ISSN:
1600-5740
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Dysprosium disilicate (Dy2Si2O7) is triclinic with a = 6.6158 (2), b = 6.6604 (2), c = 12.0551 (4) Å, α = 94.373 (2), β = 90.836 (2), γ = 91.512 (2)°, V = 529.4 (1) Å3, space group P\overline 1, Z = 4 and Dx = 6.156 g cm−3. The structure (single-crystal X-ray, R = 0.033, wR = 0.041) is built from a linear triple tetrahedral group [Si3O10] and isolated [SiO4] tetrahedron cross-linked by Dy3+ in one sixfold and three eightfold coordinated positions, and corresponds to the presently revised type B structure of Ho2Si2O7. The formation of the unusual linear triple tetrahedral group in the type B structure allows for a more continuous transition in the mean size of REE3+On (REE = rare earth element) polyhedra in REE disilicates through the 4f transition metal series. The crystal of Dy2Si2O7 investigated was complexly twinned such that the diffraction pattern was also consistent with a larger dimensionally monoclinic unit cell (a = 22.5354, b = 14.2102, c = 6.6158 Å, β = 91.788°), which resulted in an apparent superstructure of the type B structure in space group C1¯. Lattice coincidence with the type B unit cell appears to have been maintained during crystal synthesis and quenching by the complex sector-zoned growth twin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108768100008545
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