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The crystal structures of CeSiO4 and Ca2Ce8(SiO4)6O2

Published online by Cambridge University Press:  10 January 2013

J. M. S. Skakle ,
C. L. Dickson  and
F. P. Glasser
J. M. S. Skakle
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, United Kingdom
C. L. Dickson
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, United Kingdom
F. P. Glasser
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, United Kingdom
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Abstract

Two new solubility-limiting phases relevant to nuclear waste disposal are reported, namely CeSiO4 and Ca2Ce8(SiO4)O2, produced by hydrothermal synthesis at 180 °C. X-ray diffraction data are presented for both compounds. Rietveld refinement was performed for each of these phases. CeSiO4 was confirmed to be a zircon structure type, with space group I41/amd, unit cell type="bold">abold=6.9564(3), type="bold">cbold=6.1953(4) Å. Bond lengths for SiO4 are in excellent agreement with published values; Ce4+ is coordinated to eight oxygen atoms with four regular and four short bonds. Ca2Ce8(SiO4)O2 was shown to have an apatite structure, with space group P63/m and unit cell type="bold">abold=9.4343(3), type="bold">cbold=6.8885(4) Å. The unit cell and bond lengths were found to be slightly smaller than would be expected from other lanthanide-containing analogs; possible reasons for this are discussed.

Keywords

Rietveld refinementpowder diffractionactinide simulantscementnuclear waste disposal
Type
New Diffraction Data
Information
Powder Diffraction , Volume 15 , Issue 4 , December 2000 , pp. 234 - 238
Copyright
Copyright © Cambridge University Press 2000

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