · Lanthanide
Terbium is a soft, silvery metal that is stable in air and usually +3 in compounds, though it can reach +4. Its green fluorescence is its signature: terbium phosphors provide the green component in trichromatic fluorescent lamps and older color displays.
Alloyed with iron and dysprosium as Terfenol-D, terbium forms a magnetostrictive material that stretches in magnetic fields — used in sonar systems, precision actuators, and vibration sensors. It is one of four elements named after the Swedish village of Ytterby.
Key facts
| Atomic number | 65 |
|---|---|
| Atomic weight | 158.93 |
| Category | Lanthanide |
| Group / Period | — / 6 |
| Block | f |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f9 |
| Common oxidation states | +3, +4 |
| State at STP | Solid |
| Electronegativity | 1.10 |
| Density | 8.23 g/cm³ |
| Melting point | 1356 °C |
| Boiling point | 3230 °C |
Occurrence
Terbium occurs in monazite, xenotime, and euxenite, and is among the scarcer lanthanides, usually recovered as a byproduct of other rare-earth mining.
Applications
Green phosphors in fluorescent lamps
Terfenol-D magnetostrictive alloys
Sonar and precision actuators
Solid-state electronic devices
Common compounds
- terbium oxide
- terbium chloride
Terbium is one of four elements named after the Swedish village of Ytterby — along with yttrium, erbium, and ytterbium.
Data source: IUPAC standard atomic weights 2021