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Thortveitite-type Tm2Si2O7.

Kahlenberg V, Aichholzer P - Acta Crystallogr Sect E Struct Rep Online (2014)

Bottom Line: Each of the octa-hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001).The layers containing the octa-hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence.Linkage is provided by sharing common oxygen vertices.

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Affiliation: University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck, Austria.

ABSTRACT
Single crystals of dithulium disilicate, Tm2Si2O7, were obtained in flux synthesis experiments in the system SiO2-Tm2O3-LiF at ambient pressure. The compound belongs to the group of sorosilicates, i.e. it is based on [Si2O7]-units and crystallizes in the thortveitite (Sc2Si2O7) structure type. The Tm(3+) cation (site symmetry .2.) occupies a distorted octa-hedral site, with Tm-O bond lengths in the range 2.217 (4)-2.289 (4) Å. Each of the octa-hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001). The individual [SiO4] tetra-hedra are more regular, i.e. the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octa-hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.

No MeSH data available.


Representation of a single [Si2O7]-unit. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) x, y, -1 + z (ii) -x, y, -z (iii) -x, y, 1 - z (iv) x, -y, -1 + z].
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Fap1: Representation of a single [Si2O7]-unit. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) x, y, -1 + z (ii) -x, y, -z (iii) -x, y, 1 - z (iv) x, -y, -1 + z].


Thortveitite-type Tm2Si2O7.

Kahlenberg V, Aichholzer P - Acta Crystallogr Sect E Struct Rep Online (2014)

Representation of a single [Si2O7]-unit. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) x, y, -1 + z (ii) -x, y, -z (iii) -x, y, 1 - z (iv) x, -y, -1 + z].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120532&req=5

Fap1: Representation of a single [Si2O7]-unit. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) x, y, -1 + z (ii) -x, y, -z (iii) -x, y, 1 - z (iv) x, -y, -1 + z].
Bottom Line: Each of the octa-hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001).The layers containing the octa-hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence.Linkage is provided by sharing common oxygen vertices.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck, Austria.

ABSTRACT
Single crystals of dithulium disilicate, Tm2Si2O7, were obtained in flux synthesis experiments in the system SiO2-Tm2O3-LiF at ambient pressure. The compound belongs to the group of sorosilicates, i.e. it is based on [Si2O7]-units and crystallizes in the thortveitite (Sc2Si2O7) structure type. The Tm(3+) cation (site symmetry .2.) occupies a distorted octa-hedral site, with Tm-O bond lengths in the range 2.217 (4)-2.289 (4) Å. Each of the octa-hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001). The individual [SiO4] tetra-hedra are more regular, i.e. the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octa-hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.

No MeSH data available.