Assessment of the U3O7 Crystal Structure by X-ray and Electron Diffraction

Gregory Leinders; Rémi Delville; Janne Pakarinen; Thomas Cardinaels; Koen Binnemans; Marc Verwerft

doi:10.1021/acs.inorgchem.6b01941

Assessment of the U₃O₇ Crystal Structure by X-ray and Electron Diffraction

Gregory Leinders^*
, Rémi Delville
, Janne Pakarinen
, Thomas Cardinaels
, Koen Binnemans
, Marc Verwerft

^*Corresponding author for this work

Not published at VTT

Research output: Contribution to journal › Article › Scientific › peer-review

30 Citations (Scopus)

Abstract

Polycrystalline U₃O₇ powder was synthesized by oxidation of UO₂ powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U₃O₇ phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U₄O_9-ϵ (more precisely U₆₄O₁₄₃), U₃O₇ exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO₂. Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U₁₅O₃₅), and spanned by basis vectors A = a_p - 2b_p, B = -2a_p + b_p, and C = 3c_p (lattice parameters of the subcell are a_p = b_p = 538.00 ± 0.02 pm and c_p = 554.90 ± 0.02 pm; c_p/a_p = 1.031). The arrangement of cuboctahedra in U₃O₇ results in a layered structure, which is different from the well-known U₄O_9-ϵ crystal structure.

Original language	English
Pages (from-to)	9923-9936
Number of pages	14
Journal	Inorganic Chemistry
Volume	55
Issue number	19
DOIs	https://doi.org/10.1021/acs.inorgchem.6b01941
Publication status	Published - 3 Oct 2016
MoE publication type	A1 Journal article-refereed

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@article{1cac080aa3b345d3b3f7fdbe53bab21b,

title = "Assessment of the U3O7 Crystal Structure by X-ray and Electron Diffraction",

abstract = "Polycrystalline U3O7 powder was synthesized by oxidation of UO2 powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U3O7 phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U4O9-ϵ (more precisely U64O143), U3O7 exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO2. Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U15O35), and spanned by basis vectors A = ap - 2bp, B = -2ap + bp, and C = 3cp (lattice parameters of the subcell are ap = bp = 538.00 ± 0.02 pm and cp = 554.90 ± 0.02 pm; cp/ap = 1.031). The arrangement of cuboctahedra in U3O7 results in a layered structure, which is different from the well-known U4O9-ϵ crystal structure.",

author = "Gregory Leinders and R{\'e}mi Delville and Janne Pakarinen and Thomas Cardinaels and Koen Binnemans and Marc Verwerft",

note = "Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

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T1 - Assessment of the U3O7 Crystal Structure by X-ray and Electron Diffraction

AU - Leinders, Gregory

AU - Delville, Rémi

AU - Pakarinen, Janne

AU - Cardinaels, Thomas

AU - Binnemans, Koen

AU - Verwerft, Marc

PY - 2016/10/3

Y1 - 2016/10/3

N2 - Polycrystalline U3O7 powder was synthesized by oxidation of UO2 powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U3O7 phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U4O9-ϵ (more precisely U64O143), U3O7 exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO2. Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U15O35), and spanned by basis vectors A = ap - 2bp, B = -2ap + bp, and C = 3cp (lattice parameters of the subcell are ap = bp = 538.00 ± 0.02 pm and cp = 554.90 ± 0.02 pm; cp/ap = 1.031). The arrangement of cuboctahedra in U3O7 results in a layered structure, which is different from the well-known U4O9-ϵ crystal structure.

AB - Polycrystalline U3O7 powder was synthesized by oxidation of UO2 powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U3O7 phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U4O9-ϵ (more precisely U64O143), U3O7 exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO2. Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U15O35), and spanned by basis vectors A = ap - 2bp, B = -2ap + bp, and C = 3cp (lattice parameters of the subcell are ap = bp = 538.00 ± 0.02 pm and cp = 554.90 ± 0.02 pm; cp/ap = 1.031). The arrangement of cuboctahedra in U3O7 results in a layered structure, which is different from the well-known U4O9-ϵ crystal structure.

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DO - 10.1021/acs.inorgchem.6b01941

M3 - Article

AN - SCOPUS:84990068793

SN - 0020-1669

VL - 55

SP - 9923

EP - 9936

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 19

ER -

Assessment of the U₃O₇ Crystal Structure by X-ray and Electron Diffraction

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