Details

Autor(en) / Beteiligte

• Labs, Sabrina
• Hennig, Christoph
• Weiss, Stephan
• Curtius, Hilde
• Zaenker, Harald
• Bosbach, Dirk

Titel

Synthesis of Coffinite, USiO sub( 4), and Structural Investigations of U sub( x) Th sub( (1-x))SiO sub( 4) Solid Solutions

Ist Teil von

• Environmental science & technology, 2014-01, Vol.48 (1), p.854-854

Erscheinungsjahr

2014

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The miscibility behavior of the USiO sub( 4-)ThSiO sub( 4) system was investigated. The end members and 10 solid solutions U sub( x)Th sub( (1-x))SiO sub( 4) with x = 0.12-0.92 were successfully synthesized, without formation of other secondary uranium or thorium phases. Lattice parameters of the solid solutions evidently follow Vegard's Law. Investigation of the local structure with EXAFS reveals small differences between the U and Th environment attributed to different atomic radii of the metal atoms but no implications for a miscibility gap. The data provided confirm complete miscibility for the system USiO sub( 4-)ThSiO sub( 4). The structure of the end members was studied in detail with XRD and discussed with special regard to the oxygen positions and the often neglected Si-O bond length. USiO sub( 4) could be obtained without UO sub( 2) impurities and the lattice parameters derived from Rietveld refinement as c = 6.2606(3) A and alpha = 6.9841(3) A. The Si-O distance in USiO sub( 4) appears to be 1.64 A, which is more reasonable than earlier reported values.