Editing Strontium (section)

==Applications==
[[File:Monitor.arp.jpg|thumb|Most of the world's production of strontium used to be consumed in the production of cathode-ray tube (CRT) displays. The glass contained strontium and barium oxide to block X-rays.]]

Consuming 75% of production, the primary use for strontium was in glass for colour television [[cathode-ray tube]]s,<ref name="Ullmann" /> where it prevented [[X-ray]] emission.<ref>{{cite web |title = Cathode Ray Tube Glass-To-Glass Recycling |publisher = ICF Incorporated, USEP Agency |url = http://yosemite.epa.gov/ee/epa/riafile.nsf/419e576a3df1421685256470007e3141/5a52093c460136ac85256cf6008062d0/$FILE/S99-23.pdf |archive-url = https://web.archive.org/web/20081219162330/http://yosemite.epa.gov/ee/epa/riafile.nsf/419e576a3df1421685256470007e3141/5a52093c460136ac85256cf6008062d0/$FILE/S99-23.pdf |archive-date = 19 December 2008 | access-date = 7 January 2012}}</ref><ref>{{cite web |publisher = United States Geological Survey |access-date = 14 October 2008 |title = Mineral Yearbook 2007: Strontium |first = Joyce A. |last = Ober |author2 = Polyak, Désirée E. |url = http://minerals.usgs.gov/minerals/pubs/commodity/strontium/myb1-2007-stron.pdf |archive-date = 20 September 2008 |archive-url = https://web.archive.org/web/20080920070543/http://minerals.usgs.gov/minerals/pubs/commodity/strontium/myb1-2007-stron.pdf |url-status = dead }}</ref> This application for strontium has been declining because CRTs are being replaced by other display methods. This decline has a significant influence on the mining and refining of strontium.<ref name="usgs10" /> All parts of the CRT must absorb X-rays. In the neck and the funnel of the tube, lead glass is used for this purpose, but this type of glass shows a browning effect due to the interaction of the X-rays with the glass. Therefore, the front panel is made from a different glass mixture with strontium and barium to absorb the X-rays. The average values for the glass mixture determined for a recycling study in 2005 is 8.5% [[strontium oxide]] and 10% [[barium oxide]].<ref>{{cite journal |doi = 10.1016/j.wasman.2005.11.017 |pmid = 16427267 |date = 2006 |last1 = Méar |first1 = F. |last2 = Yot |first2 = P. |last3 = Cambon |first3 = M. |last4 = Ribes |first4 = M. |title = The characterization of waste cathode-ray tube glass |volume = 26 |issue = 12 |pages = 1468–76 |journal = Waste Management |bibcode = 2006WaMan..26.1468M }}</ref>

Because strontium is so similar to calcium, it is incorporated in the bone. All four stable isotopes are incorporated, in roughly the same proportions they are found in nature. However, the actual distribution of the isotopes tends to vary greatly from one geographical location to another. Thus, analyzing the bone of an individual can help determine the region it came from.<ref name="PriceSchoeninger1985">{{cite journal|last1=Price|first1=T. Douglas|last2=Schoeninger|first2=Margaret J.|author2-link=Margaret Schoeninger|last3=Armelagos|first3=George J.|title=Bone chemistry and past behavior: an overview|journal=Journal of Human Evolution|volume=14|issue=5|year=1985|pages=419–47|doi=10.1016/S0047-2484(85)80022-1|bibcode=1985JHumE..14..419P }}</ref><ref name="SteadmanBrudevold1958">{{cite journal|last1=Steadman|first1=Luville T.|last2=Brudevold|first2=Finn|last3=Smith|first3=Frank A.|title=Distribution of strontium in teeth from different geographic areas|journal=The Journal of the American Dental Association|volume=57|issue=3|year=1958|pages=340–44|doi=10.14219/jada.archive.1958.0161|pmid=13575071}}</ref> This approach helps to identify the ancient migration patterns and the origin of commingled human remains in battlefield burial sites.<ref name="SchweissingGrupe2003">{{cite journal|last1=Schweissing|first1=Matthew Mike|last2=Grupe|first2=Gisela|title=Stable strontium isotopes in human teeth and bone: a key to migration events of the late Roman period in Bavaria|journal=Journal of Archaeological Science|volume=30|issue=11|year=2003|pages=1373–83|doi=10.1016/S0305-4403(03)00025-6|bibcode=2003JArSc..30.1373S }}</ref>

<sup>87</sup>Sr/<sup>86</sup>Sr ratios are commonly used to determine the likely provenance areas of sediment in natural systems, especially in [[Marine environments|marine]] and [[River|fluvial]] environments. Dasch (1969) showed that surface sediments of Atlantic displayed <sup>87</sup>Sr/<sup>86</sup>Sr ratios that could be regarded as bulk averages of the <sup>87</sup>Sr/<sup>86</sup>Sr ratios of geological terrains from adjacent landmasses.<ref name="Dasch">{{cite journal |journal=Geochimica et Cosmochimica Acta |volume=33 |issue=12 |pages=1521–52 |date=1969 |last=Dasch |first = J.| title=Strontium isotopes in weathering profiles, deep-sea sediments, and sedimentary rocks| doi = 10.1016/0016-7037(69)90153-7 |bibcode = 1969GeCoA..33.1521D }}</ref> A good example of a fluvial-marine system to which Sr isotope provenance studies have been successfully employed is the River Nile-Mediterranean system.<ref name="Krom1999">{{cite journal |journal=Marine Geology |volume=155 |issue=3–4 |pages=319–30 |date=1999 |last1= Krom |first1 = M. D. |last2= Cliff |first2 =R.| last3=Eijsink |first3 = L. M. |last4= Herut |first4 =B. |title=The characterisation of Saharan dusts and Nile particulate matter in surface sediments from the Levantine basin using Sr isotopes |doi = 10.1016/S0025-3227(98)00130-3 |last5=Chester |first5=R. |bibcode=1999MGeol.155..319K }}</ref><!--.<ref name=Krom2002>{{cite journal |journal=Geology |volume=30 |issue=1 |pages=71–74 |date=2002 |first1 = Michael D. |last1=Krom |first2 = J. Daniel |last2=Stanley |first3 = Robert A. |last3=Cliff |first4 = Jamie C. |last4= Woodward |title=Nile River sediment fluctuations over the past 7000 yr and their key role in sapropel development |doi = 10.1130/0091-7613(2002)030<0071:NRSFOT>2.0.CO;2 |year=2002 |bibcode = 2002Geo....30...71K }}</ref><ref name=Talbot>{{cite journal |journal=Geology |volume=28 |issue=4 |pages=343–46| date=2000 |author=Talbot, M. R. et al.| title=Strontium isotope evidence for late Pleistocene reestablishment of an integrated Nile drainage network |doi = 10.1130/0091-7613(2000)28<343:SIEFLP>2.0.CO;2 |year=2000 |bibcode = 2000Geo....28..343T }}</ref>--> Due to the differing ages of the rocks that constitute the majority of the [[Blue Nile|Blue]] and [[White Nile]], [[catchment area]]s of the changing provenance of sediment reaching the [[River Nile Delta]] and East Mediterranean Sea can be discerned through strontium isotopic studies. Such changes are climatically controlled in the [[Late Quaternary]].<ref name="Krom1999" />

More recently, <sup>87</sup>Sr/<sup>86</sup>Sr ratios have also been used to determine the source of ancient archaeological materials such as timbers and corn in [[Chaca Canyon, New Mexico|Chaco Canyon, New Mexico]].<ref name="Benson">{{cite journal |journal=Proceedings of the National Academy of Sciences |volume=100 |issue=22 |pages=13111–15 |date=2003 |author=Benson, L. |author2=Cordell, L. |author3=Vincent, K. |author4=Taylor, H. |author5=Stein, J. |author6=Farmer, G. |author7=Kiyoto, F. |name-list-style=amp |pmid=14563925 |title= Ancient maize from Chacoan great houses: where was it grown?|pmc=240753 |doi = 10.1073/pnas.2135068100 |bibcode = 2003PNAS..10013111B |doi-access=free }}</ref><ref name="English">{{cite journal |journal=Proc Natl Acad Sci USA |volume=98 |issue=21 |pages=11891–96 |date=October 2001 |author=English NB |author2=Betancourt JL |author3=Dean JS |author4=Quade J. |title=Strontium isotopes reveal distant sources of architectural timber in Chaco Canyon, New Mexico|pmid=11572943 |doi = 10.1073/pnas.211305498 |pmc=59738 |bibcode = 2001PNAS...9811891E |doi-access=free }}</ref> <sup>87</sup>Sr/<sup>86</sup>Sr ratios in teeth may also be used to [[Animal migration tracking|track animal migrations]].<ref name="Barnett-Johnson">{{cite journal |journal=Canadian Journal of Fisheries and Aquatic Sciences |volume=64 |issue=12 |pages=1683–92 |date=2007 |author=Barnett-Johnson, Rachel |title=Identifying the contribution of wild and hatchery Chinook salmon (Oncorhynchus tshawytscha) to the ocean fishery using otolith microstructure as natural tags |doi = 10.1139/F07-129 |last2=Grimes |first2=Churchill B. |last3=Royer |first3=Chantell F. |last4=Donohoe |first4=Christopher J. |bibcode=2007CJFAS..64.1683B |s2cid=54885632 |url=https://zenodo.org/record/1235897 }}</ref><ref name="Porder">{{cite journal |journal=Paleobiology |volume=29 |issue=2 |pages=197–204 |author=Porder, S. |author2=Paytan, A. |author3=E.A. Hadly |name-list-style=amp |title=Mapping the origin of faunal assemblages using strontium isotopes |doi = 10.1666/0094-8373(2003)029<0197:MTOOFA>2.0.CO;2 |year=2003 |s2cid=44206756 }}</ref>

[[Strontium aluminate]] is frequently used in [[Phosphorescence|glow in the dark]] toys, as it is chemically and biologically inert.<ref>{{cite journal |last1=Van der Heggen |first1=David |title=Persistent Luminescence in Strontium Aluminate: A Roadmap to a Brighter Future |journal=Advanced Functional Materials |date=October 2022 |volume=32 |issue=52 |doi=10.1002/adfm.202208809 |url=https://onlinelibrary.wiley.com/doi/10.1002/adfm.202208809 |access-date=21 April 2023|hdl=1854/LU-01GJ1338HX6QQBT438E4QW442N |s2cid=253347258 |hdl-access=free }}</ref>

[[File:Ignis Brunensis 2010-05-22 (5).jpg|alt=red fireworks|thumb|upright|Strontium salts are added to fireworks in order to create red colors.]]

[[Strontium carbonate]] and other strontium [[Salt (chemistry)|salts]] are added to fireworks to give a deep red colour.<ref>{{cite web |url=http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm |title=Chemistry of Firework Colors – How Fireworks Are Colored |publisher=Chemistry.about.com |date=10 April 2012 |access-date=14 April 2012 |archive-date=13 May 2008 |archive-url=https://web.archive.org/web/20080513202402/http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm |url-status=dead }}</ref> This same effect identifies strontium [[cations]] in the [[flame test]]. Fireworks consume about 5% of the world's production.<ref name="Ullmann">MacMillan, J. Paul; Park, Jai Won; Gerstenberg, Rolf; Wagner, Heinz; Köhler, Karl and Wallbrecht, Peter (2002) "Strontium and Strontium Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a25_321}}.</ref> Strontium carbonate is used in the manufacturing of hard [[ferrite (magnet)|ferrite]] magnets.<ref>{{cite web |url=http://www.arnoldmagnetics.com/Ferrite.aspx |title=Ferrite Permanent Magnets |author=<!--Staff writer(s); no by-line.--> |publisher=Arnold Magnetic Technologies |access-date=18 January 2014 |url-status=dead |archive-url=https://web.archive.org/web/20120514152507/http://www.arnoldmagnetics.com/Ferrite.aspx |archive-date=14 May 2012 |df=dmy-all }}</ref><ref>{{cite web |url=http://www.cpc-us.com/products/barium-carbonate.html |title=Barium Carbonate |author=<!--Staff writer(s); no by-line.--> |publisher=Chemical Products Corporation |access-date=18 January 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141006124351/http://www.cpc-us.com/products/barium-carbonate.html |archive-date=6 October 2014 |df=dmy-all }}</ref>

[[Strontium chloride]] is sometimes used in toothpastes for sensitive teeth. One popular brand includes 10% total strontium chloride hexahydrate by weight.<ref>{{cite book | url = https://books.google.com/books?id=cwom9OTMmGYC&pg=PA885 | page = 885 | title = Textbook of Oral Medicine | isbn = 978-81-8061-431-6 | author1 = Ghom | date = 1 December 2005 | publisher = Jaypee Brothers, Medical Publishers }}{{Dead link|date=August 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Small amounts are used in the refining of zinc to remove small amounts of lead impurities.<ref name="CRC" /> The metal itself has a limited use as a [[getter]], to remove unwanted gases in vacuums by reacting with them, although barium may also be used for this purpose.<ref name="Greenwood111">Greenwood and Earnshaw, p. 111</ref>

The ultra-narrow optical transition between the [Kr]5s<sub>2</sub> <sup>1</sup>S<sub>0</sub> electronic [[ground state]] and the [[Metastability|metastable]] [Kr]5s5p <sup>3</sup>P<sub>0</sub> excited state of <sup>87</sup>Sr is one of the leading candidates for the future re-definition of the [[second]] in terms of an optical transition as opposed to the current definition derived from a microwave transition between different [[Hyperfine structure|hyperfine]] ground states of [[Caesium|<sup>133</sup>Cs.]]<ref>{{Cite web|url=https://www.science.org/content/article/better-atomic-clocks-scientists-prepare-redefine-second|title=With better atomic clocks, scientists prepare to redefine the second|last1=Cartlidge|first1=Edwin|date=2018-02-28|website=Science {{!}} AAAS|language=en|access-date=2019-02-10}}</ref> Current optical [[atomic clock]]s operating on this transition already surpass the precision and accuracy of the current definition of the second.<ref>{{Cite web |title=Recommended values of standard frequencies - BIPM |url=https://www.bipm.org/en/publications/mises-en-pratique/standard-frequencies?version=1.4&t=1637238077933&download=true |access-date=2023-05-21 |website=www.bipm.org}}</ref>

===Radioactive strontium===
[[File:Soviet RTG.jpg|thumb|RTGs from Soviet-era lighthouses]]

[[strontium-89|<sup>89</sup>Sr]] is the active ingredient in [[Metastron]],<ref>{{cite web |title=FDA ANDA Generic Drug Approvals |url=https://www.fda.gov/Drugs/DevelopmentApprovalProcess/HowDrugsareDevelopedandApproved/DrugandBiologicApprovalReports/ANDAGenericDrugApprovals/UCM064272 |publisher=[[Food and Drug Administration]]}}</ref> a [[radiopharmaceutical]] used for bone pain secondary to [[metastatic]] [[bone cancer]]. The strontium is processed like calcium by the body, preferentially incorporating it into bone at sites of increased [[osteogenesis]]. This localization focuses the radiation exposure on the cancerous lesion.<ref name="BaumanCharette2005" />

[[strontium-90|<sup>90</sup>Sr]] has been used as a power source for [[radioisotope thermoelectric generator]]s (RTGs). <sup>90</sup>Sr produces approximately 0.93 watts of heat per gram (it is lower for the form of <sup>90</sup>Sr used in RTGs, which is [[strontium fluoride]]).<ref>{{cite web |url=http://www.qrg.northwestern.edu/projects/vss/docs/Power/3-what-are-the-fuels-for-rtgs.html |title=What are the fuels for radioisotope thermoelectric generators?|work=qrg.northwestern.edu}}</ref><!--Search for a better source--> However, <sup>90</sup>Sr has one third the lifetime and a lower density than [[plutonium-238|<sup>238</sup>Pu]], another RTG fuel. The main advantage of <sup>90</sup>Sr is that it is significantly cheaper than <sup>238</sup>Pu and is found in [[nuclear waste]]. The latter must be prepared by irradiating <sup>237</sup>Np with neutrons then separating the modest amounts of  <sup>238</sup>Pu. The principal disadvantage of <sup>90</sup>Sr is the high energy beta particles produce [[Bremsstrahlung]] as they encounter nuclei of other nearby heavy atoms such as adjacent strontium. This is mostly in the range of X-rays. Thus strong beta emitters also emit significant secondary X-rays in most cases. This requires significant shielding measures which complicates the design of RTGs using <sup>90</sup>Sr. The [[Soviet Union]] deployed nearly 1000 of these RTGs on its northern coast as a power source for lighthouses and meteorology stations.<ref>{{cite book |page = 459 |url = https://books.google.com/books?id=8WOza_y3IkQC&pg=PA459 |title = Nuclear safeguards, security and nonproliferation: achieving security with technology and policy |isbn = 978-0-7506-8673-0 |author1 = Doyle, James |date = 30 June 2008| publisher=Elsevier }}</ref><ref name="O'BrienAmbrosi2008">{{cite journal|last1=O'Brien|first1=R. C.|last2=Ambrosi|first2=R. M.|last3=Bannister|first3=N. P.|last4=Howe|first4=S. D.|last5=Atkinson|first5=H. V.|title=Safe radioisotope thermoelectric generators and heat sources for space applications|journal=Journal of Nuclear Materials|volume=377|issue=3|year=2008|pages=506–21|doi=10.1016/j.jnucmat.2008.04.009|bibcode=2008JNuM..377..506O}}</ref>