Pm61
Promethium
The radioactive ghost of the lanthanides — no stable isotope, no mine, no market.
Promethium is the only rare earth with no stable isotope: every atom of it is radioactive, and virtually none survives in nature. The promethium used in research and niche devices is synthesized in nuclear reactors from uranium fission products. Its historical application was luminous paint and compact nuclear batteries for guided missiles and pacemakers; today its use is largely confined to research, thickness gauges, and specialized beta radiation sources. It is included here for completeness of the lanthanide series.
Key Applications
- Nuclear (betavoltaic) batteries for space and defense
- Luminous paint (historical) and beta radiation sources
- Thickness gauges for industrial films
- Scientific research into lanthanide chemistry
Key Facts
- Atomic number
- 61
- Stable isotopes
- None — fully radioactive
- Supply
- Reactor-synthesized only
- Commercial market
- Negligible
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