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

J. M.S. Skakle; C. L. Dickson; F. P. Glasser

doi:10.1017/S0885715600011143

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

J. M.S. Skakle^*, C. L. Dickson, F. P. Glasser

^*Corresponding author for this work

University of Aberdeen

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

34 Citations (Scopus)

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 a=6.9564(3), c=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 a=9.4343(3), c = 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.

Original language	English
Pages (from-to)	234-238
Number of pages	5
Journal	Powder Diffraction
Volume	15
Issue number	4
DOIs	https://doi.org/10.1017/S0885715600011143
Publication status	Published - 31 Dec 2000

Keywords

Actinide simulants
Cement
Disposal
Nuclear waste
Powder diffraction
Rietveld refinement

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title = "The crystal structures of CeSiO4 and Ca2Ce8(SiO4)6O2",

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 a=6.9564(3), c=6.1953(4) {\AA}. 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 a=9.4343(3), c = 6.8885(4) {\AA}. 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 = "Actinide simulants, Cement, Disposal, Nuclear waste, Powder diffraction, Rietveld refinement",

author = "Skakle, {J. M.S.} and Dickson, {C. L.} and Glasser, {F. P.}",

year = "2000",

month = dec,

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doi = "10.1017/S0885715600011143",

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T1 - The crystal structures of CeSiO4 and Ca2Ce8(SiO4)6O2

AU - Skakle, J. M.S.

AU - Dickson, C. L.

AU - Glasser, F. P.

PY - 2000/12/31

Y1 - 2000/12/31

N2 - 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 a=6.9564(3), c=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 a=9.4343(3), c = 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.

AB - 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 a=6.9564(3), c=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 a=9.4343(3), c = 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.

KW - Actinide simulants

KW - Cement

KW - Disposal

KW - Nuclear waste

KW - Powder diffraction

KW - Rietveld refinement

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DO - 10.1017/S0885715600011143

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SN - 0885-7156

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JO - Powder Diffraction

JF - Powder Diffraction

IS - 4

ER -

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

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