Terbium
Terbium is a silvery, fairly rare lanthanide first identified in 1843, one of several elements traced back to a single mineral quarry near the Swedish village of Ytterby. It shows up wherever a bright green glow is needed, from energy-efficient lighting to specialized sensors.
- Group · Period
- — · 6
- At room temp
- solid
- Melts at
- 1629 K
- Density
- 8.23 g/cm³
- Discovered
- 1843
Uses
Terbium’s most familiar use is as a green-emitting phosphor. Terbium-doped compounds glow a bright, efficient green under electrical or ultraviolet excitation, and for decades that made them a standard ingredient in fluorescent lighting tubes and in the phosphor coatings of older television and computer displays. It’s also combined with dysprosium and iron to make Terfenol-D, an alloy that changes shape slightly when placed in a magnetic field — a property called magnetostriction that’s used in sonar transducers, precision actuators, and some acoustic devices.
Because it’s one of the rarer and more expensive lanthanides, terbium tends to be used in relatively small quantities, often blended with cheaper rare earths to fine-tune the color or magnetic properties of a material rather than as a bulk component on its own.
History
Terbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander, who was busy re-examining a rare-earth mineral called yttria that had originally been found near the village of Ytterby, Sweden. Mosander showed that yttria wasn’t a single substance but a mixture, and in teasing it apart he identified both terbium and erbium as distinct components. Like the mineral’s other namesakes, terbium was named after Ytterby itself, the small village whose quarry ended up lending its name to four separate elements.
Fun facts
- Terbium is one of four elements named after the tiny Swedish village of Ytterby, alongside yttrium, erbium, and ytterbium.
- Terbium-doped phosphors produce the green light used in many fluorescent lamps and older display screens.
- Combined with dysprosium and iron, terbium forms Terfenol-D, an alloy that changes shape in a magnetic field and is used in sonar and precision actuators.
Frequently asked questions
What is terbium actually used for?
Its main job is as a green phosphor — terbium compounds glow a bright, efficient green when excited by electricity or UV light, which is why they've been used in fluorescent lighting and in older television and display screens. Terbium is also a key ingredient in Terfenol-D, a magnetostrictive alloy that changes shape slightly in a magnetic field, useful for sonar transducers and precise actuators.
Why are yttrium, terbium, erbium, and ytterbium all named after the same village?
All four were discovered in ore dug from a single quarry near Ytterby, Sweden, that turned out to contain a remarkable mix of rare-earth elements. As chemists slowly separated the mixture into distinct elements over the 19th century, they kept honoring the source by naming new discoveries after the village itself.
Is terbium dangerous or hard to handle?
Terbium metal isn't especially hazardous under normal handling, though like other reactive metals it should be kept away from open flame and tarnishes slowly in air. The bigger practical challenge with terbium is its scarcity and the difficulty of separating it cleanly from other lanthanides, not any special toxicity.
Compounds
2 notable compounds containing Tb
- Tb4O7oxide
Terbium oxide
A dark brown, mixed-valence oxide containing both Tb3+ and Tb4+ ions, making it the most thermodynamically stable oxide of terbium under normal conditions.
Used for: Precursor for terbium-activated green phosphors used in lighting and displays
- TbCl3halide
Terbium(III) chloride
A white to pale-tan, hygroscopic terbium salt used as a common laboratory starting material for other terbium(III) compounds.
Used for: Precursor for synthesizing terbium phosphor and magnetic compounds
Isotopes
38 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Tb-159 stable | 100% | Stable | — | -69,532.58 keV | 8,188.8 keV | — |
Show all 38 isotopes
| Tb-135 | — | 0.94 ms | Proton emission (100%), Electron capture / beta-plus decay | -33,053 keV | 7,939 keV | 4.85 × 10-13 eV |
| Tb-138 | — | 200 ns | Electron capture / beta-plus decay (100%) | -43,600 keV | 8,019 keV | 2.28 × 10-9 eV |
| Tb-139 | — | 1.6 s | Electron capture / beta-plus decay (0%), ECP, Proton emission | -48,130 keV | 8,052 keV | 2.85 × 10-16 eV |
| Tb-140 | — | 2.29 s | Electron capture / beta-plus decay (100%), ECP (0.26%) | -50,482.28 keV | 8,068.67 keV | 1.99 × 10-16 eV |
| Tb-141 | — | 3.5 s | Electron capture / beta-plus decay (100%) | -54,540.84 keV | 8,097.48 keV | 1.30 × 10-16 eV |
| Tb-142 | — | 597 ms | Electron capture / beta-plus decay (100%), Beta-plus, proton emission (0.0022%) | -56,559.52 keV | 8,111.51 keV | 7.64 × 10-16 eV |
| Tb-143 | — | 12 s | Electron capture / beta-plus decay (100%) | -60,419.19 keV | 8,138.22 keV | 3.80 × 10-17 eV |
| Tb-144 | — | 1 s | Electron capture / beta-plus decay (100%) | -62,368.19 keV | 8,151.29 keV | 4.56 × 10-16 eV |
| Tb-145 | — | — | Unknown | -66,399.69 keV | 8,178.54 keV | — |
| Tb-146 | — | 8 s | Electron capture / beta-plus decay (100%) | -67,763.64 keV | 8,187.15 keV | 5.70 × 10-17 eV |
| Tb-147 | — | 1.64 h | Electron capture / beta-plus decay (100%) | -70,742.67 keV | 8,206.63 keV | 7.73 × 10-20 eV |
| Tb-148 | — | 60 m | Electron capture / beta-plus decay (100%) | -70,536.95 keV | 8,204.32 keV | 1.27 × 10-19 eV |
| Tb-149 | — | 4.12 h | Electron capture / beta-plus decay (83.3%), Alpha decay (16.7%) | -71,488.64 keV | 8,209.82 keV | 3.08 × 10-20 eV |
| Tb-150 | — | 3.48 h | Electron capture / beta-plus decay (100%), Alpha decay (0.05%) | -71,105.79 keV | 8,206.34 keV | 3.64 × 10-20 eV |
| Tb-151 | — | 17.609 h | Electron capture / beta-plus decay (99.9905%), Alpha decay (0.0095%) | -71,623.54 keV | 8,208.87 keV | 7.20 × 10-21 eV |
| Tb-152 | — | 17.5 h | Electron capture / beta-plus decay (100%), Alpha decay (7e-7%) | -70,717.3 keV | 8,202.01 keV | 7.24 × 10-21 eV |
| Tb-153 | — | 2.34 d | Electron capture / beta-plus decay (100%) | -71,313.61 keV | 8,205.05 keV | 2.26 × 10-21 eV |
| Tb-154 | — | 21.5 h | Electron capture / beta-plus decay (100%), Beta-minus decay (0.1%) | -70,156.71 keV | 8,196.67 keV | 5.89 × 10-21 eV |
| Tb-155 | — | 5.32 d | Electron capture (100%) | -71,250.44 keV | 8,202.92 keV | 9.93 × 10-22 eV |
| Tb-156 | — | 5.35 d | Electron capture / beta-plus decay (100%) | -70,091.01 keV | 8,194.64 keV | 9.87 × 10-22 eV |
| Tb-157 | — | 71 Y | Electron capture (100%) | -70,763.85 keV | 8,198.14 keV | 2.04 × 10-25 eV |
| Tb-158 | — | 180 Y | Electron capture / beta-plus decay (83.4%), Beta-minus decay (16.6%) | -69,470.88 keV | 8,189.16 keV | 8.03 × 10-26 eV |
| Tb-160 | — | 72.3 d | Beta-minus decay (100%) | -67,836.47 keV | 8,177.47 keV | 7.30 × 10-23 eV |
| Tb-161 | — | 6.89 d | Beta-minus decay (100%) | -67,461.78 keV | 8,174.48 keV | 7.66 × 10-22 eV |
| Tb-162 | — | 7.60 m | Beta-minus decay (100%) | -65,879.55 keV | 8,164.08 keV | 1.00 × 10-18 eV |
| Tb-163 | — | 19.5 m | Beta-minus decay (100%) | -64,595.75 keV | 8,155.63 keV | 3.90 × 10-19 eV |
| Tb-164 | — | 3.0 m | Beta-minus decay (100%) | -62,104.98 keV | 8,139.93 keV | 2.53 × 10-18 eV |
| Tb-165 | — | 2.11 m | Beta-minus decay (100%) | -60,588.85 keV | 8,130.33 keV | 3.60 × 10-18 eV |
| Tb-166 | — | 25.1 s | Beta-minus decay (100%) | -57,808.78 keV | 8,113.22 keV | 1.82 × 10-17 eV |
| Tb-167 | — | 19.4 s | Beta-minus decay (100%) | -55,883.08 keV | 8,101.44 keV | 2.35 × 10-17 eV |
| Tb-168 | — | 8.2 s | Beta-minus decay (100%) | -52,781.18 keV | 8,082.8 keV | 5.56 × 10-17 eV |
| Tb-169 | — | 5.1 s | Beta-minus decay (100%), Beta-minus, neutron emission | -50,480 keV | 8,069 keV | 8.95 × 10-17 eV |
| Tb-170 | — | 0.96 s | Beta-minus decay (100%), Beta-minus, neutron emission | -46,710 keV | 8,047 keV | 4.75 × 10-16 eV |
| Tb-171 | — | 1.24 s | Beta-minus decay (100%), Beta-minus, neutron emission | -43,770 keV | 8,030 keV | 3.68 × 10-16 eV |
| Tb-172 | — | 0.76 s | Beta-minus decay (100%), Beta-minus, neutron emission | -39,690 keV | 8,006 keV | 6.00 × 10-16 eV |
| Tb-173 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | -36,510 keV | 7,988 keV | — |
| Tb-174 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | -31,970 keV | 7,963 keV | — |