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Synthesis and structural study of five new trisilicates, BaREE (sub 2) Si (sub 3) O (sub 10) (REE=Gd, Er, Yb, Sc) and SrY (sub 2) Si (sub 3) O (sub 10) , including a review on the geometry of the Si (sub 3) O (sub 10) unit

Maria Wierzbicka-Wieczorek, Uwe Kolitsch and Ekkehart Tillmanns
Synthesis and structural study of five new trisilicates, BaREE (sub 2) Si (sub 3) O (sub 10) (REE=Gd, Er, Yb, Sc) and SrY (sub 2) Si (sub 3) O (sub 10) , including a review on the geometry of the Si (sub 3) O (sub 10) unit
European Journal of Mineralogy (March 2010) 22 (2): 245-258

Abstract

Five new mixed-framework trisilicates were synthesised using a high-temperature flux growth technique. Colourless, glassy plates of SrY (sub 2) Si (sub 3) O (sub 10) crystallise in space group P1, with a=6.757(1), b=6.885(1), c=9.273(2) Aa, alpha =72.42(3), beta =86.37(3), gamma =88.37(3) degrees , V=410.38(12) Aa (super 3) , Z=2. The main building units of the new structure type represented by SrY (sub 2) Si (sub 3) O (sub 10) are slightly curved Si (sub 3) O (sub 10) trimers and Y (sub 2) O (sub 11) dimers (composed of YO (sub 6) octahedra sharing an edge with YO (sub 7) polyhedra), which are further edge-connected to adjacent dimers to form twisted zigzag chains parallel to [010]. BaREE (sub 2) Si (sub 3) O (sub 10) (REE=Gd, Er, Yb, Sc) form colourless small prisms, pseudohexagonal plates or isometric crystals, and crystallise in space group P2 (sub 1) /m, with respectively a=5.435(1) / 5.389(1) / 5.377(1) / 5.273(1), b=12.241(2) / 12.163(2) / 12.117(2) / 11.918(2), c=6.932(1) / 6.840(1) / 6.790(1) / 6.591(1) Aa, beta =106.26(3) / 106.47(3) / 106.50(3) / 107.06(3) degrees , V=442.74(13) / 429.94(12) / 424.17(12) / 395.98(12) Aa (super 3) , Z=2. BaREE (sub 2) Si (sub 3) O (sub 10) (REE=Gd, Er, Yb, Sc) are isotypic with BaY (sub 2) Si (sub 3) O (sub 10) . Their topology is characterised by horseshoe-shaped trisilicate (Si (sub 3) O (sub 10) ) groups and zigzag chains of edge-sharing distorted MO (sub 6) octahedra (M=Gd, Er, Yb, Sc). Correlations between beta -, Si-Si-Si angle and unit-cell volume and REE (super 3+) ionic radii are discussed. The geometries of the Si (sub 3) O (sub 10) and T (sub 3) O (sub 10) groups (T=Ge, P, As, Al, Ga, V) in non-silicates are briefly reviewed, with special focus on narrow Si-Si-Si angles.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 22
Serial Issue: 2
Title: Synthesis and structural study of five new trisilicates, BaREE (sub 2) Si (sub 3) O (sub 10) (REE=Gd, Er, Yb, Sc) and SrY (sub 2) Si (sub 3) O (sub 10) , including a review on the geometry of the Si (sub 3) O (sub 10) unit
Affiliation: Universitaet Wien, Institut fuer Mineralogie und Kristallographie, Vienna, Austria
Pages: 245-258
Published: 201003
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 104
Accession Number: 2010-039536
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 8 tables
Secondary Affiliation: Naturhistorisches Museum, AUT, Austria
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201022
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