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Title: Structural study of the ammonium octafluoroneptunate, [NH 4] 4NpF 8

The [NH 4] 4NpF 8 salt was prepared from the solid-state reaction of NpO 2 with NH 4HF 2 and characterized by powder X-ray diffraction and X-ray absorption fine structure spectroscopy. The diffraction results confirm the compound to be isostructural to [NH 4] 4UF 8 with the following lattice parameter (a = 13.054(4) Å, b = 6.681(2) Å, c = 13.676(5) Å, ß = 121.14 Å). For the first time, a Neptunium fluoride complex has been characterized by XAFS spectroscopy. The energy position of the white line and inflection of the XANES spectra of [NH 4] 4NpF 8 are consistent with the presence of Np(IV). Adjustment of the EXAFS spectra indicates that the coordination number (7.4±1.5) and the average Np-F distance (2.26(1) Å) are consistent with the presence of the NpF8 dodecahedron. The average Np-F distance is ~0.02 Å shorter than the U-F distance in [NH 4] 4UF 8 and is a result of the actinide contraction.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1]
  1. Univ. of Nevada, Las Vegas, NV (United States). Dept. of Chemistry
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Univ. of Nevada, Las Vegas, NV (United States). Dept. of Health Physics
  5. Univ. of Nevada, Las Vegas, NV (United States). Dept. of Chemistry; Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Inorganica Chimica Acta
Additional Journal Information:
Journal Volume: 448; Journal Issue: C; Journal ID: ISSN 0020-1693
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; EXAFS; Fluoride; Neptunium
OSTI Identifier:
1330088
Alternate Identifier(s):
OSTI ID: 1359174

Poineau, Frederic, Silva, Chinthaka M., Yeamans, Charles B., Cerefice, Gary S., Sattelberger, Alfred P., and Czerwinski, Kenneth R.. Structural study of the ammonium octafluoroneptunate, [NH4]4NpF8. United States: N. p., Web. doi:10.1016/j.ica.2016.04.025.
Poineau, Frederic, Silva, Chinthaka M., Yeamans, Charles B., Cerefice, Gary S., Sattelberger, Alfred P., & Czerwinski, Kenneth R.. Structural study of the ammonium octafluoroneptunate, [NH4]4NpF8. United States. doi:10.1016/j.ica.2016.04.025.
Poineau, Frederic, Silva, Chinthaka M., Yeamans, Charles B., Cerefice, Gary S., Sattelberger, Alfred P., and Czerwinski, Kenneth R.. 2016. "Structural study of the ammonium octafluoroneptunate, [NH4]4NpF8". United States. doi:10.1016/j.ica.2016.04.025. https://www.osti.gov/servlets/purl/1330088.
@article{osti_1330088,
title = {Structural study of the ammonium octafluoroneptunate, [NH4]4NpF8},
author = {Poineau, Frederic and Silva, Chinthaka M. and Yeamans, Charles B. and Cerefice, Gary S. and Sattelberger, Alfred P. and Czerwinski, Kenneth R.},
abstractNote = {The [NH4]4NpF8 salt was prepared from the solid-state reaction of NpO2 with NH4HF2 and characterized by powder X-ray diffraction and X-ray absorption fine structure spectroscopy. The diffraction results confirm the compound to be isostructural to [NH4]4UF8 with the following lattice parameter (a = 13.054(4) Å, b = 6.681(2) Å, c = 13.676(5) Å, ß = 121.14 Å). For the first time, a Neptunium fluoride complex has been characterized by XAFS spectroscopy. The energy position of the white line and inflection of the XANES spectra of [NH4]4NpF8 are consistent with the presence of Np(IV). Adjustment of the EXAFS spectra indicates that the coordination number (7.4±1.5) and the average Np-F distance (2.26(1) Å) are consistent with the presence of the NpF8 dodecahedron. The average Np-F distance is ~0.02 Å shorter than the U-F distance in [NH4]4UF8 and is a result of the actinide contraction.},
doi = {10.1016/j.ica.2016.04.025},
journal = {Inorganica Chimica Acta},
number = C,
volume = 448,
place = {United States},
year = {2016},
month = {4}
}