Comparison of thermal expansion of Tc and Re salts

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dc.contributor.authorThorogood, GJen_AU
dc.contributor.authorKennedy, BJen_AU
dc.contributor.authorReynolds, EMen_AU
dc.contributor.authorPoineau, Fen_AU
dc.contributor.authorYu, Men_AU
dc.contributor.authorInjac, Sen_AU
dc.date.accessioned2022-04-14T01:15:05Zen_AU
dc.date.available2022-04-14T01:15:05Zen_AU
dc.date.issued2017-10-29en_AU
dc.date.statistics2022-03-28en_AU
dc.description.abstract99Tc is the most significant long-lived product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste. Tc 7+ compounds are highly mobile in the environment. Relatively little is known regarding the solid state chemistry of Tc. Recently we studied the structural properties of (NH4)TcO4 (Tc7+) and confirmed that this is isostructural with (NH4)ReO4 adopting a tetragonal scheelite type structure in space group I41/a. The unit cell parameters of (NH4)TcO4 are strongly temperature dependent with the structure showing negative thermal expansion along both the a- and c-axis, albeit at different temperatures This behavior is significantly different to that previously reported for the isostructural oxide (NH4)ReO4, although we note that the data for (NH4)ReO4 was collected at much lower resolution. Nevertheless it is clear in the literature that the thermal expansion behavior of (NH4)ReO4 is highly anisotropic. Despite the difference in the thermal expansion between what we have observed for (NH4)TcO4 and that described by others for (NH4)ReO4 it is likely that the origin of the anomalous thermal expansion in is the same in both cases, namely it is a consequence of re-orientation of the ammonium ions in the surrounding cage of eight oxygen atoms. To verify this for (NH4)TcO4 requires we replace the ammonium cation with another small cation. Therefore we have compared the thermal behavior of AReO4 with ATcO4 to determine if Re oxides are suitable surrogates to predict the behavior of Tc oxides and how they may behave in the environment.en_AU
dc.identifier.citationThorogood, G., Kennedy, B., Reynolds, E., Poineau, F. & Injac, S. (2017). Comparison of thermal expansion of Tc and Re salts. Paper presented at MRS2017 - Scientific Basis for Nuclear Waste Management Symposium 2017, Sydney, Australia, 29 October to 3 November 2017, (pp. 11). Retrieved from: https://events01.synchrotron.org.au/event/51/overviewen_AU
dc.identifier.conferenceenddate3 November 2017en_AU
dc.identifier.conferencenameMRS2017 - Scientific Basis for Nuclear Waste Management Symposium 2017en_AU
dc.identifier.conferenceplaceSydney, Australiaen_AU
dc.identifier.conferencestartdate29 October 2017en_AU
dc.identifier.pagination11en_AU
dc.identifier.urihttps://events01.synchrotron.org.au/event/51/overviewen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13004en_AU
dc.language.isoenen_AU
dc.publisherMaterials Research Society (MRS)en_AU
dc.subjectTechnetium oxidesen_AU
dc.subjectRadioactive wastesen_AU
dc.subjectThermal expansionen_AU
dc.subjectOxygenen_AU
dc.subjectCationsen_AU
dc.subjectEnvironmental effectsen_AU
dc.titleComparison of thermal expansion of Tc and Re saltsen_AU
dc.typeConference Abstracten_AU
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