Editing Actinium (section)

==Occurrence and synthesis==
[[File:Uraninite-39029.jpg|upright=0.70|thumb|[[Uraninite]] ores have elevated concentrations of actinium.]]
Actinium is found only in traces in [[uranium]] ores&nbsp;– one tonne of uranium in ore contains about 0.2 milligrams of <sup>227</sup>Ac<ref name="Hagemann1950">{{cite journal |doi=10.1021/ja01158a033 |last1=Hagemann |date=1950 |first1=French |pages=768–771 |volume=72 |journal=Journal of the American Chemical Society |title=The Isolation of Actinium |issue=2|bibcode=1950JAChS..72..768H }}</ref><ref name="g946">{{Greenwood&Earnshaw2nd|page=946}}</ref> – and in [[thorium]] ores, which contain about 5 nanograms of <sup>228</sup>Ac per one tonne of thorium. The actinium [[isotope]] <sup>227</sup>Ac is a transient member of the [[Decay chain#Actinium series|uranium-actinium series]] [[decay chain]], which begins with the parent isotope [[Uranium-235|<sup>235</sup>U]] (or [[Plutonium-239|<sup>239</sup>Pu]]) and ends with the stable lead isotope [[lead-207|<sup>207</sup>Pb]]. The isotope <sup>228</sup>Ac is a transient member of the [[thorium series]] decay chain, which begins with the parent isotope [[Thorium-232|<sup>232</sup>Th]] and ends with the stable lead isotope [[lead-208|<sup>208</sup>Pb]]. Another actinium isotope (<sup>225</sup>Ac) is transiently present in the [[neptunium series]] [[decay chain]], beginning with [[Neptunium-237|<sup>237</sup>Np]] (or [[Uranium-233|<sup>233</sup>U]]) and ending with thallium ([[thallium-205|<sup>205</sup>Tl]]) and near-stable bismuth ([[bismuth-209|<sup>209</sup>Bi]]); even though all [[primordial nuclide|primordial]] <sup>237</sup>Np has decayed away, it is continuously produced by neutron knock-out reactions on natural <sup>238</sup>U.

The low natural concentration, and the close similarity of physical and chemical properties to those of lanthanum and other lanthanides, which are always abundant in actinium-bearing ores, render separation of actinium from the ore impractical. The most concentrated actinium sample prepared from raw material consisted of 7 micrograms of <sup>227</sup>Ac in less than 0.1 milligrams of La<sub>2</sub>O<sub>3</sub>, and complete separation was never achieved.<ref name=KirbyReview>{{Cite book |last1=Kirby |first1=H. W. |url=http://link.springer.com/10.1007/978-94-007-0211-0_2 |title=Actinium |last2=Morss |first2=Lester R. |date=2010 |publisher=Springer Netherlands |isbn=978-94-007-0210-3 |editor-last=Morss |editor-first=Lester R. |location=Dordrecht |pages=18–51 |language=en |doi=10.1007/978-94-007-0211-0_2 |editor-last2=Edelstein |editor-first2=Norman M. |editor-last3=Fuger |editor-first3=Jean}}</ref> Instead, actinium is prepared, in milligram amounts, by the neutron irradiation of {{chem2|^{226}Ra|link=Radium-226}} in a [[nuclear reactor]].<ref name="g946" /><ref>{{cite book |author=Emeleus, H. J. |title=Advances in inorganic chemistry and radiochemistry |url=https://books.google.com/books?id=K5_LSQqeZ_IC&pg=PA16 |date= 1987 |publisher=Academic Press |isbn=978-0-12-023631-2 |pages=16–}}</ref>
:<chem>^{226}_{88}Ra + ^{1}_{0}n -> ^{227}_{88}Ra ->[\beta^-][42.2 \ \ce{min}] ^{227}_{89}Ac</chem>
The reaction yield is about 2% of the radium weight. <sup>227</sup>Ac can further capture neutrons resulting in small amounts of <sup>228</sup>Ac. After the synthesis, actinium is separated from radium and from the products of decay and nuclear fusion, such as thorium, polonium, lead and bismuth. The extraction can be performed with [[thenoyltrifluoroacetone]]-[[benzene]] solution from an aqueous solution of the radiation products, and the selectivity to a certain element is achieved by adjusting the [[pH]] (to about 6.0 for actinium).<ref name="Hagemann1950" /> An alternative procedure is anion exchange with an appropriate [[resin]] in [[nitric acid]], which can result in a separation factor of 1,000,000 for radium and actinium vs. thorium in a two-stage process. Actinium can then be separated from radium, with a ratio of about 100, using a low cross-linking cation exchange resin and nitric acid as [[eluant]].<ref name="sep" />

<sup>225</sup>Ac was first produced artificially at the [[Institute for Transuranium Elements]] (ITU) in Germany using a [[cyclotron]] and at [[St George Hospital (Sydney)|St George Hospital]] in Sydney using a [[Linear particle accelerator|linac]] in 2000.<ref>{{cite journal |doi = 10.1016/j.apradiso.2008.11.012 |date = 2009 |author = Melville, G |author2 = Allen, Bj |title = Cyclotron and linac production of Ac-225 |volume = 67 |issue = 4 |pages = 549–55 |pmid = 19135381 |journal = Applied Radiation and Isotopes|bibcode = 2009AppRI..67..549M }}</ref> This rare isotope has potential applications in radiation therapy and is most efficiently produced by bombarding a radium-226 target with 20–30&nbsp;MeV [[deuterium]] ions. This reaction also yields <sup>226</sup>Ac which however decays with a half-life of 29 hours and thus does not contaminate <sup>225</sup>Ac.<ref>{{cite book |last1=Russell |first1=Pamela J. |last2=Jackson |first2=Paul |last3=Kingsley |first3=Elizabeth Anne |year=2003 |url=https://books.google.com/books?id=K1y6k5bdlWkC&pg=PA336 |title=Prostate cancer methods and protocols |publisher=Humana Press |isbn=0-89603-978-1 |page=336}}{{Dead link|date=April 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Actinium metal has been prepared by the reduction of actinium fluoride with [[lithium]] vapor in vacuum at a temperature between {{cvt|1100|and|1300|°C}}. Higher temperatures resulted in evaporation of the product and lower ones lead to an incomplete transformation. Lithium was chosen among other [[alkali metal]]s because its fluoride is most volatile.<ref name="CRC">Hammond, C. R. ''The Elements'' in {{RubberBible86th}}</ref><ref name="blueglow" />