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Solid-state syntheses and single-crystal characterizations of three tetravalent thorium and uranium silicates.
- Source :
-
Journal of Solid State Chemistry . Jan2015, Vol. 221, p405-410. 6p. - Publication Year :
- 2015
-
Abstract
- Colorless crystals of ThSiO 4 (huttonite) ( 1 ) and (Ca 0.5 Na 0.5 ) 2 NaThSi 8 O 20 ( 2 ) have been synthesized by the solid-state reactions of ThO 2 , CaSiO 3 , and Na 2 WO 4 at 1073 K. Green crystals of (Ca 0.5 Na 0.5 ) 2 NaUSi 8 O 20 ( 3 ) have been synthesized by the solid-state reactions of UO 2 , CaSiO 3 , and Na 2 WO 4 at 1003 K. All three compounds have been characterized by single-crystal X-ray diffraction. Compound 1 adopts a monazite-type three-dimensional condensed structure, which is built from edge- and corner-shared ThO 9 polyhedra and SiO 4 tetrahedra. Compounds 2 and 3 are isostructural and they crystallize in a steacyite-type structure. The structure consists of discrete pseudocubic [Si 8 O 20 ] 8− polyanions, which are connected by An 4+ cations into a three-dimensional framework. Each An atom coordinates to eight monodentate [Si 8 O 20 ] 8− moieties in a square antiprismatic geometry. Na + and Ca 2+ ions reside in the void within the framework. Raman spectra of 1 , 2 , and 3 were collected on single crystal samples. 1 displays more complex vibrational bands than thorite. Raman spectra of 2 and 3 are analogous with most of vibrational bands located at almost the same regions. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00224596
- Volume :
- 221
- Database :
- Academic Search Index
- Journal :
- Journal of Solid State Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 99900196
- Full Text :
- https://doi.org/10.1016/j.jssc.2014.10.018