@article{40e5a8c4c26048eda0b9836e444242e8,
title = "Structure and thermodynamic stability of UTa3O10, a U(v)-bearing compound",
abstract = "Heating a mixture of uranyl(vi) nitrate and tantalum(v) oxide in the molar ratio of 2:3 to 1400 °C resulted in the formation of a new compound, UTa3O10. The honey colored to yellow brown crystals of UTa3O10 crystallize in an orthorhombic structure with the space group Fddd (no. 70), lattice parameters a = 7.3947(1), b = 12.7599(2), c = 15.8156(2) {\AA}, and Z = 8. Vertex sharing [TaO6]7- octahedra of two crystallographically distinct Ta cations form a three dimensional tantalate framework. Within this framework, six membered rings of [TaO6]7- octahedra are formed within the (001) plane. The center of these rings is occupied by the uranyl cations [UO2]+, with an oxidation state of +5 for uranium. The pentavalence of U and Ta was confirmed by X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy. The enthalpy of formation of UTa3O10 from Ta2O5, β-U3O7, and U3O8 has been determined to be 13.1 ± 18.1 kJ mol-1 using high temperature oxide melt solution calorimetry with sodium molybdate as the solvent at 700 °C. The close to zero enthalpy of formation of UTa3O10 can be explained by closely balanced structural stabilizing and destabilizing factors, which may also apply to other UM3O10 compounds.",
author = "Xiaofeng Guo and Christian Lipp and Eitan Tiferet and Antonio Lanzirotti and Matthew Newville and Engelhard, {Mark H.} and Di Wu and Ilton, {Eugene S.} and Sutton, {Stephen R.} and Hongwu Xu and Burns, {Peter C.} and Alexandra Navrotsky",
note = "Funding Information: This paper is based on work supported as part of the Materials Science of Actinides, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001089. X. G was also supported by a Seaborg postdoctoral fellowship from the Laboratory Directed Research and Development (LDRD) program, through the G. T. Seaborg Institute, of Los Alamos National Laboratory (LANL), which is operated by Los Alamos National Security LLC, under DOE Contract DE-AC52-06NA25396. The XAS work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation Earth Sciences (EAR-1128799) and Department of Energy GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract no. DE-AC02-06CH11357. The XPS analyses were performed using EMSL, a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. PNNL is operated by Battelle for the U.S. DOE under contract DE-AC06-76RLO1930. We thank Qi Liang and Mark Asta for their preliminary computational work, discussion. Publisher Copyright: {\textcopyright} 2016 The Royal Society of Chemistry.",
year = "2016",
doi = "10.1039/c6dt02843h",
language = "English (US)",
volume = "45",
pages = "18892--18899",
journal = "Dalton Transactions",
issn = "1477-9226",
publisher = "Royal Society of Chemistry",
number = "47",
}