Journal
EUROPEAN JOURNAL OF MINERALOGY
Volume 22, Issue 2, Pages 245-258Publisher
COPERNICUS GESELLSCHAFT MBH
DOI: 10.1127/0935-1221/2010/0022-1969
Keywords
crystal structure; trisilicates; mixed octahedral-tetrahedral framework; flux-growth method; single-crystal X-ray diffraction; rare-earth elements
Categories
Ask authors/readers for more resources
Five new mixed-framework trisilicates were synthesised using a high-temperature flux growth technique. Colourless, glassy plates of SrY2Si3O10 crystallise in space group P (1) over tilde, with a = 6.757(1), b = 6.885(1), c = 9.273(2) angstrom, alpha = 72.42(3), beta = 86.37(3), gamma = 88.37(3)degrees, V = 410.38(12)angstrom(3), Z = 2. The main building units of the new structure type represented by SrY2Si3O10 are slightly curved Si3O10 trimers and Y2O11 dimers (composed of YO6 octahedra sharing an edge with YO7 polyhedra), which are further edge-connected to adjacent dimers to form twisted zigzag chains parallel to [010]. BaREE2Si3O10 (REE Gd, Er, Yb, Sc) form colourless small prisms, pseudohexagonal plates or isometric crystals, and crystallise in space group P2(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) angstrom, 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) angstrom(3), Z = 2. BaREE2Si3O10 (REE Gd, Er, Yb, Sc) are isotypic with BaY2Si3O10. Their topology is characterised by horseshoe-shaped trisilicate (Si3O10) groups and zigzag chains of edge-sharing distorted MO6 octahedra (M Gd, Er, Yb, Sc). Correlations between b-, Si-Si-Si angle and unit-cell volume and REE3+ ionic radii are discussed. The geometries of the Si3O10 and T3O10 groups (T Ge, P, As, Al, Ga, V) in non-silicates are briefly reviewed, with special focus on narrow Si-Si-Si angles.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available