Editing Promethium (section)

==Applications==
[[File:Pm,61.jpg|thumb|right|upright=0.9|[[Promethium(III) chloride]] being used as a light source for signals in a heat button]]
Only promethium-147 has uses outside laboratories.{{sfn|Emsley|2011|p=428}} It is obtained as the oxide or chloride,{{sfn|Lavrukhina|Pozdnyakov|1966|p=118}} in milligram quantities.{{sfn|Emsley|2011|p=428}} This isotope has a relatively long half-life, does not emit [[gamma rays]], and its radiation has a relatively small penetration depth in matter.{{sfn|Lavrukhina|Pozdnyakov|1966|p=118}}

Some signal lights use a [[luminous paint]] containing a [[phosphor]] that absorbs the beta radiation emitted by promethium-147 and emits light.<ref name="CRCel" />{{sfn|Emsley|2011|p=428}} This isotope does not cause aging of the phosphor, as alpha emitters do,{{sfn|Lavrukhina|Pozdnyakov|1966|p=118}} and therefore the light emission is stable for a few years.{{sfn|Lavrukhina|Pozdnyakov|1966|p=118}} Originally, [[radium]]-226 was used for the purpose, but it was later replaced by promethium-147 and [[tritium]] (hydrogen-3).<ref>{{Cite book|title = Man-made and natural radioactivity in environmental pollution and radiochronology|year = 2004|page = 78|isbn = 978-1-4020-1860-2|last1 = Tykva|first1 = Richard
|last2 = Berg|first2 = Dieter|publisher=Springer}}</ref> Promethium may be favored over tritium for [[nuclear safety]].<ref name="Deeter1993">{{cite book
|title = Disease and the Environment|year = 1993|author = Deeter, David P.|page = 187|publisher = Government Printing Office}}</ref>

In [[atomic battery|atomic batteries]], the beta particles emitted by promethium-147 are converted into electric current by sandwiching a small promethium source between two semiconductor plates. These batteries have a useful lifetime of about five years.<ref name="brit" /><ref name="CRCel" />{{sfn|Emsley|2011|p=428}} The first promethium-based battery was assembled in 1964 and generated "a few milliwatts of power from a volume of about 2 cubic inches, including shielding".<ref>{{cite journal|doi=10.1109/T-ED.1964.15271|title=Construction of a promethium-147 atomic battery|year=1964|last1=Flicker|first1=H.|last2=Loferski|first2=J. J.|last3=Elleman|first3=T. S.|journal=IEEE Transactions on Electron Devices|volume=11|issue=1|pages=2|bibcode=1964ITED...11....2F}}</ref>

Promethium is also used to measure the thickness of materials by measuring the amount of radiation from a promethium source that passes through the sample.<ref name="CRCel" />{{sfn|Emsley|2011|p=429}}<ref>{{cite book |title=The Terrorist Effect – Weapons of Mass Disruption: The Danger of Nuclear Terrorism |last1=Jones |first1=James William |last2=Haygood |first2=John R. |year=2011 |publisher=iUniverse |isbn=978-1-4620-3932-6 |page=180 |url=https://books.google.com/books?id=YwE0W6LsxygC&pg=PA180|access-date=January 13, 2012}}</ref> It has possible future uses in portable X-ray sources, and as auxiliary heat or power sources for space probes and satellites<ref name="Stwertka2002">{{cite book|title = A guide to the elements|year = 2002|publisher = Oxford University Press|author = Stwertka, Albert|page = 154|isbn = 978-0-19-515026-1}}</ref> (although the alpha emitter [[plutonium-238]] has become standard for most space-exploration-related uses).<ref name="Radioisotope2009">{{cite book|title = Radioisotope power systems: an imperative for maintaining U.S. leadership in space exploration|year = 2009|author = Radioisotope Power Systems Committee, National Research Council U.S.|page = 8|isbn = 978-0-309-13857-4|publisher = National Academies Press}}</ref>

Promethium-147 is also used, albeit in very small quantities (less than 330nCi), in some [[Philips]] CFL (Compact Fluorescent Lamp) glow switches in the PLC 22W/28W 15mm CFL range.<ref>https://www.msdsdigital.com/system/files/PHILIPS-CFL-15MM.pdf MSDS for the Philips CFL lamps containing Pm-147.</ref>