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Latest revision as of 05:56, 15 November 2024 edit undoGraeme Bartlett (talk | contribs)Administrators249,524 edits CHEMSPIDER |
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| ImageSize = 250px |
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| verifiedrevid = 404138578 |
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| IUPACName = americium(IV) oxide |
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| ImageFile = Americium_oxide.png |
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| OtherNames = |
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| ImageFile_Ref = {{Chemboximage|correct|yes}} |
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| Section1 = {{Chembox Identifiers |
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| ImageSize = 244 |
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| ImageName = Americium dioxide |
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| IUPACName = Americium(IV) oxide |
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| SystematicName = |
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|Section1={{Chembox Identifiers |
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| CASNo_Ref = {{cascite|correct|??}} |
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| CASNo = 12005-67-3 |
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| CASNo = 12005-67-3 |
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| ChemSpiderID = 64878971 |
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| PubChem = |
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| SMILES = }} |
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| PubChem = 57461988 |
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| EC_number = 234-471-0 |
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| Section2 = {{Chembox Properties |
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| MeSHName = |
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| Formula = AmO<sub>2</sub> |
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| SMILES = .. |
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| MolarMass = 275.06 g/mol |
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| StdInChI = 1S/Am.2O/q+4;2*-2 |
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| Appearance = black / gold streak |
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| StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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| Density = |
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| StdInChIKey = GABXYUQCUHMHDP-UHFFFAOYSA-N |
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| Section3 = {{Chembox Structure |
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|Section2={{Chembox Properties |
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| Am=1 | O=2 |
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| CrystalStruct = ] (cubic), ] |
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| Appearance = Black crystals |
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| SpaceGroup = Fm<u style="text-decoration:overline">3</u>m, No. 225 |
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| Density = 11.68 g/cm<sup>3</sup> |
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| MeltingPtC = 2113 |
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| MeltingPt_ref = <ref name="cry" /> |
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|Section3={{Chembox Structure |
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| Structure_ref=<ref name="cry">{{cite journal |author1=Christine Guéneau |author2=Alain Chartier |author3=Paul Fossati |author4=Laurent Van Brutzel |author5=Philippe Martin |title=Thermodynamic and Thermophysical Properties of the Actinide Oxides |journal=Comprehensive Nuclear Materials 2nd Ed. |date=2020 |volume=7 |pages=111–154 |doi=10.1016/B978-0-12-803581-8.11786-2 |isbn=9780081028667 |s2cid=261051636 |language=en}}</ref> |
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| CrystalStruct = ] (cubic), ] |
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| SpaceGroup = Fm{{overline|3}}m, No. 225 |
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| LattConst_a = 537.6 pm |
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|OtherCations = ]<br>] |
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'''Americium dioxide''' (AmO<sub>2</sub>) is a black<ref name = G&E>{{cite book | last1 = Greenwood | first1 = Norman N. | last2 = Earnshaw | first2 = Alan | title = Chemistry of the Elements | edition = 2nd | year = 1997 | publisher = ] | isbn = 978-0750633659 | page = 1267 | name-list-style = amp | ol = OL689297M | oclc = 1005231772 | lccn = 97036336 }}</ref> compound of ]. In the solid state, AmO<sub>2</sub> adopts a ] (like ]).<ref>{{Cite book | last1 = Wells | first1 = Alexander Frank | title = Structural inorganic chemistry | year = 1984 | publisher = ] | location = Oxford | isbn = 978-0-19-855370-0}}</ref> It is used as a source of ]s. |
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==Historical context== |
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'''Americium dioxide''' (AmO<sub>2</sub>) is a compound of ]. It is used as a source of ]s, particularly in ionisation-type ]s. In the solid state AmO<sub>2</sub> adopts the fluorite, ] structure.<ref> Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications ISBN 0-19-855370-6 </ref> |
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The demand for americium dioxide stems from the difficulty of storing the element americium as a solution of ] because the alpha radiation and ] decomposes storage containers over time. To solve the liquid storage problem, scientists at ] devised a synthesis to turn liquid americium–acid solution into a precipitated form of americium for safer handling and more efficient storage.<ref name="ORNL">{{cite web |url= http://www.ornl.gov/info/reports/1960/3445603615461.pdf |title= Preparation of Americium Dioxide by Thermal Decomposition of Americium Oxalate in Air |date= December 1960 |publisher= Oak Ridge National Laboratory |access-date= 2 May 2013 }}{{Dead link|date=October 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> |
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==References== |
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{{reflist}} |
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==External links== |
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==Synthesis== |
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Synthesis of americium dioxide, as described by the Oak Ridge National Laboratory in 1960, starts by dissolving americium in hydrochloric acid, and then neutralizing the excess acid with ] ({{chem|NH|4|OH}}). Then, saturated ] solution ({{chem|C|2|H|2|O|4}}) is added to the now neutralized solution to precipitate dull pink americium(III) ] crystals; once complete precipitation is achieved, additional ] is added to make a slurry. The slurry of americium oxalate and oxalic acid is next agitated before the americium oxalate is filtered out, washed with water, and partially dried in air.<ref name="ORNL" /> |
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The americium oxalate is then ] in a ] boat. It is first dried in a furnace at {{convert|150|C}} and then heated to {{convert|350|C}}. When decomposition begins to occur, the oxalate will turn into the desired black americium dioxide; to ensure no oxalate remains in the newly forming dioxide, the oven temperature is increased and held at {{convert|800|C}} then slowly allowed to cool to room temperature.<ref name="ORNL" /> |
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==Modern applications== |
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Americium dioxide is the most widely used americium compound in ionising smoke detectors. The dioxide form is insoluble in water, making it relatively safe to handle in production. |
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In the late 2010s, americium dioxide has been of interest to ] as power source for ] (RTGs) for ] spacecraft and ]. A fully automated ] to produce americium dioxide was developed by nuclear researchers from the ] to be implemented on the ] nuclear site in ], ]. It is based on the same principles as the historic production method developed at Oak Ridge National Laboratory.<ref>{{cite journal |title=Am2RTG: Am2RTG: Fully Autonomous, Rad-Hard Americium Nitrate to Americium Dioxide Conversion Process Flow for Radioisotope Thermoelectric Generators |last1=Verbelen |first1=Yannick |last2=Megson-Smith |first2=David |first3=Erin |last3=Holland |doi=10.13140/RG.2.2.28490.80320 |year=2020 |url=https://www.researchgate.net/publication/348555938}}</ref> |
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==Americium-aluminium alloys== |
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Americium-aluminium alloys can be formed by melting americium dioxide with aluminium and an additional ].<ref>{{ cite web |url= http://patent.ipexl.com/GB/GB1343961.html |archive-url= https://archive.today/20130629124332/http://patent.ipexl.com/GB/GB1343961.html |url-status= dead |archive-date= 2013-06-29 |title= Preparation of Americium-Aluminium Alloys |date= January 1974 |publisher= KERNFORSCHUNG GMBH GES FUER |access-date= May 3, 2013 }}</ref> The created alloy can undergo neutron irradiation to produce other ] ].<ref name="DoH">{{cite web |url= http://www.atsdr.cdc.gov/toxprofiles/tp156.pdf |title= Toxicological profile for americium |date=April 2004 |publisher= U.S. Department of Health and Human Services |access-date=15 January 2011}}</ref> |
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==References== |
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{{Reflist}} |
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{{Americium compounds}} |
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{{oxides}} |
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