Ab initio crystal structure determination of uranium orthophosphate by conventional X-ray powder diffraction

被引：0

作者：

Benard, P. ^{[1
]}

Louer, D. ^{[1
]}

Dacheux, N. ^{[1
]}

Brandel, V. ^{[1
]}

Genet, M. ^{[1
]}

机构：

[1] Universite de Rennes I, Rennes, France

来源：

Materials Science Forum | 1994年 / 166-169卷 / pt 2期

关键词：

Atoms - Crystal symmetry - Electron energy levels - Lattice constants - Oxygen - Three dimensional - Uranium compounds - X ray powder diffraction;

D O I：

10.4028/www.scientific.net/msf.166-169.625

中图分类号：

学科分类号：

摘要：

U(UO2)(PO4)2 has a triclinic symmetry, space group P1¯ (Z = 2), and lattice parameters a = 8.8212(4) angstroms, b = 9.2173(5) angstroms, c = 5.4772(3) angstroms, α = 102.622(4)°, β = 97.748(4)°, γ = 102.459(5)°. Its structure was solved ab initio from conventional X-ray powder diffraction data (Cu Kα1 radiation) and refined by the Rietveld method to Rwp = 0.14 and RF = 0.04 for 1240 reflections. The uranium atoms are sevenfold oxygen coordinated in the shape of pentagonal bipyramid sharing two opposite edges to form PaCl5-type chains following the [(U(1))2-(U(2))2]n sequence. One of the two independent uranium atoms U(2) exists as a linear uranyl entity (O-U-O)2+, with five additional oxygen atoms in a perpendicular plane. The uranium orthophosphate may be considered as a mixed-valence compound with oxidation states +4 and +6. Bidentate phosphate groups allow for a connection between the chains to generate a three dimensional network.

引用

页码：625 / 630