Structural Study of the Ammonium Octafluoroneptunate, [NH4]4NpF8

Authors

Frederic Poineau, University of Nevada, Las VegasFollow
Chinthaka M. Silva, Oak Ridge National Laboratory
Charles B. Yeamans, Lawrence Livermore National LaboratoryFollow
Gary S. Cerefice, University of Nevada, Las Vegas
Alfred P. Sattelberger, University of Nevada, Las VegasFollow
Kenneth R. Czerwinski, University of Nevada, Las VegasFollow

Document Type

Article

Publication Date

1-1-2016

Publication Title

Inorganica Chimica Acta

Volume

448

First page number:

93

Last page number:

96

Abstract

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, β = 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. © 2016 Elsevier B.V. All rights reserved.

Keywords

EXAFS; Fluoride; Neptunium

Language

English

Repository Citation

Poineau, F., Silva, C. M., Yeamans, C. B., Cerefice, G. S., Sattelberger, A. P., Czerwinski, K. R. (2016). Structural Study of the Ammonium Octafluoroneptunate, [NH4]4NpF8. Inorganica Chimica Acta, 448 93-96.
http://dx.doi.org/10.1016/j.ica.2016.04.025