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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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References

Allman, R. (1975). “Relations between bond lengths and bond strengths in oxide structures,” Monatsh. Chem. 106, 779–793.Google Scholar
Aoki, H. (1991). Science and Medical Applications of Hydroxyapatite (Japanese Association of Apatite Science (JAAS), Takayama Press System Center, Tokyo), pp. 11–19.Google Scholar
Brown, I. D. (1991). “The influence of internal strain on the charge distribution and superconducting transition in Ba 2YCu 3O x,”J. Solid State Chem. 90, 155–157.CrossRefGoogle Scholar
Cooper, M. J., and Sayer, J. P. (1975). “The asymmetry of neutron powder diffraction peaks,” J. Appl. Crystallogr. 8, 615–618.CrossRefGoogle Scholar
Fahey, J. A., Weber, W. J., and Rotella, F. J. (1985). “An X-ray and neutron powder diffraction study of the Ca 2+xNd 8−x(SiO 4)6O 2−0.5x system,” J. Solid State Chem. 60, 145–158.CrossRefGoogle Scholar
Fletcher, D. A., McMeeking, R. F., and Parkin, D. (1996). “The United Kingdom Chemical Database Service,” J. Chem. Inf. Comput. Sci. 36, 726.CrossRefGoogle Scholar
Fuchs, L. H., and Gebert, E. (1958). “X-ray studies of synthetic coffinite, thorite and uranothorites,” Am. Mineral. 43, 243–248.Google Scholar
Fuhrmann, J., and Pickardt, J. (1986). “On the formation of HfSiO 4 single crystals by chemical transport reactions,” Z. Anorg. Allg. Chem. 532, 171–174.CrossRefGoogle Scholar
Hazen, R. M., and Finger, L. W. (1979). “Crystal structure and compressibility of zircon at high pressure,” Am. Mineral. 64, 196–201.Google Scholar
Howard, C. J. (1982). “The approximation of asymmetric neutron-powder-diffraction peaks by sums of Gaussians,” J. Appl. Crystallogr. 15, 615–620.CrossRefGoogle Scholar
Keller, C. (1963). “Investigations of germanates and silicates of the type ABO 4 with quadrivalent elements thorium to americium,” Nukleonik 5, 41–48.Google Scholar
Mursic, Z., Vogt, T., Boysen, H., and Frey, F. (1992). “Single-crystal neutron diffraction study of metamict zircon up to 2000 K,” J. Appl. Crystallogr. 25, 519–523.CrossRefGoogle Scholar
Powder Diffraction File, International Centre for Diffraction Data, Pennsylvania.Google Scholar
Robinson, K., Gibbs, G. V., and Ribbe, P. H. (1971). “The structure of zircon: A comparison with garnet,” Am. Mineral. 56, 782–790.Google Scholar
Shannon, R. D. (1976). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. A32, 751–767.CrossRefGoogle Scholar
Speer, J. A., and Cooper, B. J. (1982). “Crystal structure of synthetic hafnon, HfSiO 4, comparison with zircon and the actinide orthosilicates,” Am. Mineral. 67, 804–808.Google Scholar
Taylor, M., and Ewing, R. C. (1978). “The crystal structures of the ThSiO 4 polymorphs: Huttonite and thorite,” Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. B34, 1074–1079.CrossRefGoogle Scholar
Thomas, M. W. (1977). “Peak shifts and peak broadening in powder neutron-diffraction patterns due to finite aperture counters,” J. Appl. Crystallogr. 10, 12–13.CrossRefGoogle Scholar
Von Dreele, R. B., and Larson, A. C. (1998). GSAS-Generalised Crystal Structure Analysis System, Neutron Scattering Centre, Los Alamos National Laboratory, California.Google Scholar
Whitfield, H. J., Roman, D., and Palmer, A. R. (1966). “X-ray study of the system ThO 2–CeO 2–Ce 2O 3,”J. Inorg. Nucl. Chem. 28, 2817–2825.CrossRefGoogle Scholar
Zachariasen, W. H. (1978). “Bond lengths in oxygen and halogen compounds of d and f elements,” J. Less-Common Met. 62, 1–7.CrossRefGoogle Scholar